International Journal of Oral Implantology, 04/2011

Objectives: To evaluate whether 6.3 mm-long implants could be a suitable alternative to longer implants placed in vertically augmented atrophic posterior mandibles. Materials and methods: Sixty partially edentulous patients having 7 to 8 mm of residual crestal height and at least 5.5 mm thickness measured on CT scans above the mandibular canal were randomised according to a parallel group design either to receive 1 to 3 submerged 6.3 mm-long implants or 9.3 mm or longer implants (30 patients per group) placed in vertically augmented bone. Bone was augmented with interpositional anorganic bovine bone blocks covered by resorbable barriers. Grafts were left to heal for 5 months before implant placement. Four months later, provisional acrylic prostheses were delivered, and were then replaced after another 4 months by definitive metal-ceramic prostheses. Outcome measures were prosthesis and implant failures, complications, and radiographic peri-implant marginal bone level changes. All patients were followed up to 3 years after loading. Results: Four patients dropped out, two from each group. The augmentation procedure failed in two patients and only 6.3 mm-long implants could be inserted. There were no statistically significant differences for prosthesis and implant failures. Three prostheses could not be placed or had to be remade in the short implant group versus 4 prostheses in the augmented group. Two short implants failed versus 3 long implants, all in different patients. There were statistically significantly more complications in augmented patients (22 complications in 20 augmented patients versus 5 complications in 5 patients of the short implant group). Both groups gradually lost peri-implant bone in a statistically significant way at 4 months, and 1 and 3 years after loading. Three years after loading, patients of the short implant group lost an average of 1.24 mm of peri-implant bone compared with 1.76 mm in the long implant group. Short implants experienced statistically significantly less bone loss (0.52 mm; CI 95% 0.20 to 0.83, P = 0.002) than long implants. Conclusions: When residual bone height over the mandibular canal is between 7 and 8 mm, 6.3 mm short implants could be an interesting alternative to vertical augmentation since the treatment is faster, cheaper and associated with less morbidity. Longer follow-ups are needed to confirm these results. Schlagwörter: bovine anorganic bone, inlay graft, short dental implants, sinus lift, vertical augmentation

Objectives: To evaluate whether the adjunctive use of a bone substitute at immediate single implants placed in fresh extraction sockets with a residual buccal bone-to-implant gap of at least 1 mm could improve the aesthetic outcome of guided bone regeneration (GBR). Materials and methods: Eighty patients requiring bone augmentation at a single immediate postextractive implant to improve the aesthetic outcome were randomly allocated to an augmentation procedure using a resorbable barrier alone (GBR group; 40 patients) or a bone substitute plus a resorbable barrier (GBR + BS group; 40 patients) according to a parallel group design at four different centres. Three to 4 months after implant placement/augmentation, implants were loaded with provisional or definitive single crowns. Outcome measures were implant failures, complications, aesthetics assessed using the pink esthetic score (PES), patient satisfaction and peri-implant marginal bone levels, recorded by blinded assessors. All patients were followed up to 1 year after loading. Results: One patient dropped out from the GBR group. Seven (9%) implants failed: 2 (5%) in the GBR + BS group and 5 (12.5%) in the GBR group. Six minor complications occurred in the GBR + BS group versus 2 in the GBR group. These differences were not statistically significant. Just after implant placement/augmentation, mean bone levels were -0.21 mm at GBR + BS implants and -1.92 mm at GBR implants whereas at 1 year after loading they were -1.04 and -1.76, respectively. When comparing the two groups, GBR + BS implants had 0.70 mm more peri-implant marginal bone than GBR implants. Aesthetics was scored by a blinded assessor as statistically significantly better for the GBR + BS group. Patients were equally satisfied. There were no differences between centres regarding the clinical outcomes. Conclusions: The use of additional anorganic bovine bone substitute (Endobon) with resorbable collagen barriers (OsseoGuard) in defects around post-extractive implant improves the aesthetic outcome, though single post-extractive implants might be at a higher risk for implant failures. Schlagwörter: guided bone regeneration, post-extractive implants

Purpose: To compare the effectiveness of immediate post-extractive single implants with delayed implants placed in preserved sockets after 4 months of healing. Implants that achieved an insertion torque of at least 35 Ncm were immediately non-occlusally loaded. Materials and methods: Just after tooth extraction and in the presence of a loss of the buccal plate bone less than 4 mm, compared to the palatal wall, 106 patients requiring a single immediate postextractive implant in the maxilla from second premolar to second premolar were randomly allocated to immediate implant placement (immediate group; 54 patients) or to socket preservation using anorganic bovine bone covered by a resorbable collagen barrier (delayed group; 52 patients) according to a parallel group design at three different centres. Bone-to-implant gaps were to be filled with anorganic bovine bone, however this was not done in 17 patients (corresponding to 40% of those who should have been grafted). Four months after socket preservation, delayed implants were placed. Implants placed with an insertion torque >35 Ncm were immediately loaded with non-occluding provisional single crowns, replaced, after 4 months, by definitive crowns. Outcome measures were implant failures, complications, aesthetics assessed using the pink esthetic score (PES), and patient satisfaction, recorded by blinded assessors. All patients were followed up to 4 months after loading. Results: Nineteen (35%) implants were not immediately loaded in the immediate group versus 39 (75%) implants in the delayed placement group because an insertion torque >35 Ncm could not be obtained. No patient dropped out. Two implants failed in the immediate group (4%) versus none in the delayed group. More minor complications occurred in the immediate group (8) than the in the delayed group (1) and this was statistically significant (P = 0.032). At delivery of definitive crowns, 4 months after loading, aesthetics were scored as 12.8 and 12.6 in the immediate and delayed groups, respectively. There was no statistically significant difference (P = 0.5). Patients of both groups were equally satisfied. Conclusions: There were more complications at immediate post-extractive implants when compared to delayed implants. The aesthetic outcome appears to be similar for both groups and it seems more difficult to obtain a high insertion torque in sockets preserved with anorganic bovine bone. Schlagwörter: delayed, immediate, post-extractive implants

