International Journal of Oral Implantology, 04/2019

Purpose: To analyse and compare the dimensional changes of unassisted extraction sockets with alveolar ridge preservation (ARP) techniques and investigate any factors that impact the resorption of the alveolar bone. Materials and methods: A systematic search was conducted to identify randomised clinical trials (RCTs). All data were extracted, and a meta-analysis was performed for the changes in all buccolingual ridge width, midbuccal and midlingual ridge height, and mesial and distal ridge height, and horizontal width at reference points apical to the crestal area. Results: Based on 14 RCTs, the effectiveness of ARP in reducing the dimensions of the postextraction alveolar socket was confirmed. The clinical magnitude of this effect was 1.95 mm in the buccolingual ridge width, 1.62 mm in the midbuccal ridge height, and 1.26 mm on the midlingual ridge height. Additionally, 0.45 mm and 0.34 mm for mesial and distal ridge height, and 1.21 mm, and 0.76 mm for ridge width changes at points 3 and 5 mm apical to the crest were noted. Meta-regression analyses revealed that the reflection of flaps and primary wound coverage during ARP may have detrimental effects on bone remodelling, while no statistical significance was observed for any of the bone graft substitutes or the percentage of molar sockets. Conclusions: Regardless of the protocol, ARP can only minimise ridge resorption. ARP is most effective on horizontal ridge width, providing the most benefit coronally (approximating the crest), followed by the midbuccal ridge height. Keywords: alveolar bone atrophy, bone remodelling, soft graft, tooth extraction, tooth socket onflict of interest statement: The authors do not have any financial interests either directly or indirectly in the companies whose materials were evaluated in this study. This manuscript was partially supported by the University of Michigan Periodontal Graduate Student Research Fund. This systematic review was presented at the Mini-Invasivity vs Traditional Approach in Periodontology and Implantology - Consensus Conference, 20-22 September 2018, Naples, Italy.|

Purpose: The purpose of the present systematic review was to investigate at the histological level if a modified titanium surface abutment could affect the behaviour of soft peri-implant tissue (connective tissue adhesion and soft tissue inflammation). Materials and methods: An electronic databases research (MEDLINE/PubMed, Scopus, Web of Science, Cochrane Library) until 24 June 2019 for randomised controlled trials (RCTs), controlled clinical trials and non-randomised studies of interventions (NRSI) was performed. The focused question was: "In healthy patients with at least one titanium healing abutment connected to a dental implant, is the effect of a healing abutment surface modification different from machined titanium at the histological level?" The Cochrane Handbook for Systematic Reviews of Interventions to assess the risk of bias in individual studies was used for RCTs. The Newcastle-Ottawa quality assessment scale was used to evaluate NRSI. Results: In total, 192 records were evaluated for titles and abstracts. Seven studies were included in the review. Five of them reported an enhanced soft tissue adhesion in the modified abutment group without increasing the soft tissue inflammation. One study reported no significant differences among titanium-modified (double acid-etched) and titanium-machined groups. One author demonstrated at the 6-month follow-up period a higher level of inflammation around acid-etched surfaces, with a higher number of T and B lymphocytes and expression of vascular endothelial growth factor. Conclusions: Short-term data ( 6 months) suggested an enhanced connective fibre attachment next to titanium abutments with a modified surface and a similar inflammatory response, in comparison with machined surface titanium abutments. However, modified surfaces may lead to a long-term increased risk of a higher degree of inflammation in the peri-implant tissues. Due to limited available evidence, further long-term studies are needed to confirm these results. Keywords: abutment, prosthetic materials, soft tissue management, soft tissues, systematic review Conflict-of-interest statement: All authors declare that there are no conflicts of interest relating to this study.

