The International Journal of Oral & Maxillofacial Implants, 06/2010

Purpose: To investigate the parameters that affect primary stability of dental implants, to determine how primary stability influences posthealing stability, and to ascertain the effect of primary stability and insertion parameters on marginal bone loss. Materials and Methods: A total of 940 immediately loaded implants were considered. Using resonance frequency analysis, primary stability (primary implant stability quotient [pISQ]) and stability after 4 months (tISQ) were recorded. When the differences between pISQ and tISQ exceeded 5 units, marginal bone loss was measured. The implants were placed into three groups based on their primary stability: high (pISQ > 72), moderate, and low (pISQ 68). Changes in stability after 4 months of loading were evaluated. The relationships between pISQ, insertion parameters, ΔISQ (ie, tISQ - pISQ), and marginal bone loss were analyzed. The Student t test, one-way analysis of variance, and Spearman nonparametric correlation coefficient were employed for statistical evaluation. Results: Of the 940 implants, tISQ was recorded in 526 implants and marginal bone loss was measured in 76 implants. There was no statistical relationship between pISQ and insertion torque. Primary stability was influenced by implant diameter but not by implant length. There was a significant relationship between implant insertion torque and bone type. The low primary stability group showed a significant increase in stability during healing. However, high primary stability implants demonstrated a significant reduction in their stability. The linear regression analysis demonstrated that at a pISQ of 69.2, tISQ value would equal pISQ value. Correlations between marginal bone loss and final insertion torque and between marginal bone loss and ΔISQ values were observed. Conclusions: Stability of immediately loaded implants with high pISQ decreased significantly during the initial 4 months of healing. However, stability of implants with low primary stability increased significantly. ΔISQ and insertion torque showed correlation with marginal bone loss. Keywords: alkali treatment, dental implants, immediate loading, implant stability, insertion torque, resonance frequency analysis

Purpose: Recently, cone beam computed tomography (CBCT) was developed and applied to presurgical imaging for dental implant treatment. Because the values obtained from CBCT images are not absolute values, unlike the Hounsfield units obtained by medical CT, the relationship between the values of trabecular bone morphometry obtained in small-volume CBCT images and CT values obtained from multislice CT was evaluated in an in vitro study. Materials and Methods: Small-volume CBCT and multislice CT were performed in the posterior mandible. Subsequently, morphometric analysis of the trabecular bone in CBCT images was performed using three-dimensional bone morphometry software, and the correlations between the trabecular bone volume per total tissue volume (BV/TV) obtained using CBCT images and CT values generated from multislice CT images were analyzed. Results: BV/TV ranged from 3.1% to 42.7%, with a mean of 20.4% (SD: 11.4) when the setting was 0.5 for the threshold. The correlations between BV/TV using the threshold values ranged from 0.3 to 0.7, and CT values showed a high level of correlation (range: 0.83 to 0.93). Conclusions: The trabecular BV/TV was closely correlated with CT values obtained using multislice CT images. It was suggested that the trabecular BV/TV can be used to evaluate the density of mandibular cancellous bone in dental implant treatment. Keywords: cone beam computed tomography, dental implant, mandible, morphometric analysis, trabecular bone

Purpose: This paper reports on an in vitro comparison of osteoblast and mesenchymal stem cell (MSC) adhesion, proliferation, and differentiation related to two different surface treatments applied to the same implant design to determine whether the interaction between cells and implants is influenced by surface structure and chemical composition of the implants. Materials and Methods: Thirty-nine implants with a sandblasted (SB) surface and 39 implants with a grit-blasted and high-temperature acid-etched (GBAE) surface were used. The implant macrostructures and microstructures were analyzed by high- and low-voltage scanning electron microscopy (SEM) and by stereo-SEM. The surface chemical composition was investigated by energy dispersive analysis and x-ray photoemission spectroscopy. SaOS-2 osteoblasts and human MSCs were used for the evaluation of cell proliferation and alkaline phosphatase enzymatic activity in contact with the two surfaces. Results: The GBAE surface showed fewer contaminants and a very high percentage of titanium (19.7%) compared to the SB surface (14.2%). The two surfaces showed similar mean roughness (Ra), but the depth (Rz) and density (RSm) of the porosity were significantly increased in the GBAE surface. The GBAE surface presented more osteoblast and MSC proliferation than the SB surface. No statistically significant differences in alkaline phosphatase activity were found between surfaces for either cellular line. Conclusions: The GBAE surface showed less surface contaminants and a higher percentage of titanium (19.7%) than the SB surface. The macro/micropore structured design and chemical composition of the GBAE surface allowed greater cell adhesion and proliferation and an earlier cell spreading but did not play an obvious role in in vitro cellular differentiation. Keywords: dental implants, human mesenchymal stem cells, implant surface, SaOS-2 cells

