The International Journal of Oral & Maxillofacial Implants, 03/2017

Purpose: Avoiding excessive trauma-thermal or otherwise-during dental implant site preparation is considered critical to implant success; overheating is considered to be a major cause of bone necrosis. Studies evaluating thermal and mechanical effects of implant drill design are limited, and effects of flute design have not been accounted for. The purpose of this study was to compare heat generation and cutting efficiency associated with two-, three-, and four-fluted implant drills to investigate the optimal number of flutes. Materials and Methods: Two-, three-, and four-fluted dental implant drills with identical point, relief, and rake angles and otherwise standard dimensions were evaluated. Real-time temperature changes while drilling artificial bone were recorded using an infrared thermal imager. Cutting efficiency was assessed as the drilling time to a 15-mm depth under constant load using a specially designed recording system. Each drill variation was examined 20 times. A one-way analysis of variance was used for statistical analysis. Results: Mean temperature increases amounted to 8.3°C, 10.8°C, and 15.1°C for two-, three-, and four-fluted drills, respectively; temperatures significantly increased (P .001) with an increased number of flutes. Mean drilling time serving as a measure of cutting efficiency amounted to 2.6, 2.5, and 2.5 seconds for the two-, three-, and four-fluted drills, respectively. A trend of cutting efficiency increasing or decreasing according to the number of flutes was not observed. Differences in cutting efficiency among the three drill variations were statistically significant (P = .015). The cutting efficiency of the three-fluted drill was superior to that of the two-fluted drill (P = .016). Conclusion: Within the limitations of the study, a two-fluted drill would be preferred for osteotomy preparation due to its level of heat generation, whereas a three-fluted drill showed favorable cutting efficiency. Keywords: cutting efficiency, drill geometry, frictional heat, implant drill design

Purpose: To select an ideal interocclusal record material for cone beam computed tomography (CBCT)-guided implant surgery based on the material's radiodensity on the scan. Materials and Methods: Twelve commonly used interocclusal record materials were used for this investigation: two were waxes, one was polyether, and nine were polyvinyl-siloxane-type materials. A scan template was fabricated by duplicating existing dentures in Ortho-Jet acrylic resin mixed with 30% barium powder for the teeth and 10% barium powder for the denture base between the teeth and the tissue. An interocclusal record was fabricated with each material, and the same template was used to obtain a CBCT scan with an ICAT machine (Imaging Sciences International) at 0.3 voxel and 14-bit depth settings. Twelve CBCT scans were obtained and analyzed. The radiopacity of the barium teeth was used as a control and was compared with the opacity of the 12 materials using a paired t test. A post hoc analysis of variance (ANOVA) test was used to compare the densities of the various materials with each other. Results: There was a statistically significant difference between the radiopacity of barium teeth (gray value: 1,959.475) and that of Modelling Wax (gray value: 750; P = .0026), Aluwax (gray value: 795.22; P = .0022), Blu-Bite CT (gray value: 1,105; P = .005), Ramitec (gray value: 1,105.3; P = .08), Memosil 2 (gray value: 1,202; P = .01) followed by Reprosil (gray value: 1,407.73; P = .01). Compared with the barium teeth, there was no statistically significant difference between the densities of Futar D (gray value: 1,866.5; P = .51), Jet Bite (gray value: 1,660.04; P = .08), Lab-Putty (gray value: 1,402.14; P = .19), and Memoreg 2 (gray value: 1,754.72; P = .1). The highest radiodensity was seen with Blu-Mousse (gray value: 2,949; P = .007) and Take 1 (gray value: 2,229.85; P = .025), which were also significantly different from the density of the barium teeth but in the opposite direction, making them more opaque. Conclusion: Within the limitations of this in vitro study, the most radiolucent appearance of Modelling Wax, Aluwax, Memosil 2, Blu-Bite CT, and Ramitec made them the suitable materials of choice of those tested, as the interocclusal registration record during CBCT scanning allowed clear visualization of barium teeth. Keywords: barium guide, CBCT, guided surgeries, implant surgery, radiolucency, scan template

Purpose: In indexed literature, a systematic review of the efficacy of statins in enhancing osseointegration is lacking. The aim of this systematic review was to assess the efficacy of local and systemic statin delivery on the osseointegration of implants. Materials and Methods: To address the focused question, "Does local and systemic statin delivery affect osseointegration around implants?", indexed databases were searched from 1965 through November 2015 using various keywords. Letters to the Editor, case reports/case series, historic reviews, and commentaries were excluded. The pattern of this systematic review was customized to primarily summarize the pertinent data. Results: Nineteen studies were included. All studies were experimental and were performed in animal models. In seven studies, statins were delivered systemically via oral, intraperitoneal, intraosseous, subcutaneous, and percutaneous routes. Among the 12 studies, where statins were delivered locally, statin-coated implants were used in seven studies, whereas in the remaining studies, statins were delivered via topical application on the bone cavities. The follow-up duration ranged between 1 and 12 weeks. Results from 18 studies showed that statin administration enhanced new bone formation (NBF) around implants and/or bone-to-implant contact. One study showed that statin-coated implant surfaces impaired osseointegration. Seven studies reported that statin administration enhanced NBF around implants in osteoporotic rats. Conclusion: On experimental grounds, local and systemic statin delivery seems to enhance osseointegration; however, from a clinical perspective, further studies are needed to assess the role of statins in promoting osseointegration around dental implants. Keywords: dental implants, hydroxymethylglutaryl-CoA reductase inhibitors, osseointegration

Purpose: The aim of this study was to evaluate the effectiveness of fabrication methods (computer-aided design/ computer-aided manufacture [CAD/CAM], copy-milling, and conventional casting) in the fit accuracy of threeunit, screw-retained fixed dental prostheses. Materials and Methods: Sixteen three-unit implant-supported screw-retained frameworks were fabricated to fit an in vitro model. Eight frameworks were fabricated using the CAD/CAM system, four in zirconia and four in cobalt-chromium. Four zirconia frameworks were fabricated using the copy-milled system, and four were cast in cobalt-chromium using conventional casting with premachined abutments. The vertical and horizontal misfit at the implant-framework interface was measured using scanning electron microscopy at ×250. The results for vertical misfit were analyzed using Kruskal-Wallis and Mann-Whitney tests. The horizontal misfits were categorized as underextended, equally extended, or overextended. Statistical analysis established differences between groups according to the chi-square test (α = .05). Results: The mean vertical misfit was 5.9 ± 3.6 μm for CAD/CAM-fabricated zirconia, 1.2 ± 2.2 μm for CAD/CAM-fabricated cobaltchromium frameworks, 7.6 ± 9.2 μm for copy-milling-fabricated zirconia frameworks, and 11.8 (9.8) μm for conventionally fabricated frameworks. The Mann-Whitney test revealed significant differences between all but the zirconia-fabricated frameworks. A significant association was observed between the horizontal misfits and the fabrication method. The percentage of horizontal misfits that were underextended and overextended was higher in milled zirconia (83.3%), CAD/CAM cobalt-chromium (66.7%), cast cobalt-chromium (58.3%), and CAD/CAM zirconia (33.3%) frameworks. Conclusion: CAD/CAM-fabricated frameworks exhibit better vertical misfit and low variability compared with copy-milled and conventionally fabricated frameworks. The percentage of interfaces equally extended was higher when CAD/CAM and zirconia were used. Keywords: computer-aided design, computer-assisted manufacture, dental implants, implant-supported dental prosthesis, prosthetic fit, zirconia