Purpose: To compare the clinical outcomes of immediate versus conventional delayed loading of four dental implants in edentulous mandibles with fixed prostheses. Materials and methods: A blinded, two-arm, parallel group, randomised controlled trial was conducted. A total of 42 patients were included, and each received four Brånemark System implants with a TiUnite surface. The patients were randomly assigned to two study arms: 1) immediate-loading arm (IL), in which the mandibular denture was converted into an interim implant-supported fixed prosthesis (ISFP) on the day of surgery, with a permanent ISFP being inserted at least 3 months postsurgery; 2) conventional-loading arm (CL), in which the mandibular removable prosthesis was relieved at the implant site and relined with a soft tissue conditioner. Only implants with a minimum insertion torque of ≥ 35 Ncm were included in the IL group. Implants were loaded 4 to 6 months postsurgery. Independent, blind investigators assessed the patients at 2, 6 and 12 months and at 10 years. The outcome measures were prosthesis and implant success rates, type and frequency of complications and changes in peri-implant marginal bone levels. Results: A total of 20 patients were allocated to the IL group and 22 to the CL group. However, one patient from the IL arm was excluded and three patients were reallocated to the CL arm. Two implants in one patient and one in another patient could not be placed with a ≥ 35 Ncm insertion torque, and a third patient developed severe sudden gag reflex and thus it was not possible to load the implants immediately. At a later stage, one of the patients who failed the initial stability test dropped out of the study. Therefore, initially, 24 patients were conventionally loaded and 16 patients were immediately loaded. At the 10-year follow-up, six patients dropped out from the IL arm and two from the CL arm. Also, at the 10-year-follow-up, the CL and IL study arms consisted of 22 and 10 participants, respectively, using the per-protocol (PP) analysis. Six implants failed in two patients of the CL arm (two implants in one patient and four implants in another patient), and three implants failed in three patients in the IL arm (PP analysis), respectively. The patient-level implant failure rate was 10% (intention-to-treat [ITT] analysis) and 14% (PP analysis) in the CL arm, and 25% (ITT) and 20% (PP) in the IL arm. The difference was not statistically significant (95% CI from −0.18 to 0.39, P = 0.65). The failure rate at the implant level was 8% (ITT) and 8% (PP) in the CL arm, and 6% (ITT) and 5% (PP) in the IL arm. The difference was not statistically significant (95% CI from −0.06 to 0.14, P = 0.44). Ten years after loading, patients in the IL arm lost an average of 0.55 ± 0.64 mm of peri-implant bone versus 0.41 ± 0.40 mm of peri-implant bone loss observed in the CL arm. The 10-year bone loss in both arms was statistically significant compared with the baseline (P 0.001). However, there was no statistically significant difference between the two arms for peri-implant bone level changes (the difference between the arms was 0.14 mm ± 0.50 mm; 95% CI -0.23 to 0.52; P = 0.43). One prosthesis failed due to the loss of all four implants in one patient of the CL arm. Eight patients from the IL arm were affected by 13 complications (such as pain from fractures and inflammation) versus seven patients (10 complications) from the CL arm. The complication rate was 67% in the IL arm and 35% in the CL arm. The difference in complication proportions between the two arms was not statistically significant (difference in proportions = 0.32; 95% CI = -0.08 to 0.61; P = 0.14). All complications were managed successfully. Conclusions: Long-term data of immediate loading of four dental implants with a mandibular fixed prosthesis revealed comparable clinical outcomes to conventional loading. Therefore, immediate loading should be considered in the treatment of edentulous patients. Keywords: dental implants, immediate loading, mandible, prosthesis Conflict of interest statement: The study was supported by the Nobel Biocare Graduate Students Grant, Gothenburg, Sweden.

Purpose: To compare the 3-year outcomes of immediately loaded and one-stage conventionally loaded variable-thread tapered implants in the posterior maxilla. Materials and methods: This study was designed as a split-mouth randomised controlled trial. Twenty-six patients attending the postgraduate Periodontics Department at the Lebanese University, and missing teeth bilaterally in the posterior maxilla were randomised. All patients received three to four implants in each of the posterior sextants. The implants on one side were immediately loaded with a provisional resin fixed partial denture on definitive multi-unit abutments regardless of their primary stability. The implants in the contralateral side received definitive multi-unit abutments according to the one-stage unloaded protocol. Three to 3.5 months following implant placement, the implants were restored with metal-ceramic fixed prostheses. Outcome measures were implant and prosthesis failure rates, complications, and peri-implant bone level changes up to 3 years following delivery of the definitive prosthesis. The clinical outcomes and radiographic measurements were performed by a single outcome assessor blinded to the type of interventions. Results: Two patients dropped out prior to the delivery of definitive prostheses. The results were analysed using a per-protocol analysis and included 24 patients. Four implants supporting a four-unit immediately loaded prosthesis failed in one patient, 3 months following definitive prosthesis. In the same patient, the three contralateral conventionally loaded implants failed 14 months after definitive prosthesis. There were no significant differences in the proportions of implant and prosthesis failures at 3 years (difference = 0%; 95% CI 0.0% to 14.2%; P = 0.999). Peri-implantitis was diagnosed at two adjacent conventionally loaded implants in one patient at the 3-year examination. In the immediately loaded group, four early minor prosthetic complications occurred during the provisionalisation phase. Following delivery of the definitive prostheses, one minor ceramic fracture was observed in each of the implant groups. The difference in the rate of complications between the two interventions was not statistically significant at 3 years (difference = 13%; 95% CI 3.4% to 27.7%; P = 0.453). The 3-year peri-implant marginal bone level changes were evaluated in 23 patients (77 immediately loaded and 76 conventionally loaded implants). On average, patients lost 0.79 (0.62) mm at the immediately loaded and 0.91 (0.82) mm at the conventionally loaded implants, the difference being statistically not significant (difference = 0.12 mm; 95% CI −0.31 to 0.55 mm; P = 0.590). The 3-year marginal bone level changes were not significantly different between smokers (n = 12) and non-smokers (n = 11) (difference = 0.19 mm; 95% CI −0.24 to 0.62 mm; P = 0.382). Conclusions: Immediate loading of three- to four-unit fixed partial prostheses supported by variable-thread implants in the posterior maxilla can achieve similar 3-year results to one-stage conventionally loaded implants. Keywords: immediate loading, maxilla, randomised controlled clinical trial, smoking, variable thread tapered implant Conflict of interest statement: This study was independently designed by the investigators but was supported by Nobel Biocare Services, Kloten, Switzerland (grant number 2010-954) in the form of free surgical kits, implants and prosthetic components. No other financial contribution was received by any of the authors or their institutions. The authors declare that there is no affiliation or any other conflict of interest to the sponsor and that Nobel Biocare did not in any way interfere with the conduct of the trial or the publication of its results.