Purpose: The purpose of this study was to evaluate the influence of different types of bone on the stress distribution in the mandibular bone supporting a prefabricated bar-type implant prosthesis using three-dimensional finite element analysis. Materials and Methods: Four finite element models (M) of a completely edentulous mandibular arch were built. The bone types varied from type 1 to type 4 (M1, M2, M3, M4). The arch was restored using a prefabricated bar system supported by four interforaminal implants for the protocol prosthesis. Computer software was used to determine the stress fields. Three unilateral posterior loads (L) of 150 N were exerted on the prosthesis: L1, perpendicular to the prefabricated bar; L2, oblique (30 degrees) in the buccolingual direction; and L3, oblique (30 degrees) in the linguobuccal direction. The maximum principal stress (δmax) and the maximum principal strain (εmax) were obtained for cortical and trabecular bone. Results: Types 3 and 4 bone showed the highest δmax (MPa) in the cortical bone (19.9 and 18.2 for L1, 34.6 and 31.3 for L2, and 3.88 and 24.4 for L3, respectively). The maximum principal strain (εmax) was observed in type 4 cortical bone for all loads (1.80 for L1, 2.4 for L2, and 2.36 for L3). Conclusions: The cortical bone in M3 and M4 showed the highest stress concentration in the axial and buccolingual loading conditions. Bone types 1 and 2 showed the lowest stress concentrations. For the linguobuccal loading condition, the cortical bone in M4 showed the highest stress concentration, followed by bone types 3, 2, and 1. Cortical bone in M4 showed the highest strain for all loading conditions. The bone type might not be the only decisive factor to influence the stress distribution the bone supporting an implant prosthesis anchored by a prefabricated bar. Keywords: biomechanics, bone, dental implants, finite element analysis, osseointegration

Purpose: The aim of this study was to evaluate, using scanning electron microscopy (SEM), the accuracy of four impression techniques for osseointegrated implants (with or without acrylic resin splinting and with irreversible hydrocolloid or polyvinyl siloxane [PVS] impression material). Materials and Methods: A metal master model was made with three implant analogs and two prosthetic spaces. This model was used as the standard for all impressions. Two impression materials were used (irreversible hydrocolloid and PVS) and two transfer techniques were used (squared impression copings indexed by the impression material and squared impression copings splinted with acrylic resin). Four groups were therefore analyzed (n = 5): IH = irreversible hydrocolloid only, IHS = irreversible hydrocolloid + splint, P = PVS only, and PS = PVS + splint. A reference framework made with palladium-silver alloy over the UCLA abutment was created on the master model. The fit of this structure to the master model was used as a reference. SEM images of the front and side gaps between the abutments and the implant analogs were created and then measured using image analysis software. Results: IH presented the largest misfit. The splinted impression copings generated a smaller marginal gap than the indexed material technique, irrespective of the impression material used. There was no significant difference between IHS, P, PS, and the reference (multivariate test, Wilks criteria). However, PS presented a standard deviation that was three times lower than those of the other groups, and its mean was closer to the reference. Conclusions: The IH impression technique was the least accurate technique. There was no difference between IHS, P, and PS techniques with regard to the reference constant. The impression techniques that used splinted impression copings generated more accurate casts, irrespective of the impression material. Keywords: dental implants, impression, irreversible hydrocolloid, polyvinyl siloxane, splinting