Purpose: To evaluate whether there are differences in the accuracy of guided implant placement based on the surgeon's experience level. Materials and Methods: Fifteen surgeons, divided into three groups based on experience level (group I, expert; group II, intermediate; group III, novice), placed six implants in five identical mandibles (75 mandibles and 450 implants). A planning and stereolithographic guide was generated using cone beam computed tomography (CBCT) images and implant planning software (Nemoscan, Nemotec) and was used in all cases. After the implants were placed in each mandible, another scan was taken, and the three-dimensional (3D) images of each scan were blended with the images in the planning guide to evaluate any deviations. Any differences in platform and apex position and the angle of the implant were measured. The differences between each surgeon and each group were compared using multivariate analysis of variance (MANOVA). Results: There were significant differences in the implant angles among the three groups (P = .001). Group III (novices) presented the greatest angle deviation and showed more deviations than group I (experts) (P = .024) and group II (intermediate) (P = .001) did. There were no significant differences between groups I and II (P = .368). There were no significant differences among the groups in terms of platform (P = .135) and apex position (P = .092). Conclusion: Some degree of deviation can occur between the planned placement of the implant and its definitive placement, and this deviation may be influenced by the surgeon's experience. Expert surgeons show less angle deviation than novice surgeons. Although these differences (less than 0.5 degrees) are statistically significant, they may be considered clinically irrelevant. Keywords: computer-assisted, dental implants, guided surgery, implant placement accuracy, stereolithographic surgical guide

Purpose: To examine the disparity of single-crown implant failure with a similar loss of the splinted prosthesis in differing anatomical locations while controlling for other demographic and clinical variables that may confound the relationship between prosthesis types and implant loss. Materials and Methods: A multicenter retrospective cohort study was designed to include patients treated with dental implants from 2003 to 2014. The variables included age, sex, systemic disease, bone graft, implant placement date, position of dental implant, length of dental implant, diameter of dental implant, loading time, type of prosthesis, type of opposing occlusion, latest check date, and survival or loss of the dental implant. The demographic and clinical variables' influence on the survival of dental implants was estimated by the Kaplan-Meier method. The position and diameter were adjusted for the accurate estimation of the relationship between the prosthesis type and survival of the dental implant with the Cox proportional hazard method. Results: A total of 1,151 dental implants from 403 patients were ascertained. After adjusting for the confounding effect of position and diameter, single-crown prostheses were 38.1 (95% CI: 15.1-118) times more likely to be lost than the connected-type prostheses. For single-crown implants, the waiting time for osseointegration before loading was the highest for the maxillary molar position and the lowest for the mandibular molar position (P .0001), while the most frequent implant loss occurred in the maxillary anterior area, and the second frequent area was the maxillary molar position; the lowest occurrence of implant loss was for the mandibular molar position. This disparity was statistically significant (P = .0271). Conclusion: Despite the high survival rates of endosseous implants as a whole, since the variation of implant loss was observed among the different anatomical positions for single-crown implants, special attention has to be given to the maxillary anterior and maxillary molar positions. A longer healing time assuming compensation for disadvantageous bone quality was not directly effective in increasing implant longevity in the vulnerable positions. Keywords: bone quality, implant position, loading time, mortality gap, osseointegration, single-crown implant

Purpose: One-piece zirconia dental implants have been widely used in Europe for many years. This in vitro study was done to evaluate the effect of abutment preparation and fatigue (cyclic) loading in a moist environment on the fracture resistance of the one-piece zirconia dental implant. Materials and Methods: Twenty-four Cera Root zirconium oxide dental implants, divided into three groups of eight, were used in this study: group 1 (control group): implants with no preparation, tested in a dry environment; group 2: implants with no preparation, tested in a moist environment (simulating clinical conditions); and group 3: implants after abutment preparation tested in a moist environment. All implants received IPS e.max porcelain crowns. All samples were subjected to nearly 1 million cycles of sinusoidal fatigue loading (-10 N to -200 N) in a universal testing machine. The postfatigue samples were loaded to fracture. Significant differences (α = .05) in mean fracture loads were statistically analyzed. Results: There was no catastrophic failure of any of the implants during the fatigue tests. The mean (SD) of the fracture loads in postfatigue load-to-failure tests were: group 1: 1,202.9 (62.6); group 2: 1,164.6 (73.8); and group 3: 953.5 (103). Analysis of variance (ANOVA) and post hoc Tukey-Kramer contrast revealed a statistically significant difference (P .05) between the mean fracture load of group 3 and those of groups 1 and 2, but no significant difference (P > .05) between groups 1 and 2. Conclusion: While there was a statistically significant adverse effect of abutment preparation and fatigue loading in a moist environment on the postfatigue implant failure load, the load-tofracture mean of surface-prepared implants after fatigue tests was nevertheless significantly higher than the mean fracture load of the crowns (P .05) as well as the minimum load-bearing requirement (300 N) for anterior restorations. Abutment preparation in a one-piece zirconia implant is therefore considered clinically safe and acceptable. Keywords: fatigue cyclic loading, fracture load, moist environment, one-piece zirconia dental implant

Purpose: The placement of immediate implants has become a routine treatment modality for the replacement of missing teeth. The aim of the present study was to evaluate dimensional changes of hard tissues following tooth extraction, implant bed preparation, and the subsequent integration of titanium implants placed immediately or following an 8-week healing period. Materials and Methods: All mandibular premolars were extracted and used as experimental sites in five beagle dogs. The left quadrant was used to compare the healing of alveolar bone following regular tooth extraction or surgical implant bed preparation. The right quadrant was used to compare immediate with delayed implant placement (3.3 mm, Bone Level SLActive, Roxolid, Straumann) after an 8-week healing period. All samples were assessed histologically for new bone area/total area (BATA), bone-to-implant contact (BIC), and bone height changes from the buccal and lingual midlines. Results: Implant bed preparation led to significantly lower BATA values and bone height loss compared with regular extraction sockets (-2.46 mm vs -1.44 mm, respectively; P = .0007). Placement of immediate implants demonstrated buccal and lingual bone height loss of 1.51 mm and 0.91 mm, respectively, whereas only 0.12 mm and 0.12 mm of bone height loss was observed during delayed implant placement. A significantly higher BIC was observed for implants placed immediately compared with delayed placement (52% vs 35%, P .05). Conclusion: Implant bed preparation further increased dimensional changes when compared with routine extraction sockets. Although immediate implant placement produced better BIC than did delayed placement, a significantly higher bone height loss at both the buccal and lingual midlines was reported. Further investigation is underway to minimize dimensional changes following immediate implant placement. Keywords: bone-to-implant contact, dental implants, extraction sockets, immediate implants, osseointegration