Purpose: To compare the biological, technical and aesthetic outcomes of single implant-supported all-ceramic versus metal-ceramic crowns. Materials and methods: Thirty-six patients with premolar agenesis were randomly treated with 38 all-ceramic (AC) and 37 metal-ceramic (MC) implant-supported single-tooth restorations. A quasirandomisation of consecutively included restorations in patients with one or more implants was used, i.e. a combination of parallel group (for 13 patients with one restoration) and split-mouth (for 23 patients with >=2 restorations). All patients were recalled for baseline and 1-year followup examinations. Biological and technical outcomes, including complications, were clinically and radiographically registered. The Copenhagen Index Score and visual analogue scale (VAS) score were used to assess professional and patient-reported aesthetic outcomes, respectively, by blinded assessors. Results: One-year after loading, no patient dropped out and no implant failed, though one MC restoration had to be remade. The marginal bone loss was not significantly different between AC and MC restorations (AC: mean 0.08 mm, SD 0.25; MC: mean 0.10 mm, SD 0.17). Seven out of 10 inflammatory reactions were registered at AC restorations. Two technical complications, one loss of retention and one chipping of veneering porcelain were recorded at two metal-ceramic crowns. The marginal adaptation of the all-ceramic crowns was significantly less optimal than the metal-ceramic crowns (P = 0.014). The professional-reported colour match of all-ceramic crowns was significantly better than metal-ceramic crowns (P = 0.031), but other aesthetic parameters as well as the VAS scores demonstrated no statistically significant difference between AC and MC restorations. Conclusions: Marginal bone loss and the aesthetic outcomes were not significantly different between AC and MC restorations in this short-term follow-up study, though inflammatory reactions in the peri-implant mucosa as well as less optimal marginal adaptation were more frequently registered for all-ceramic compared to the metal-ceramic crowns. Schlagwörter: all-ceramic crowns, dental implants, metal-ceramic restorations, randomised controlled trial, zirconia abutments

Purpose: The aim of this ongoing prospective study was to determine the 5-year survival rate of short porous implants in the posterior atrophic mandible. Materials and methods: In 40 partially edentulous patients, 55 short porous implants were placed. The implants used were of two lengths (5 and 7 mm) and two different diameters (4.1 and 5 mm) and were chosen according to the available crestal height and width. The unloaded healing period was 4 months. Twenty-one implants were restored with single crowns, 32 were splinted to the adjacent implant, 2 were used with an overdenture and were followed for 5 years. Outcome measures were prosthesis failures, implant failures and complications. Results: No patients dropped out. Nine implants were removed: 1 implant at uncovering and 8 after prosthetic loading. Eight patients lost 1 implant and 1 patient lost 2 implants. Four crowns failed. No complications occurred during the healing period. In 2 patients severe peri-implantitis occurred after loading and the implants had to be removed. At the end of the follow-up period the survival rate was 84% at implant level and 80% at patient level. Conclusions: The use of short porous implants showed an acceptable clinical outcome in the treatment of the posterior mandible in this interim 5-year report. These preliminary results must be confirmed by longer follow-ups. Schlagwörter: implant prosthesis, posterior mandible, short dental implants

Purpose: The objective of this controlled exploratory cross-sectional study was to investigate and compare the presence of gene expression of bone resorption/remodelling in peri-implant crevicular fluid samples from healthy subjects and subjects showing obvious clinical and radiographic signs of peri-implantitis. Materials and methods: Peri-implant crevicular fluid (PICF) was sampled from seven healthy subjects and seven subjects with obvious clinical signs of peri-implantitis using paper points. The samples were analysed by quantitative polymerase chain reaction (qPCR). Biomarkers associated with bone degradation/remodelling, such as tartrate-resistant acid phosphatase (TRAP), dickkopf-related protein- 1 (DKK-1), osteoprotegerin (OPG), cathepsin K (CatK) and osteocalcin (OC), were of particular interest in the study. Results: The measured levels of genetic markers were similar for the subjects in the healthy and the peri-implantitis group. Only one subject out of seven with strong and clear clinical signs of periimplantitis exhibited a panel of genetic markers for ongoing bone degradation. This subject was also diagnosed with rheumatoid arthritis. Conclusion: The present data showed that patients with obvious clinical signs of peri-implantitis and a history of bone loss can exhibit similar gene expressions of bone loss/remodelling as clinically healthy implant patients. Absence of bone resorption markers demonstrated that it was not possible to establish ongoing bone degradation in six of seven subjects in the peri-implantitis group. The results suggest that bone resorption was not in progress at the time of PICF sampling, or that cells expressing such markers were not present in significant numbers at the site of PICF sampling. Schlagwörter: bone resorption, diagnosis, peri-implantitis, qPCR