Purpose: This study evaluated the effect of severe magnesium (Mg) dietary deficiency on systemic bone density and biomechanical resistance of bone tissue to the removal torque of osseointegrated implants. Materials and Methods: The sample consisted of 45 rats; each received a titanium implant in their tibial metaphysis. After 60 days, the animals were divided into three groups (n = 15) according to their dietary Mg: the control group received the recommended content of Mg, group Mg1 received a 75% reduction in dietary Mg content, and group Mg2 was fed a diet with a 90% reduction in Mg content. Animals were sacrificed 150 days after implant placement. Serum concentrations of Mg were measured and the effect of Mg deficiency on systemic bone density was evaluated by densitometry of the lumbar vertebrae and femur. Biomechanical characteristics were measured by resistance of the bone tissue to removal of the implants. Results: Lower Mg serum concentrations were found for the Mg1 and Mg2 groups; however, densitometric analysis and torque evaluations showed a statistically significant difference only in the Mg2 group (P .05). There was a statistically significant difference in removal torque between the Mg2 group and the control group. Conclusions: This study showed that a severe deficiency of Mg decreased the systemic bone density and removal torque of osseointegrated implants. Keywords: bone mineral density, dental implants, magnesium deficiency, rats, removal torque

Purpose: Preparation of a one-piece dental implant abutment is often needed to achieve a proper emergence profile for a definitive restoration. However, this procedure may compromise osseointegration through the production of heat. The aim of this study was to measure heat production during implant abutment preparation with different volumes of water irrigation using a one-piece implant system. Materials and Methods: Forty-five one-piece dental implants were used in this study. The implants were divided into three groups according to the water flow rate used during abutment preparation: 30 mL/min (G30), 15 mL/min (G15), and without water irrigation (G0). Thermocouples were positioned at the most coronal and most apical threads. The abutments were prepared using a high-speed dental handpiece. Preparation continued for 120 seconds or until the implant temperature reached 47°C. Results: The time needed to reach 47°C in the most coronal thread of group G0 was 5.73 ± 1.16 seconds. After the preparation was stopped at 47°C, the temperature continued to increase until reaching a maximum temperature. None of the implants in the water irrigation groups reached 47°C. The time needed to reach maximum temperature was significantly shorter for group G0 than the groups with water irrigation. A strong positive correlation was found between coronal and apical recordings. Conclusion: Prosthetic preparation of onepiece dental implants without irrigation induced a rapid increase in temperature. Water irrigation reduced heat production during abutment preparation in a dose-dependent manner. Keywords: dental abutment, heat production, one-piece dental implant, osseointegration, preparation, water irrigation

Purpose: This aim of this study was to evaluate the effect of splinting mini-implants on marginal bone loss when used to retain mandibular overdentures. Materials and Methods: With mathematical models, a finite element analysis was performed to compare the bone stress distribution around two miniimplants, either splinted with a bar superstructure or not splinted. In the clinical portion of this study, 90 mini-implants were placed in the anterior mandibles of 45 completely edentulous patients selected from a public health center. Patients were randomly allocated into two groups. Group-ball (22 patients, n = 44) received two single ball-type mini-implants, and group-bar (23 patients, n = 46) received two mini-implants splinted with a prefabricated bar. All implants were placed using a flapless technique and loaded immediately. Marginal bone loss was assessed through standardized retroalveolar radiographs of each mini-implant and compared 5, 10, 15, and 24 months after implant placement. Results: The finite element analysis showed the highest minimum principal stress (-118 MPa) in bone surrounding the unsplinted mini-implant, while around the splinted implants the principal stresses were -56.8 MPa. After 2 years of follow-up in the clinical study, group-ball showed a trend toward greater marginal bone loss than group-bar (1.43 ± 1.26 mm and 0.92 ± 0.75 mm, respectively). Group-ball showed a significantly higher prevalence of vertical bone loss than group-bar (chi-square test, two-tailed). Conclusion: Splinted mini-implants with a rigid superstructure decrease the bone stress level in comparison with single mini-implants. The effects of bone stress magnitude may explain the clinical outcome, in which splinted mini-implants supporting a mandibular overdenture showed less marginal bone loss compared with nonsplinted mini-implants. Vertical bone resorption morphology was significantly more prevalent in the latter group. Keywords: biomechanics, marginal bone loss, mini-implant, overdentures, splinting