Purpose: There is interest in establishing hypoglycemiant agents able to contain/revert the impact of diabetes mellitus on osseointegration. The purpose of this study was to assess the possible effect of metformin in reversing the negative effects of hyperglycemia on the healing of bone surrounding implants inserted in rats. Materials and Methods: Rats (10 per group) were assigned to one of the following groups: DM group: type 2 diabetic rats deprived of metformin (M) treatment; MDM group: type 2 diabetic rats under M treatment (40 mg/kg/day, starting on the 15th day after implant placement); control group: nondiabetic rats without M treatment. At 30 days after streptozotocin injection, titanium implants were placed in tibiae. Animals were euthanized 30 days after implant surgery. Bone-to-implant contact (BIC), bone area (BA), and the number of receptor activator of nuclear factor κB ligand (RANKL)- and osteoprotegerin (OPG)-stained cells were assessed in cortical and medullary areas. Results: The percentages of BIC and BA in the cortical bone were reduced in the DM and MDM groups compared with the control group (P .05). The percentage of BA in the medullary region was reduced in the DM group compared with the control group (P .05). The MDM group showed the greatest number of OPG-stained cells, while the DM group presented the greatest ratio of RANKL/OPG in the medullary area (P .05). Conclusion: Metformin did not modulate the damaging effect of hyperglycemia on bone healing around implants at histometric levels, but increased the expression of OPG and decreased the RANKL/OPG ratio in the medullary area, yielding some molecular benefits in the osseointegration of implants under the hyperglycemic state. Keywords: dental implants, diabetes mellitus, metformin, osteoprotegerin, RANK ligand

Purpose: Citation analysis is the field of bibliometrics that uses citation data to evaluate the scientific recognition and the influential performance of a research article in the scientific community. The aim of this study was to conduct a bibliometric analysis of the top-cited articles pertaining to implant dentistry, to analyze the main characteristics, and to display the most interesting topics and evolutionary trends. Materials and Methods: The 100 top-cited articles published in "Dentistry, Oral Surgery, and Medicine" journals were identified using the Science Citation Index Database. The articles were further reviewed, and basic information was collected, including the number of citations, journals, authors, publication year, study design, level of evidence, and field of study. Results: The highly cited articles in implant dentistry were cited between 199 and 2,229 times. The majority of them were published in four major journals: Clinical Oral Implants Research, International Journal of Oral & Maxillofacial Implants, Journal of Clinical Periodontology, and Journal of Periodontology. The publication year ranged from 1981 to 2009, with 45% published in a nine-year period (2001 to 2009). Publications from the United States (29%) were the most heavily cited, followed by those from Sweden (23%) and Switzerland (17%). The University of Göteborg from Sweden produced the highest number of publications (n = 19), followed by the University of Bern in Switzerland (n = 13). There was a predominance of clinical papers (n = 42), followed by reviews (n = 25), basic science research (n = 21), and proceedings papers (n = 12). Peri-implant tissue healing and health (24%), implant success/failures (19.2%), and biomechanical topics (16.8%) were the most common fields of study. Conclusion: Citation analysis in the field of implant dentistry reveals interesting information about the topics and trends negotiated by researchers and elucidates which characteristics are required for a paper to attain a "classic" status. Clinical science articles published in highimpact specialized journals are most likely to be cited in the field of implant dentistry. Keywords: bibliometrics, citation analysis, implant dentistry

Purpose: This study aimed to evaluate how as-built electron beam melting (EBM) surface properties affect the onset of blood coagulation. The properties of EBM-manufactured implant surfaces for placement have, until now, remained largely unexplored in literature. Implants with conventional designs and custom-made implants have been manufactured using EBM technology and later placed into the human body. Many of the conventional implants used today, such as dental implants, display modified surfaces to optimize bone ingrowth, whereas custom-made implants, by and large, have machined surfaces. However, titanium in itself demonstrates good material properties for the purpose of bone ingrowth. Materials and Methods: Specimens manufactured using EBM were selected according to their surface roughness and process parameters. EBM-produced specimens, conventional machined titanium surfaces, as well as PVC surfaces for control were evaluated using the slide chamber model. Results: A significant increase in activation was found, in all factors evaluated, between the machined samples and EBM-manufactured samples. The results show that EBM-manufactured implants with as-built surfaces augment the thrombogenic properties. Conclusion: EBM that uses Ti6Al4V powder appears to be a good manufacturing solution for load-bearing implants with bone anchorage. The as-built surfaces can be used "as is" for direct bone contact, although any surface treatment available for conventional implants can be performed on EBM-manufactured implants with a conventional design. Keywords: bone ingrowth, coagulation, customization, electron beam melting, surface roughness

Purpose: Preclinical and clinical studies have shown that marginal bone loss can be secondary to repeated disconnection and reconnection of abutments that affect the peri-implant mucosal seal. The aim of this systematic review and meta-analysis was to evaluate the impact of abutment disconnections/reconnections on peri-implant marginal bone level changes. Materials and Methods: To address this question, two reviewers independently performed an electronic search of three major databases up to October 2015 complemented by manual searches. Eligible articles were selected on the basis of prespecified inclusion and exclusion criteria after a two-phase search strategy and assessed for risk of bias. A random-effects meta-analysis was performed for marginal bone loss. Results: The authors initially identified 392 titles and abstracts. After evaluation, seven controlled clinical studies were included. Qualitative assessment of the articles revealed a trend toward protective marginal bone level preservation for implants with final abutment placement (FAP) at the time of implant placement compared with implants for which there were multiple abutment placements (MAP). The FAP group exhibited a marginal bone level change ranging from 0.08 to 0.34 mm, whereas the MAP group exhibited a marginal bone level change ranging from 0.09 to 0.55 mm. Meta-analysis of the seven studies reporting on 396 implants showed significantly greater bone loss in cases of multiple abutment disconnections/reconnections. The weighted mean difference in marginal bone loss was 0.19 mm (95% confidence interval, 0.06-0.32 mm), favoring bone preservation in the FAP group. Conclusion: Within the limitations of this meta-analysis, abutment disconnection and reconnection significantly affected peri-implant marginal bone levels. These findings pave the way for revisiting current restorative protocols at the restorative treatment planning stage to prevent incipient marginal bone loss. Keywords: bone loss, dental abutments, dental implants, follow-up studies, osseointegration, titanium

Purpose: The present study hypothesized that different bone healing patterns through initial stages of osseointegration would be observed when three distinct commercially available implant systems (Nobel Groovy, Implacil, and Zimmer TSV) were used, leading to significant variations in histometric levels of total bone and new bone formation during the osseointegration process. Materials and Methods: A total of 48 implants were placed bilaterally on the tibias of eight beagle dogs and allowed to heal for 2 and 6 weeks. Following euthanasia, nondecalcified specimens were processed for morphologic and histometric evaluation. Bone-to-implant contact (BIC) and new bone area fraction occupancy (BAFO) analyses for native and new bone were performed along the whole perimeter of each implant and separately for the cortical and trabecular bone regions. Results: Morphologic evaluation of cortical bone presented different healing patterns and osseointegration levels for different implant systems as time elapsed in vivo. Interfacial remodeling was the chief healing pattern in Zimmer implants, while a combination of interfacial remodeling and healing chambers was observed in Nobel and Implacil implants. When trabecular bone was evaluated, similar bone healing patterns were observed between systems despite different levels of osseointegration observed as a function of implantation time, implant system, and native and/or new bone BIC and BAFO. Conclusion: Different implant systems led to different healing patterns during early stages of osseointegration. Such variation in pattern was more noticeable in the cortical regions compared to the trabecular regions. The variation in bone healing pattern did significantly influence overall indicators of native and new BIC and BAFO during the osseointegration process. The postulated hypothesis was accepted. Keywords: bone marrow, dental implants, design, histology, osseointegration