Purpose: This prospective, randomised, controlled clinical trial evaluated the relationship between alveolar ridge dimensional change and recession with the implant position (horizontal and vertical) and tissue phenotype in immediately placed and provisionalised implants without the use of bone grafting. Materials and methods: Patients (n = 40) with a hopeless maxillary anterior tooth received an immediate implant and immediate provisional or customised healing abutment after flapless extraction. Implants were finally restored 3 months after placement and followed up for 6 months after delivery of the restoration. The alveolar ridge dimensional change and recession were measured using cone beam computed tomography (CBCT) scans and digitalised dental casts. Alveolar contour changes were correlated to implant position and tissue phenotype. Results: The tissue phenotype showed no significant correlation to the alveolar ridge dimensional change. At 6 months, the average alveolar ridge dimensional change was approximately 0.7 mm in the buccolingual dimension independent of tissue phenotype. A statistically significant difference was observed on the recession values comparing tissue phenotypes, with more recession observed in the thin phenotype (1.96 mm) than in the thick phenotype (1.18 mm). A significant correlation was observed between horizontal implant position and buccolingual alveolar ridge change. A positive correlation was observed between the horizontal implant position and the dimensional change measured in the casts at the level of the free gingival margin. A statistically significant negative correlation was observed between the horizontal implant position and the resorption measured by the CBCT scans. Conclusions: Patients with thin tissue phenotype had a more marked recession. The horizontal implant position showed a relationship to the alveolar ridge dimensional changes observed. The greater the buccal gap distance between the implant and the buccal plate, the lesser the radiographic changes observed in the alveolar bone, however, the greater the changes observed in the buccal aspect of the casts at the level of the free gingival margin. Keywords: alveolar ridge dimension, immediate implants, peri-implant mucosa, soft tissue aesthetics Conflict of interest statement: This study was funded by Keystone Dental. Dr Tarnow is a consultant for Keystone Dental and Dr Bittner has lectured for Keystone Dental. The remaining authors have no financial interest in the companies whose materials were included in this article.