Purpose: Excess residual cement around the implant margin has been shown to be detrimental to the peri-implant tissue. This in vitro study examines the retentive strengths of two different cementing techniques and two different luting agents on a machined titanium abutment and solid screw implants. The amount of reduction of excess cement weight between the two cementation techniques was assessed. Materials and Methods: Forty gold castings were fabricated for 4.1 mm in diameter and 10 mm in length solid-screw dental implants paired with 5.5-mm machined titanium abutments. Twenty implants received a provisional cement, and 20 implants received a definitive cement. Each group was further divided into two groups. In the control group, cement was applied and the castings seated over the implant-abutment assembly. The excess cement was then removed. In the study group, a "practice abutment" was used to express excess cement prior to cementation. The weight of the implant-casting assembly was measured and the residual weight of cement was calculated. The samples were then stored for 24 hours at 100% humidity prior to tensile strength testing. Results: Statistical analysis revealed significant differences in tensile strength across the groups. Further Tukey tests showed no significant difference in tensile strength between the practice abutment technique and the conventional technique for both definitive and provisional cements. There was a significant reduction in residual cement weight, irrespective of the type of cement, when the practice abutment was used prior to cementation. Conclusions: Cementation of implant restorations on a machined abutment using the practice abutment technique and definitive cement may provide similar uniaxial retention force and significantly reduced residual cement weight compared to the conventional technique of cement removal. Keywords: cementation, dental cement, dental implants, tensile strength

Purpose: This in vitro study compared the dimensional accuracy of two impression techniques: Duralay splinted impression copings (D) and metal splinted impression copings (M) for implant-supported prostheses. Materials and Methods: A master cast with four parallel implant abutment analogs and a passive framework were fabricated. Vinyl polysiloxane impression material was used for all impressions with a metal stock tray. Two groups (D and M) were tested (n = 5). The measurement method employed was just one titanium screw tightened to the framework. Each group's measurements were analyzed using software that received the images of a video camera coupled to a stereomicroscope at x100 magnification. The results were analyzed statistically (t test). Results: The mean values of abutment/framework interface gaps were: master cast = 32 µm (SD 2), group D =165 µm (SD 60), and group M = 69 µm (SD 36). There was a statistically significant difference between the D and M groups (P = .001). Conclusion: Under the limitations of this study, it could be suggested that a more accurate working cast can be fabricated using metal splinted impression copings. Keywords: dental implant, implant impression technique, splinting material

Purpose: The phenomenon of developing a certain tactile sensibility through osseointegrated dental implants is called osseoperception. Active tactile sensibility can be tested by having the subject bite on test bodies. The aim of the study was to describe the active tactile sensibility of single-tooth implants based on the 50% value and the slope of the sensibility curve at the 50% value. Materials and Methods: Sixty-two subjects with single-tooth implants with natural opposing teeth were included in the study. In a computer-assisted and randomized way, copper foils of varying thickness (0 to 200 µm) were placed inter - occlusally between the single-tooth implant and the natural opposing tooth, and the active tactile perception was studied according to the psychophysical method of constant stimuli and statistically evaluated by logistic regression. Results: Tactile perception of the implants at the 50% value estimated by logistic regression was 20.2 ± 10.9 µm on average, and the slope was 29 ± 15. Regarding implant surface structure, significant differences were observed. The sandblasted and acid-etched surface was significantly more sensitive than the titanium plasma-sprayed surface, and the machined surface was similar to the titanium plasma-sprayed surface. Conclusions: Active tactile sensibility of implants with natural antagonistic teeth is very similar to that of teeth, but the slope of the tactile sensibility curve is flatter. Significant differences in tactile sensibility as a function of different implant surfaces may indicate that receptors near the implant form the basis of osseoperception. Keywords: active tactile sensibility, dental implants, interdental perception sensibility, occlusion, osseoperception, surface properties