Purpose: A diagnostic wax try-in has been recommended to correctly design the future prosthesis for edentulous maxillae and to predict its effect on the supporting oral tissues. The objectives of this study were to analyze (1) the reliability of this diagnostic tool in planning fixed implant-supported prostheses and (2) the amount of prosthetic compensation required. Materials and Methods: Nine female patients participated in this prospective study (mean age, 53.6 years). After anamnesis, clinical examination, and preoperative analysis, the patients underwent preoperative prosthetic preparation, and the wax try-in was fabricated. To evaluate the efficiency of the diagnostic wax try-in, three profile cephalograms were taken of each patient: (1) with the initial conventional prosthesis, (2) with the wax try-in, and (3) with the implant-supported prosthesis. Two analyses were carried out for the assessment of lip support: the nasolabial angle and Steiner's S-line. To analyze the amount of prosthetic compensation, two measurements-vertical and horizontal distances- were obtained for each wax try-in and final prosthesis. Results: For the Steiner's S-line, the results of the statistical tests indicated no significant difference between the initial and final prosthesis for the upper (P = .237) and lower lips (P = .237), and between the wax try-in and final prosthesis for the upper (P = .463) and lower lips (P = .463). Regarding the nasolabial angle, the results of the statistical tests indicated no significant difference between the initial and final prosthesis (P = .594), and between the wax try-in and final prosthesis (P = .800). Regarding prosthetic compensation, the results of the statistical test indicated no significant difference between the vertical (P = .753) and horizontal evaluations (P = .855) carried out for the wax try-in and those for the final prosthesis. Conclusion: On the basis of the data collected, it was concluded that the methods of replacing muco-supported prostheses with implant-supported fixed prostheses were efficient at maintaining the original lip design. The wax try-in was capable of predicting the future lip design and the prosthetic compensation of the final prosthesis. More studies are required to consolidate these data. Keywords: dental implants, fixed dental prosthesis, oral rehabilitation, prosthetic planning, total prosthesis

Purpose: To investigate the presence of metallic particles in the peri-implant mucosa around titanium dental implants after 5 years of loading using single-implant crowns with respect to clinical signs of peri-implant inflammation. Materials and Methods: Sixteen participants from an ongoing, prospective, single-arm clinical trial who had received titanium dental implants restored with single maxillary crowns veneered to zirconia abutments were available for the study. Exfoliative cytology samples were obtained from the periimplant tissues and contralateral tooth sites using microbrushes and were evaluated by means of light microscopy (LM), scanning electron microscopy, and energy-dispersive spectroscopy (EDS). Trace elemental analysis was also carried out on the microbrushes using inductively coupled plasma mass spectrometry. Peri-implant and periodontal parameters (plaque, bleeding, attachment level, radiographic bone levels) were recorded. Results: Titanium particles were found in both the single-implant crown and contralateral natural tooth sites. LM and EDS analyses showed significantly higher numbers of Ti particles at the implant-abutment interfaces (mean = 14.168; SD = 2.36) and in the internal aspects of peri-implant mucosa in contact with the prostheses (mean = 4.438; SD = 2.22) when compared with other test and control areas. Mean probing depths were ≤ 3 mm, and no differences were found in plaque or bleeding on probing between implant and tooth sites. Median bone levels were within the normal range for both implant (mesial: 0.5 mm; distal: 0.8 mm) and tooth (mesial: 1.5 mm; distal: 1.8 mm) sites. Conclusion: Loading of single-implant zirconia crowns can cause the release of Ti particles because of functional wear at the implant-abutment level. The presence of these metal particles in the peri-implant area did not appear to affect peri-implant health in this patient group. Keywords: dental implants, microscopy, polarized light, scanning electron microscopy, single-arm trial, single tooth, spectroscopy, titanium, wear, zirconia

Purpose: Many histologic and histomorphometric studies as well as systematic reviews have shown the clinical success of the use of anorganic bovine bone (ABB, Bio-Oss) in maxillary sinus floor augmentation (MSFA). The molecular processes involved in bone healing are, however, still unknown. The aims of this study were to explore gene expression associated with bone remodeling and inflammation in MSFA sites. Materials and Methods: The mRNA expression levels of runt related transcription factor 2 (RUNX2), receptor activator of NF-kB ligand (RANKL), osteoprotegerin (OPG), matrix metallopeptidase 9 (MMP-9), tartrate-resistance acid phosphatase (TRAP), and interleukin-1beta (IL-1β), as well as the ratio of RANKL/ OPG were compared between alveolar bone of a group after MSFA with ABB and a maxillary posterior edentulous bone group. Twenty-one bone samples were collected at the time of implant placement after 6 months of MSFA or tooth extraction. Fourteen bone samples from the MSFA group and from the maxillary posterior edentulous bone without MSFA group were taken to analyze gene expression by real-time reverse transcription polymerase chain reaction (RT-PCR). Seven bone samples from the MSFA group were used for histologic analysis. Results: Real time RT-PCR revealed no statistically significant difference in gene expression level of RUNX2, RANKL, OPG, MMP-9, TRAP, and IL-1β, or in the ratio of RANKL/OPG. Histology showed bone-lining cells at the edge and osteocyte inside newly formed bone. Residual grafted particles were in close contact with new bone. Conclusion: After a healing period of 6 months, ABB particles did not have an effect on the expression of genes associated with bone remodeling and inflammation. In addition, histologic evidence supports that ABB particles are replaced by new bone formation and do not affect bone healing. Keywords: gene expression, histology, histomorphometry, maxillary sinus floor augmentation, real-time RT-PCR, xenograft