Purpose: To compare the outcomes of implants inserted in maxillary sinuses augmented with 100% anorganic bovine bone (ABB) grafts versus mixed with 50% ABB and 50% autologous bone graft using a lateral window approach. Materials and methods: This study was designed as a randomised controlled trial of parallel groups. Patients in need of an implant-supported prosthesis in maxillary posterior areas, with a residual alveolar bone height ranging between 0 and 4 mm, were recruited for lateral sinus grafting and implant placement. Patients were randomly allocated to receive two different graft materials according to a parallel group design: group A was grafted with 50% ABB and 50% autogenous bone; group B was grafted with 100% ABB. After 7 months, tapered implants were inserted with an insertion torque between 20 and 45 Ncm. Three months later implants were loaded with screw-retained temporary crowns. Definitive crowns were delivered after 3 months. Outcome measures were implant and prosthesis survival rates, complications, radiographic marginal bone-level changes, probing pocket depths (PPDs) and bleeding on probing (BOP). Clinical data were collected at definitive prosthesis delivery, and 1, 2 and 5 years after definitive loading. Results: Thirty-two consecutive patients were treated with 32 sinus elevation procedures (16 group A, 16 group B). A total of 46 implants were inserted. One patient (with two implants) dropped out in group A, and two patients (with three implants) dropped out in group B. No implant/crown failed by the end of the study. Three complications (one sinus membrane perforation and two chipping of the ceramic) were observed in three patients in group A, versus none in group B (relative risk was 0.81; 95% CI 0.64-1.03; P = 0.225). At the 2-year follow-up, the mean marginal bone loss was 1.18 ± 0.50 mm (95% CI 0.95-1.45 mm) in group A and 1.28 ± 0.48 mm (95% CI 0.97-1.43 mm) in group B, with no statistically significant differences between the two groups (difference 0.11 ± 0.22 mm; 95% CI −0.06-0.16 mm; P = 0.586). At the 5-year follow-up, the mean marginal bone loss was 1.37 ± 0.48 mm (95% CI 1.13-1.86 mm) in group A and 1.42 ± 0.48 mm (95% CI 1.17-1.90 mm) in group B (difference 0.15 ± 0.08 mm; 95% CI 0.10-0.22 mm; P = 0.426). At the 2-year follow-up, the mean PPD value was 2.70 ± 0.39 mm for group A and 2.54 ± 0.66 mm for group B, with no statistically significant difference between groups (difference 0.17 ± 0.39 mm; 95% CI 0.06-0.32 mm; P = 0.456). At the 5-year follow-up, the mean PPD value was 3.20 ± 0.44 mm for group A and 3.32 ± 0.49 mm for group B (difference 0.12 ± 0.43 mm; 95% CI 0.02-0.22 mm; P = 0.672). At the 2-year follow-up, the mean BOP value was 1.21 ± 0.79 for group A and 1.28 ± 0.68 for group B (difference 0.06 ± 0.49; 95% CI −0.23-0.25; P = 0.297), and at the 5-year follow-up, the mean BOP value was 1.77 ± 0.62 for group A and 1.91 ± 0.48 for group B (difference: 0.14 ± 0.51; 95% CI −0.05-0.33; P = 0.492). Conclusions: Within the limitations of this study, the present data confirm similar clinical outcomes of implants inserted in sinuses grafted with ABB versus implants inserted in sinuses grafted with mixed 50% ABB and 50% autologous bone. Keywords: anorganic bovine bone, atrophic maxilla, autologous bone, dental implant, sinus elevation Conflict of interest statement: This study was not supported by any company. All the authors declare no conflict of interest.

Purpose: This prospective study aims to evaluate the clinical outcomes of 'All-on-four' rehabilitations in controlled human immunodeficiency virus (HIV)-positive patients. Materials and methods: Edentulous patients requiring an implant prosthetic restoration of one or both jaws were enrolled in the present study. Each patient received at least one fixed full-arch prosthesis. Four implants, immediately loaded, were placed in each jaw using the 'All-on-four' protocol. Marginal bone loss, implant and prosthetic failure, biological and mechanical complications, and serological levels (CD4 cell count, CD4/CD8 ratio, and HIV viral load) were recorded up to 7-year follow-up. Results: A total of 116 implants were placed in 24 patients, and 29 rehabilitations based on the 'All-on-four' concept were achieved. Implant failures were registered in four patients (10 of 116 implants), and the implant survival rate was 91.37%. At the 7-year radiographic evaluation, peri-implant crestal bone loss averaged 1.91 ± 1.3 mm for upright maxillary implants (n = 30 implants) and 1.79 ± 1.28 mm for tilted maxillary implants (n = 30 implants). In the mandible, mean peri-implant crestal bone loss was 1.54 ± 1.27 mm for upright implants (n = 28) and 1.5 ± 1.3 mm for tilted implants (n = 28). No statistically significant correlation was found between serological parameters and marginal bone levels at 6 months, or through 7 years of annual follow-up (P > 0.05). A statistically significant linear correlation (P 0.001) was found between early implant failure and HIV viral load. The CD4/CD8 ratio was significantly correlated with late implant failure (P = 0.009). Conclusions: Within the limitations of this prospective 7-year longitudinal study, HIV-positive patients with a stable immune system can be candidates for the 'All-on-four' treatment concept. Keywords: dental implant, HIV-patients, immediate loading, oral rehabilitation, tilted implant Conflict of interest statement: The authors declare there are no conflicts of interest.