Purpose: The aim of this study was to evaluate the effect of treatment with either two or four mandibular endosseous implants with an overdenture on mandibular posterior residual ridge resorption over a 10-year period. Materials and Methods: Sixty edentulous patients with residual mandibular height between 12 and 18 mm participated. Thirty patients were treated with an overdenture supported by two IMZ implants (group A) and 30 patients were treated with an overdenture with four IMZ implants (group B). Before treatment and 10 years after treatment, panoramic radiographs were taken and compared to ascertain possible bone loss. Proportional area measurements were used to determine changes in the mandibular posterior residual ridge bilaterally. Results: There was a statistically significant difference in mandibular posterior residual ridge resorption between the two treatment protocols. The posterior bone area index was reduced by a mean of 10% for group A and 6% for group B over 10 years. Conclusions: There was a significant difference in mandibular posterior residual ridge resorption between patients treated with either two or four implants to stabilize an overdenture. No correlation was shown between mandibular posterior residual ridge resorption and peri-implant marginal bone loss. The confounding factors of marginal bone loss around the implants, age, gender, initial mandibular height, and the number of years the patient had been edentulous failed to show a significant effect on posterior ridge resorption. Keywords: bone resorption, endosseous dental implants, mandible, overdenture, residual ridge

Purpose: The aim of this prospective study was to evaluate the concept of intraoral welding as a suitable technique for the fabrication of a restoration for the edentulous atrophic maxilla on the day of placement of axial and tilted implants. Materials and Methods: Thirty patients received three axial and four tilted implants in the edentulous maxilla. Immediately after implant placement, definitive abutments were connected to the implants and then a titanium bar was welded to them using an intraoral welding unit. This framework was used as a support for the definitive restoration, which was attached on the day of implant placement. Mean marginal bone loss and radiographically detectable alteration of the welded framework were assessed using periapical radiographs immediately after surgery and at 6, 12, 24, and 36 months after placement. Results: Sixteen men and 14 women with an average age of 58.1 years (SD 13.6) were consecutively treated with 210 immediately loaded implants. No fractures or radiographically detectable alterations of the welded frameworks were evident. A 100% prosthetic success rate was seen at 36 months. Three (1.4%) implants had serious biologic complications, resulting in success rates of 97.8% for axial implants and 99.2% for tilted implants. The accumulated mean marginal bone loss was 0.92 mm (SD 0.75; n = 90) for axial implants and 1.03 mm (SD 0.69; n = 120) for tilted implants. The average pocket probing depths were 1.87 mm (SD 0.98; n = 90) for the axial implants and 1.95 mm (SD 0.81; n = 120) for the tilted implants. Conclusions: It is possible on the day of implant placement surgery to successfully rehabilitate the edentulous atrophic maxilla with a fixed, definitive restoration supported by an intraorally welded titanium framework attached to axial and tilted implants. Keywords: immediate loading, intraoral welding, tilted implants

Purpose: The purposes of this study were to examine the incidence of buccal mucosal lesions and identify factors affecting this complication caused by an interradicular miniscrew used as orthodontic anchorage. Materials and Methods: Data from patients who used the Aarhus screw as orthodontic anchorage in the authors' practice from May 2003 to December 2008 were collected. The factors related to buccal injury during the use of miniscrews were evaluated using the Rank or Fisher exact test. Results were considered significant at P .05. Results: In all, 136 Aarhus screws in 54 patients were examined. The overall incidence of buccal lesions caused by interradicular miniscrews was 11.8%. The incidences of trauma were 10.4% in men and 12.5% in women, 9.5% in the maxilla and 12.8% in the mandible, 15.0% in patients with a high mandibular plane angle and 9.2% in patients with an average angle, and 28.1% with a miniscrew insertion angle between 10 and 30 degrees, 8.6% with an insertion angle between 30 and 60 degrees, and 4.4% with an insertion angle between 60 and 80 degrees. There were statistically significant differences according to site of placement (P = .00) and occlusogingival position (P = .00). Conclusions: Interradicular miniscrews may be associated with damage to the buccal mucosa. For buccal mucosal lesions caused by interradicular miniscrews, site of placement and occlusogingival position are the major risk factors, and the angle of placement and the mandibular plane angle are secondary risk factors. The patient's sex and the arch in which the screw is placed (maxilla versus mandible) have little effect. Keywords: anchorage, buccal mucosal lesion, mandibular plane angle, miniscrew, molars