Purpose: To investigate the difference in accuracy between freehand and guided single-implant placement in situations with one or more missing teeth as performed by experienced surgeons. Materials and Methods: A total of 80 implants were placed by 10 experienced clinicians in the anterior site of maxillary models, made of polyamide by selective laser sintering and mounted in a dummy head. Each clinician performed the same four single-implant cases via freehand surgery and then with a three-dimensional fabricated SIMPLANT Guide. Two of the four cases had a single anterior tooth missing and the other two models represented a partially edentulous situation with several missing anterior teeth. For all 80 implants the average vertical, lateral, and angular deviations between the virtually planned and the achieved implant positions were measured based on a cone beam computed tomography (CBCT) scan. Results: Regarding the whole sample, angular deviation was 7.63 degrees for the freehand method and 2.19 degrees for guided surgery. The mean difference in angular deviation differed significantly between groups and was more than three times larger for the freehand method. Lateral deviation at the coronal level of the implants was 0.42 mm and 1.27 mm for the guided and freehand methods, respectively, and at the apical level was 0.52 mm and 1.28 mm for the guided and freehand methods, respectively; the deviation at the coronal and apical levels was significantly smaller for guided surgery than for the freehand method (P = .001). Differences in the depth deviation at the apical and coronal levels were smaller (guided vs freehand surgery at the coronal level: 0.54 mm vs 0.78 mm; apical level: 0.54 mm vs 0.73 mm) but also of statistical significance (P = .05). Differences in angular, global, and lateral deviations between the clinical situations (single vs multiple missing teeth) were also significantly smaller for guided surgery, whereas the deviations in depth did not reveal any statistically significant difference between both methods for the single-spaced units. Conclusion: In cases of one or more missing teeth in the anterior maxilla, guided surgery gives even experienced surgeons significantly higher predictability and accuracy than freehand surgery in transferring the virtual implant position to a model situation. Keywords: 3D-implant planning, freehand surgery, guided surgery, implant deviation

Purpose: To evaluate the esthetic result of immediately placed implants with immediate provisional restorations in the anterior maxilla using the pink esthetic score (PES) and white esthetic score (WES). Materials and Methods: The records of patients were evaluated retrospectively. The evaluation was carried out by two examiners using 12 evaluation criteria. Results: The average PES value from the evaluation of 53 images obtained from the 53 selected patients (22 men and 31 women) was 8.63 ± 2.4 (range, 1-14), whereas the average WES value was 6.92 ± 1.67 (range, 2-10). The mesial papilla had the highest average PES (1.39 ± 0.4) and the distal papilla had the lowest PES (0.87 ± 0.54). Texture had the highest average WES (1.54 ± 0.34) and tooth shape had the lowest average WES (1.25 ± 0.43). Conclusion: Treatment with immediate implants providing immediate provisional restoration in the anterior maxilla yields good clinical esthetic outcomes, as assessed by PES/WES values. The PES and WES values showed strong intraexaminer agreement, but weak interexaminer agreement. Keywords: esthetic zone, immediate implants, immediate restoration, pink esthetic score, white esthetic score

Purpose: This study was designed to evaluate long-term performance of zygomatic implants using an alternative apical fixation point to establish the posterior restorative foundation for fixed full-arch restoration. Materials and Methods: A retrospective study of all consecutively treated patients with advanced maxillary resorption who were treated with zygomatic implants to support fixed prostheses from August 14, 2001 through November 24, 2009 was conducted; the final follow-up was August 31, 2015. All zygomatic implants were placed using the malar prominence of the maxillary bone for apical fixation. Initial study casts were analyzed to compute the anterior/posterior implant distribution, distance between bilateral zygomatic implants, and variation from ideal zygomatic implant positioning relative to the soft tissue crest. Soft tissue, implant, and restorative complications also were recorded. Results: Fifty-eight consecutively treated patients with advanced maxillary resorption were included in the study- 18 men and 40 women, with a mean ± SD age of 65.3 ± 8.0 years and range of 49 to 85 years. Forty-nine patients received bilateral zygomatic implants placed apically into the malar process of the maxillary bone, and nine patients received similarly placed unilateral zygomatic implants with 107 zygomatic implants reported. All patients had supplemental anterior implants and were restored with a one-piece splint framework and fully implant-supported restoration. Follow-up of 5 to 13 years was conducted, with a mean follow-up time of 8.4 years per zygomatic implant. No losses of zygomatic implants occurred. No major surgical or restorative complications were observed. Conclusion: Utilizing the malar prominence of the maxilla for apical fixation of zygomatic implants predictably allows prosthetic placement of the implant platform in a favorable first molar position, eliminating prosthetic compromise. Keywords: implant, malar, maxilla, sinus, zygoma, zygomatic

Purpose: Application of endosseous implants in prosthetic orbital reconstruction seems to be very successful, but few reports have evaluated cumulative survival rates of orbital implants over a long period. The aim of this study was to analyze long-term survival rates and potential influencing factors of orbital implants. Materials and Methods: A retrospective evaluation of patients treated with extraoral screw implants for retaining orbital prostheses from 1991 to 2014 was performed. Patient records were assessed for implant survival, demographic data, defect etiology, irradiation status, location of implant placement, implant systems, length, and retention type. Data were analyzed using the Kaplan-Meier method and log-rank test to compare survival curves. Results: A total of 282 orbital implants placed in 78 patients were evaluated during an observation period ranging from 2 to 268 months (mean: 94.97 months). The cumulative implant survival rate was 91.3% at 2 years, 80.5% at 5 years, 68.7% at 10 years, and 62.2% after 15 years. The survival rate was significantly higher in females (75.3%) vs males (47.3%), in supraorbital vs infraorbital implants (67.4% vs 51.5%), and in Brånemark implants (70.2%) vs Straumann implants (54.5%). Conclusion: The presented data suggest that the long-term predictability of orbital implants revealed good to acceptable results. Factors such as female gender, localization in the supraorbital rim, a machined surface of the implant system, length, and magnetic retention seem to affect the implant survival rate positively, whereas irradiation status does not show any influence. These factors should be considered in planning future patient rehabilitation. Keywords: exenteration, facial prosthesis, orbital implant, reconstruction

Purpose: The aim of this study was to review the indications for implant placement, early outcomes, and associated risk factors. Materials and Methods: A retrospective cohort study design was used. The study was composed of a group of 509 consecutive patients, which represented the total number of patients treated from 2012 to 2014 in the Department of Oral and Maxillofacial Surgery, University Hospitals Leuven, Belgium. The authors analyzed the indications for implant placement and the potential risk factors for early implant failure. Results: A total of 509 patients received 1,139 dental implants. The group consisted of 240 men and 269 women, with a median age of 58 years. The most frequent indication for implant placement was restoration of a partially edentulous arch (80.1%, n = 408). For 152 implants (13.3%), additional bone-augmentation or sinus elevation procedures were required. Early failures were recorded for 52 (4.6%) implants in 33 patients (6.5%). Smoking, male gender, total edentulism, implant diameter, and bone augmentation surgery were found to be associated with early implant failure. Conclusion: Patients referred for implant placement were more likely to be partially edentulous and older than 50 years. Singletooth replacement in the posterior mandible was the most frequent indication (24.4%) for treatment. This study found an early success rate of 95.4% and identified risk factors for early failures. Keywords: dental implants, early failure, implant success, implant survival, indication

Purpose: The immediate placement of single postextractive implants is increasing in the everyday clinical practice. Due to insufficient bone tissue volume, proper primary stability, essential for subsequent osseointegration, is sometimes not reached. The aim of this work was to compare two different approaches: implant bed preparation before and after root extraction. Materials and Methods: Twenty-two patients of both sexes were selected who needed an implant-prosthetic rehabilitation of the fractured first mandibular molar or presented an untreatable endodontic pathology. The sites were randomly assigned to the test group (treated with implant bed preparation before molar extractions) or control group (treated with implant bed preparation after molar extractions) by a computer-generated table. All implants were placed by the same operator, who was experienced in both traditional and ultrasonic techniques. The implant stability quotient (ISQ) and the position of the implant were evaluated. Statistical analysis was carried out. Results: In the control group, three implants were placed in the central portion of the bone septum, while eight implants were placed with a tilted axis in relation to the septum; in the test group, all implants were placed in ideal positions within the root extraction sockets. The different position of the implants between the two procedures was statistically significant. Conclusion: This work presented an innovative approach for implant placement at the time of mandibular molar extraction. Preparing the implant bed with an ultrasonic device before root extraction is a simple technique and also allows greater stability to be reached in a selective case. Keywords: extraction, implant site preparation before root extraction, molars, ultrasonic surgery