Purpose: The success of single-tooth implant restorations has resulted in an increased use of nonsplinted implants to replace adjacent missing teeth; however, this may result in excessive force transmission to the implant and bone, causing bone loss. The purpose of this prospective study was to compare the marginal bone level change of adjacent splinted implants and of nonsplinted implants functionally loaded with cemented restorations up to 5 years in maxillae. Material and Methods: Between 2002 and 2004, all patients who received three consecutive adjacent implants in a private office and a university implant dentistry department were included in this study. All implants were placed in posterior maxillae. Maxillary left implants were restored with splinted cemented restorations, and maxillary right implants were restored with nonsplinted cemented restorations. Marginal bone resorption was measured with intraoral radiographs annually for 5 years. The data were analyzed statistically with the Mann-Whitney U test and the two-sample Kolmogorov-Smirnov test to identify differences between splinted and nonsplinted implant restorations. Results: One hundred thirty-two implants were placed in 44 patients. Two subjects (6 implants in total) did not complete the study. Three implants failed at stage-two surgery. Of the remaining 123 implants, 63 were restored with splinted cemented restorations and 60 were restored with nonsplinted cemented restorations. The mean marginal bone level changes at the 5-year recall were -0.7 ± 0.2 mm for splinted restorations and -0.8 ± 0.2 mm) for nonsplinted restorations. Conclusions: Peri-implant marginal bone loss around nonsplinted implants in the present study was statistically equivalent to that observed in splinted implants. Multiple nonsplinted implants can be successfully included in many clinical situations in an effort to optimize esthetics and circumvent the problem of nonpassively fitting frameworks. Keywords: bone level changes, dental implants, implant crowns, implant-supported prostheses, splinting

Purpose: The aim of this study was to compare implant-supported restorations placed and loaded immediately or with a delay in a longitudinal case control study. Materials and Methods: Seventy-six patients with 222 implants were enrolled in this study. One hundred eleven implants (45 patients) were submitted to immediate functional or nonfunctional loading. These were compared to 111 implants (51 patients) that received delayed loading after submerged healing. The mean observation time was 40.3 months (3.36 years). Implant success was determined, and peri-implant soft tissue parameters and esthetic outcomes for anterior restorations were evaluated. The implants were divided into four groups according to their treatment protocol: immediate (I) or delayed (D) implant placement (P) or function (F), ie: group 1 = IF+IP, group 2 = IF+DP, group 3 = DF+IP, and group 4 = DF+DP. Results: Five implants were lost during healing, giving an overall success rate of 97.7%. Implants with delayed function showed significantly better results (100.0%) than implants that were immediately loaded (95.5%). Four of the five lost implants had been placed immediately postextraction (success rate for delayed implant placement, 99.4%, versus 93.1% for immediate implant placement). Regarding the four treatment protocols, group 1 showed a success rate of 91.3%; group 2 achieved 98.5%; and both delayed function groups showed 100% success. No statistically significant difference was seen between the four groups. Esthetically significant advantages were seen for the implants placed into immediate function. Probing depths and bleeding on probing were significantly lower in the group of implants placed into immediate function. Conclusions: Implants that are loaded immediately can achieve good outcomes. However, the risk of implant loss appears to be increased in cases where immediate function is combined with immediate implant placement. Keywords: dental implants, esthetics, immediate functional loading, immediate nonfunctional loading, immediate restoration, risk accumulation