Purpose: The aim of this randomized clinical trial was to radiographically compare peri-implant marginal bone level changes between immediately loaded implants without the removal of an abutment placed at the time of surgery (IL), delayed loaded nonsubmerged implants (NS), and delayed loaded submerged implants (SI). Materials and Methods: Patients' edentulous sites were randomly allocated to the three groups of implants so that each patient received one implant of each group. Digital periapical radiographs were obtained at baseline as well as three (T1), six (T2), and nine (T3) months after implant insertion. The mesial and distal bone crest levels adjacent to each implant were measured, and the mean values were calculated for each implant at each period. The data were statistically analyzed by repeated measures analysis of variance (ANOVA) and the Tukey test (P .05). Results: The patient sample comprised 15 subjects (13 women and 2 men; mean age: 47.7 years) with partially edentulous sites in the mandibular posterior area. Forty-five implants were inserted (15 IL implants, 15 NS implants, and 15 SI implants). There was no statistically significant difference between the three groups with regard to changes in the marginal bone level during the follow-up period. The study achieved a 93.3% cumulative survival rate for both delayed loaded groups (NS and IS) and a 100% survival rate for the IL group. Conclusion: In the 9-month period following the implants, no statistically significant differences were found between immediately and delayed loaded implants or between submerged and nonsubmerged implants in bone level changes in patients with partial posterior mandibular edentulism. Keywords: bone regeneration, dental implant, marginal bone level, osseointegration

Purpose: To assess patient satisfaction and patient-related outcomes across the domains of appearance, cleansibility, and costs; the perceived value and worth when single implant crowns (SICs) had been in situ up to 14 years; whether satisfaction differed between patients; and whether certain characteristics might affect the questionnaire response rate. Materials and Methods: Patients treated at a private prosthodontic practice between 2001 and 2014 (n = 207) who received a SIC (n = 256) were prospectively included. A previously validated patient satisfaction questionnaire (PSQ) exploring patient-centered outcomes was mailed to participants. Demographic (sex, age) and treatment data (number of SICs, time in situ, failure experience, complication experience) were collected. Visual analog scale (VAS) responses were converted to percentages. Differences between respondents and nonrespondents, differences in satisfaction between prosthesis placement and survey date, and differences with respect to demographic and treatment data were assessed. Averages were medians bounded by interquartile ranges. Statistical significance was set at P = .05. Results: Respondents (n = 128, 61.8%) and nonrespondents (n = 79, 38.2%) had similar demographic and treatment characteristics. Prostheses had been in situ for up to 14 years (median, 5 years; interquartile range [IQR], 24 to 96 months). Participants reported that treatment met their expectations (median, 93%; IQR, 85% to 100%); they reported high satisfaction with tooth color, tooth contour, peri-implant mucosa, appearance overall, and ease of cleaning (medians ranging from 90.5% to 95%, IQR ranging from 80% to 100%) and medium satisfaction with costs when prostheses were placed (median, 50%; IQR, 29% to 80%). Satisfaction with tooth contour, peri-implant tissues, overall appearance, and costs significantly improved over time (96%, 92.5%, 91.7%, and 75%, respectively; P .001 to P = .049). Levels of satisfaction did not differ by sex, number of implants, survival, complications, number of complications, and time in situ. Younger patients were less satisfied with the overall appearance and costs than older patients (P = .004, P = .007, respectively). All patients would choose to undergo treatment again and would recommend it to a friend. Conclusion: Patients with SICs that were in situ up to 14 years who responded to the validated PSQ were highly satisfied with the appearance and cleansibility, noted improvements in peri-implant tissue contours, and found the treatment to be valuable and worthwhile. They reported that upfront costs were high, but this concern decreased when the SICs had been in the mouth for a period of time. Keywords: fixed prosthodontics, implant-supported single crowns, patient satisfaction, patient-centered outcomes research

Purpose: To correlate soft tissue thickness and peri-implant bone remodeling of platform-switching implants. Materials and Methods: This comparative prospective trial evaluated, for up to 3 years after implant loading, the influence of soft tissue thickness on changes in peri-implant marginal hard tissue levels. Any patient who was partially edentate in the mandible and required at least two adjacent implant-supported restorations was recruited at the University of Valencia in Spain. A 3-mm tissue punch biopsy, which corresponded to a diameter slightly smaller than the coronal diameter of the implants, was performed using a circular mucotome. Afterward, implants with a length of 10 to 13 mm and a diameter of 3.8 mm were inserted. Outcome measures were implant and prosthesis survival rates, marginal hard tissue changes, any complications, and results of morphologic and histomorphometric analyses. Correlation between mucosa width components (epithelium, connective tissue, and epithelium and connective tissue) and radiographic bone loss at 1 and 3 years after loading was performed at the patient level. Statistical significance was set at P ≤ .05. Results: A total of 26 samples in 26 patients with 68 implants were analyzed. The specimens were divided into two groups: group 1 (16 patients, 40 implants), with thin mucosa (≤ 2 mm), and group 2 (10 patients, 28 implants), with thick mucosa (> 2 mm). Two dropouts (two specimens) were recorded at the 3-year follow-up. None of the implants or definitive prostheses failed during the healing period, resulting in an overall implant and prosthesis cumulative survival rate of 100%. No major biologic or mechanical complications were recorded. The mean (standard deviation, SD) epithelium thickness was 430.33 (250.21) μm; the mean (SD) connective tissue thickness was 1,324.31 (653.46) μm, and the mean (SD) mucosa thickness was 1,751.29 (759.53) μm. Comparisons of radiographic bone loss between group 1 and group 2 failed to show any statistically significant differences at the 1-year (P = .290) or 3-year (P = .090) follow-up examinations. Conclusion: The initial mucosa thickness surrounding a bone-level platform-switching implant seems not to influence the pattern of physiologic marginal bone loss. Keywords: dental implants, marginal bone loss, mucosa thickness, platform switching

Purpose: To analyze the occurrence of intraoperative complications during sinus floor elevation with a lateral approach and their correlations with the technique adopted by surgeons. Materials and Methods: Electronic and manual searches resulted in 4,417 records on sinus floor elevation. Twenty-one randomized clinical trials (RCTs) and 11 prospective controlled clinical trials (CCTs) reporting occurrence of intraoperative complications were included. Risk of bias was assessed according to the Cochrane tool and a modified Downs and Black quality analysis for RCTs and CCTs, respectively. Results: Sinus membrane perforation and hemorrhagic events following vascular lesions were the only intraoperative complications reported by the selected studies with overall occurrences of 15.7% and 0.4%, respectively. Three different surgical devices (rotary instruments, piezoelectric osteotomes, and manual bone scrapers) were used to perform the lateral antrostomy. Ultrasonic devices and bone scrapers showed a lower incidence (10.9% and 6.0%, respectively) of membrane perforation compared with that of rotary instruments (20.1%). Among the different ultrasonic procedures, erosion of the lateral antral wall showed the lowest membrane perforations (4.7% incidence). Hemorrhagic complications seemed to be extremely infrequent with any surgical technique. Conclusion: Sinus membrane perforation was the most frequently described intraoperative complication during sinus floor elevation with a lateral approach. Thinning the lateral wall of the sinus before performing the antrostomy (either with ultrasonic devices or manual bone scrapers) seemed to be an important factor in preventing membrane perforation during sinus surgery. Further high-quality RCTs specifically investigating intraoperative complication occurrence are needed. Keywords: hemorrhagic complications, intraoperative complications, membrane perforation, sinus floor elevation

Purpose: To compare the effectiveness of different methods of fractured screw fragment retrieval from dental implants, comparing a conventional method (use of an exploration probe and ultrasonic tips) with two mechanical retrieval kits. Materials and Methods: One hundred thirty-five screws in implant internal connections were fractured to test fragment retrieval comparing three methods: conventional method with the use of an explorer probe and ultrasonic tips (group CE), extraction with a mechanical kit with a guide cylinder (group MK1), and extraction with a mechanical kit without a guide cylinder (group MK2). Extraction success and retrieval times for each method, as well as success and retrieval times in relation to fracture depth-coronal, middle, or apical-were analyzed by means of chi-square, Fisher exact, Kruskal-Wallis, and Mann-Whitney tests (P .05). The integrity of implant internal threads was also analyzed. Results: The extraction success rates for groups MK2, CE, and MK1 were 93.3%, 73.3%, and 20%, respectively. The mean ± SD extraction times were 2 minutes, 56 seconds ± 2 minutes, 9 seconds; 3 minutes, 15 seconds ± 1 minute, 48 seconds; and 13 minutes, 34 seconds ± 7 minutes, 25 seconds for groups MK2, CE, and MK1, respectively. Statistically significant differences were found in the number of fractured screws extracted and in the retrieval time. No significant differences were found for retrieval time or extraction success in relation to the depth of the fracture. Conclusion: The mechanical kit without the guide cylinder achieved the best results with respect to the number of screw fragments retrieved, retrieval time, and preservation of implant internal threads. Keywords: fragment screw, implant, mechanical kits, prosthetic

Purpose: The aim of the present study was to systematically evaluate the marginal bone loss (MBL), success, and survival of zirconia (Zi) implants and compare them with the widely studied titanium (Ti) implants. Materials and Methods: An electronic and manual literature search of several databases was performed by two independent reviewers for articles up to July 2015 that reported the use of Zi implants and survival, success, and MBL with at least 12 months' follow-up. In addition, random effects meta-analyses of selected studies were applied to analyze the weighted mean difference of survival, success, and MBL between groups. Meta-regression analysis was conducted to investigate any potential influence of confounding factors. Results: Twenty-one articles were included, analyzing a total of 1,948 Zi implants with a survival rate of 91.5% and a success rate of 91.6% for 1,250 Zi implants. In addition, three studies were included in the quantitative synthesis and were meta-analyzed for the comparison of survival between Zi and Ti implants, with Zi implants having an 89% greater risk of failure compared with Ti implants (OR = 1.89). There were no statistically significant differences (P = .968) in the success of Zi and Ti implants (odds ratio [OR] = 1.02; 95% confidence interval [CI], 0.47-2.20). MBL (± SD) for Zi implants was 0.89 ± 0.18 mm, which was greater than the MBL for Ti implants (mean difference = 0.14 mm). Also, survival of Zi implants (91.5%) was significantly lower than that of Ti implants (OR = 1.89). Metaregression analysis revealed a similar survival rate for one-piece versus two-piece implants. Similarly, no significant differences were found between immediate and delayed loading. Conclusions: The survival rate of Zi implants was significantly lower than that for the commonly used Ti implants. However, for certain clinical conditions, such as a thin tissue biotype or in the highly esthetic anterior area, Zi implants may offer some benefit when compared with Ti implants. Keywords: alveolar bone loss, dental implants, dental prosthesis, edentulous, jaw, zirconium

Purpose: This study aimed to evaluate the effect of buccal implant inclination on stresses around twoimplant- retained overdentures with resilient stud attachments. Materials and Methods: Four acrylic models representing a mandibular edentulous ridge were constructed. For each model, two implants were placed at canine areas. Models were classified into four types according to the degree of buccal implant inclination: Group I (GI, 0 degrees), Group II (GII, 10 degrees), Group III (GIII, 20 degrees), and Group IV (GIV, 30 degrees). Overdentures were connected to the implants with Locator attachments. Regular light-retention inserts were used for all groups, and extended range inserts were also used for GIV (GIVext), making a fifth comparison group. Four strain gauges were bonded at the buccal, lingual, mesial, and distal surfaces of each implant to monitor the stresses during bilateral and unilateral load application. Results: Tensile stresses were recorded at distal and lingual gauges, and compressive stresses were recorded at mesial and buccal gauges for all groups. GIV recorded the highest stresses, followed by GIII, GII, GIVext, and GI. Distal position recorded the highest stresses, followed by lingual, mesial, and buccal. Nonloading side was associated with significantly higher stresses than loading side. Conclusion: The peri-implant stresses increase as the buccal implant inclination increases when resilient stud attachments are used for implant overdentures. Therefore, it is recommended to insert the implants parallel to each other to decrease peri-implant stresses. However, when buccal inclination is inevitable due to anatomical limitations, it should be limited to 10 degrees for standard nylon inserts, or extended range inserts are recommended. Keywords: implant, inclinations, Locator, overdenture, stresses

Purpose: To analyze the process of repair of bone defects in diabetic rats filled with autogenous bone and covered with membranes of homogenous bone matrix or expanded polytetrafluoroethylene (ePTFE). Materials and Methods: One hundred twenty male rats were divided into two groups: group 1 (IC), without systemic alterations (control), received an intravenous injection of citrate buffer at 0.01 M, pH 4.5; group 2 (IID) (diabetic) received an intravenous injection of streptozotocin (Sigma-Aldrich) dissolved in 0.01 M citrate buffer (pH 4.5) at a concentration of 35 mg/kg. After glycemic control was achieved, the rats were subdivided into three groups: SM (surgical cavity of the left tibia filled with autogenous bone graft, not covered by membrane); MH (surgical cavity filled with autogenous bone graft and covered with homogenous membrane); and MX (surgical cavity filled with autogenous bone graft and covered with synthetic ePTFE membrane). At 10 and 60 days, the defects in the tibiae were analyzed histologically and histometrically. Results: At 10 days, no statistically significant differences were found between the groups. However, the bone tissue of the diabetic group was qualitatively worse than that of the control group. At 60 days, a delay was found in the bonerepair process in wounds covered by the membranes regardless of the systemic state, but the quality of the newly formed bone in the wounds covered by the membranes was better in both groups. At 60 days, the diabetic group treated with homogenous membrane experienced less bone formation when compared with the nondiabetic group, and this difference was statistically significant. Such differences were even greater between the groups treated without the membrane (P .01). Conclusion: The homogenous membrane exhibited excellent biocompatibility and was incorporated into the newly formed bone in later periods, both in diabetic and nondiabetic rats. Keywords: autologous transplantation, bone grafting, diabetes mellitus, guided bone regeneration, healing, homologous transplantation