Purpose: The aims of this prospective study were to: (1) determine clinical and radiographic success and survival rates of implants placed in a staged procedure after sinus augmentation; and (2) compare the success and survival rate of implants in two patient groups with different ridge height prior to treatment (those with minimal residual crestal bone [= 3.5 mm] below the sinus and those with moderate residual crestal bone [> 3.5 mm]). Materials and Methods: The study used anorganic bovine bone-derived mineral and autogenous bone for the sagittal sandwich bone augmentation technique, a collagen membrane to protect the sinus window, and a staged approach for implant placement; all implants featured an anodized surface. Results: Two hundred forty-five implants were placed in 100 sinus sites (79 patients), and 244 have survived to date. The cumulative success and survival rates of all implants overall at 5 years were 96.5% (SE 2.0%) and 99.6% (SE 0.4%), respectively. The overall success and survival rates at 5 years for implants placed into minimal residual crestal bone were 94.1% (SE 3.4%) and 99.4% (SE 0.6%), respectively. For implants placed into moderate crestal bone, overall success and survival rates were both 100.0% (SE 0.0%). Conclusions: Success of implants placed after sinus augmentation appears similar to implants placed in native bone when a classical submerged implant healing time of 6 months is used. The success and survival rates and crestal bone remodeling of implants placed in minimal residual crestal bone were comparable to those of implants placed in moderate residual crestal bone. Keywords: clinical trial, dental implants, posterior maxilla, sinus grafting, staged procedure

Purpose: The success of zygomatic implants following the two-stage, as well as the immediate loading, concept has been well documented. This graftless approach for the treatment of the completely edentulous resorbed maxilla allows for rehabilitation with an implant-supported fixed prosthesis. The purpose of this prospective study is to report on the 7-year follow-up of patients treated with zygomatic implants in conjunction with two to four anterior maxillary implants placed into immediate function and restored with a definitive fixed prosthesis. Materials and Methods: This prospective study involved 36 patients treated with 74 zygomatic implants and 98 anterior maxillary implants supporting fixed prostheses between 2003 and 2005. Results: Two zygomatic implants in two patients were identified as mobile at stage-two surgery; replacement implants resulted in successful osseointegration. All anterior maxillary implants were determined as osseointegrated at stage two. Three patients experienced unilateral maxillary sinus infections that were refractory to oral antibiotics and were treated with functional endoscopic sinus surgery, which resolved the infections. All patients treated with the immediate loading concept were restored with definitive fixed profile prostheses as planned. Conclusion: The high survival rate, reduced morbidity, and high rate of patient acceptance for the zygomatic implant concept allowed the rehabilitation of the resorbed edentulous maxilla with fixed implant-supported prosthesis, rendering this procedure a viable and a predictable treatment option. Keywords: atrophied maxilla, edentulous maxilla, fixed maxillary prosthesis, immediate load, zygoma

Purpose: The primary goal of this study was to compare implant survival 12 months after immediate loading of single implants placed in healed ridges versus extraction sockets. Secondary outcomes were to compare marginal bone adaptation and soft tissue changes over time. Materials and Methods: A prospective multicenter clinical investigation was initiated to assess clinical performance of immediately loaded implants in the maxilla. Implant survival was ascertained at the time of impression making (8 to 10 weeks) and after 1 year by clinical stability. Radiographic marginal bone levels, soft tissue levels, and plaque and bleeding scores were compared with baseline values (implant placement and provisionalization). Results: One hundred thirty-nine patients received 157 implants in the maxilla. Single implants with provisional crowns were placed in extraction sockets of 55 patients (58 implants) and in healed ridges of 60 patients (65 implants). In addition, 19 patients (23 implants) required bone grafting prior to implant placement, and 11 implants in 10 patients among all groups were not immediately loaded because of insufficient initial stability after surgery. Three implants (5.2%) failed in extraction sites and one implant (1.5%) failed in a healed ridge. The mean change in marginal bone level 1 year after implant placement was 1.30 mm (SD 2.52) (gain) in extraction sockets and -0.40 mm (SD 1.43) (loss) in healed ridges. The mucosal zenith was stable or moved incisally following definitive crown placement in 83.7% of immediate implants and 87.0% of implants placed in healed ridges. Plaque and inflammation scores were low and did not differ between groups. Conclusions: The responses of local bone and soft tissues at immediately loaded implants placed in extraction sockets or healed ridges were similar. Furthermore, these 1-year results suggest that clinical management of esthetically critical soft tissue may be predictably achieved in both indications. Keywords: dental implants, immediate loading, immediate placement, single-tooth replacement