The goal of this study was to explore an innovative approach to single-tooth replacement using an individually custom-fabricated, root-analog, hybrid dental implant, in the esthetic zone, to avoid the microgap and micromovements between the implant and abutment. Moreover, the use of burs to prepare the implant recipient site is not necessary in this technique, reducing the bone removal, heating, and trauma. The process requires capturing accurate root geometry through combined computer-aided design/computerassisted manufacturing (CAD/CAM) and a three-dimensional (3D) visualization (digital volume tomography [DVT]) of the tooth in situ, which might result in reduced remodeling after insertion. A good esthetic and functional outcome was obtained. The use of a root-shaped tooth analog implant might be in selected cases a viable alternative to current threaded cylindrical and cone-shaped implants. The new concept avoids the microgap between the implant and the abutment and reduces the trauma to the tissue and bone. Keywords: immediate implant insertion, microgap, patient-individual implant design, root-analog hybrid implant, single-tooth replacement

This case report describes new implant site preparation techniques joining the benefits of using an intraoral navigation system to optimize three-dimensional implant site positioning in combination with an ultrasonic osteotomy. A report of five patients is presented, and the implant positions as planned in the navigation software with the postoperative scan image were compared. The preliminary results are useful, although further clinical studies with larger populations are needed to confirm these findings. Keywords: anatomical preservation, image-guided surgery, oral implantology, osseointegration, piezoelectric surgery, 3D implant positioning

Purpose: There is a paucity of studies that evaluate the treatment outcomes of transcrestal sinus elevation performed without using osteotomes. This study aims to evaluate the 4-year survival of short dental implants placed following transcrestal sinus elevation performed with a frontal cutting drill and to measure the marginal bone stability. Materials and Methods: Transcrestal sinus elevation was performed by sequential bone drilling using a frontal cutting drill. Short (≤ 8.5 mm) dental implants were placed. The patients' demographic data were described. Implant details, survival, marginal bone loss, and complications were analyzed. The implant survival rate was calculated using the Kaplan-Meier method. Results: Fifty-eight implants were placed in 38 patients with a mean age of 56 ± 7 years. The residual bone height was 4.6 ± 1.2 mm and bone grafting was performed for 15 implants. The mean follow-up time was 47 ± 12 months and 41 ± 9 months after insertion and loading, respectively. The implant survival rate was 96.6%, due to 2 implant failures. Cox regression analysis failed to indicate that implant length had a significant effect on the survival rate. Mesial and distal bone loss amounts were 0.9 ± 1 mm and 1.1 ± 1.0 mm, respectively. Conclusion: The use of bone drills alone to perform transalveolar sinus floor elevation is not a risk factor for implant survival and marginal bone stability. A combination of short implants and transcrestal sinus elevation can be effective in the treatment of posterior maxillae with a mean residual bone height 5 mm. Keywords: alveolar bone atrophy, implant survival, marginal bone loss, short implants, sinus floor augmentation

Purpose: Previous in vitro studies have shown that DNA oligonucleotides (ODN) can be successfully used as anchor strands for the binding and retarded release of biologically active recombinant human bone morphogenetic protein 2 (rhBMP-2). The aim of the present study was to test the hypothesis that rhBMP-2 bound to the surface of titanium implants through hybridization with nano-anchored ODN strands is biologically active and can enhance the induction of osteogenic markers in peri-implant bone in vivo. Materials and Methods: Custom-made, surface acid-etched (SAE) titanium discs and implants were coated with ODN anchor strands and subsequently hybridized with complementary ODN strands conjugated to rhBMP-2 (AS_CS_BMP-2). Discs/implants with SAE surface, ODN-coated surface (AS), and ODN-coated surface with nonconjugated rhBMP-2 (AS_BMP-2) served as controls. Release of rhBMP-2 from the coated discs was evaluated in vitro using enzyme-linked immunosorbent assay (ELISA), and bone-specific activity was assessed through pNPP turnover by induced alkaline phosphatase (AP) up to a period of 56 days. In vivo expression of bone-specific markers was analyzed after bilateral placement of coated implants into the tibiae of 36 Wistar rats (72 tibiae total). Immunostaining for AP and runt-related transcription factor 2 (Runx2) was carried out after 1, 4, and 13 weeks. Results: Release from the AS_CS_ BMP-2-coated titanium surfaces was significantly retarded compared to surfaces loaded with AS_BMP-2. The in vitro biologic activity of the released rhBMP-2 conjugates measured by AP induction was equivalent to released nonconjugated rhBMP-2. Immunostaining revealed a significant increase in the in vivo induction of AP around AS_CS_BMP-2 implants compared to the controls after 1 and 4 weeks. Conclusion: Titanium AS_CS_BMP- 2 implants can significantly enhance osteogenic differentiation in vivo in peri-implant bone in early periods of osseointegration. Keywords: biofunctionalization, BMP, controlled release, implant, oligonucleotides, osteogenic differentiation

Purpose: Biomaterials, as an alternative to autogenous bone and other biologic tissues, have been widely used in oral and maxillofacial surgery. In this context, a biomaterial that functions as a scaffold (osteoconductor), combined with a growth factor (osteoinductor), would be of great interest for clinical application. Biodegradable polymers used for slow drug release have been investigated, demonstrating good results and interesting potential. Growth hormone (GH) may be released by incorporating it into these polymers. This study aimed to evaluate cell adhesion and proliferation of a polymeric biomaterial for slow release of recombinant human GH (rhGH). Materials and Methods: Poly(lactic-co-glycolic acid) (PLGA) and PLGA/polycaprolactone (PCL) (at a 70/30 ratio of PLGA to PCL) matrices were prepared by the solvent evaporation method, combined or not with GH. Biomaterials were tested for cell adhesion and proliferation by culture in mesenchymal stem cells derived from Wistar rat bone marrow, 4',6-diamidino-2-phenylindole (DAPI) staining, and subsequent cell counting, in addition to scanning electron microscopy. Cell adhesion and proliferation was assessed at 24 and 72 hours of biomaterial exposure to culture medium. Results: All tested polymers exhibited cell adhesion and proliferation. However, PLGA-based biomaterials, especially when combined with GH, showed greater cell proliferation when the difference in growth from 24 to 72 hours was evaluated. GH appeared to modify the polymer surface, with increased roughness and microporosity. This feature was more evident in the PLGA + GH combination. Conclusion: The biomaterials tested showed pronounced cell adhesion in all test groups, and GH appeared to contribute to the increase in cell proliferation, especially when combined with PLGA as compared with pure PLGA. Further studies are required to clarify this potential for development of new biomaterials. Keywords: biocompatible materials, growth hormone, polymers