Purpose: A new approach for zygomatic implant placement was proposed to eliminate the risk of maxillary sinusitis related to the procedure. Materials and Methods: A prospective study of this new approach was conducted, and consecutive patients treated between June 2007 and December 2008 were included. An extended sinus lift with retained bone window was performed, such that zygomatic implants were placed completely outside the displaced maxillary sinuses. All patients were followed up radiologically at regular intervals using cone beam computed tomography to evaluate the status of the zygomatic implants and the condition of the maxillary sinuses. Results: Sixteen patients (9 women and 7 men with a mean age of 60) were treated with 37 zygomatic implants. Within the period of investigation from 6 months to 24 months, there were no failed zygomatic implants, and no instances of maxillary sinusitis were reported. Conclusions: The new approach that combined the zygomatic implant placement with the extended sinus lift procedure was predictable and fulfilled the purpose of lowering the risk of maxillary sinusitis. Keywords: bone regeneration, maxillary sinusitis, sinus elevation, sinusitis, zygomatic implants

Prosthodontic and implant treatment for a patient with polymyalgia rheumatica can be complicated not only by its symptoms, but also by the side effects of long-term use of certain medications, particularly systemic glucocorticoids. This clinical report presents a polymyalgia rheumatica patient who required full-mouth rehabilitation with dental implants. The patient had a sensitive gag reflex and refused the use of any removable prostheses. She presented clinically with a skeletal Class II malocclusion with severe overbite and overjet. All her remaining dentition was determined to be unrestorable. Full-mouth extractions and immediate placement of implants followed by early implant loading were performed. The use of systemic glucocorticoids might have exacerbated her type 4 maxillary bone and compromised her healing capacity and consequently made implant surgery challenging. Her treatment with full-arch fixed implant-supported dentures to correct her severe overbite and overjet and manage misaligned dental implants is summarized here. The effects of polymyalgia rheumatica in prosthodontic and dental implant treatments are reviewed and discussed. Keywords: dental implants, full-mouth reconstruction, polymyalgia rheumatica, systemic glucocorticoids

Purpose: The purpose of this case series was to evaluate the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) in an absorbable collagen sponge (ACS) carrier for the repair of significant bone defects following tooth removal. The surgical technique was modified because primary closure was not obtained over the grafted sockets. Materials and Methods: The present series included 10 consecutively treated patients with failed endodontically treated maxillary central incisors. Computed tomographic scans were obtained preoperatively. The extraction sockets all had > 50% buccal bone loss. The sockets were grafted with rhBMP-2/ACS and a small amount of bone substitute. Dental implants were inserted after 4 to 6 months of healing. Results: Healing of the grafted sockets was uneventful. Dental implants were placed in all grafted sites without the need for further bone augmentation. A comparison of preoperative and postgrafting computed tomographic scans found a slight loss in alveolar width at the crest of 1.07 mm. Connective tissue grafts were placed in five patients. All 10 implants integrated well and were restored with single crowns. Conclusions: The use of rhBMP-2/ACS was effective in repairing osseous defects prior to implant placement. The lack of primary closure over the graft did not appear to complicate healing or compromise bone growth. This modification simplifies the technique and may reduce postoperative morbidity caused by flap manipulation. Keywords: bone graft, dental implants, extraction socket, recombinant human bone morphogenetic protein-2