Group 4 ITI Consensus Report: Risks and biologic complications associated with implant dentistry.

OBJECTIVES: The aim of Working Group 4 was to address topics related to biologic risks and complications associated with implant dentistry. Focused questions on (a) diagnosis of peri-implantitis, (b) complications associated with implants in augmented sites, (c) outcomes following treatment of peri-implantitis, and (d) implant therapy in geriatric patients and/or patients with systemic diseases were addressed. MATERIALS AND METHODS: Four systematic reviews formed the basis for discussion in Group 4. Participants developed statements and recommendations determined by group consensus based on the findings of the systematic reviews. These were then presented and accepted following further discussion and modifications as required by the plenary. RESULTS: Bleeding on probing (BOP) alone is insufficient for the diagnosis of peri-implantitis. The positive predictive value of BOP alone for the diagnosis of peri-implantitis varies and is dependent on the prevalence of peri-implantitis within the population. For patients with implants in augmented sites, the prevalence of peri-implantitis and implant loss is low over the medium to long term. Peri-implantitis treatment protocols which include individualized supportive care result in high survival of implants after 5 years with about three-quarters of implants still present. Advanced age alone is not a contraindication for implant therapy. Implant placement in patients with cancer receiving high-dose antiresorptive therapy is contraindicated due to the associated high risk for complications. CONCLUSIONS: Diagnosis of peri-implantitis requires the presence of BOP as well as progressive bone loss. Prevalence of peri-implantitis for implants in augmented sites is low. Peri-implantitis treatment should be followed by individualized supportive care. Implant therapy for geriatric patients is not contraindicated; however, comorbidities and autonomy should be considered.

Influence of particle size of deproteinized bovine bone mineral on new bone formation and implant stability after simultaneous sinus floor elevation: a histomorphometric study in minipigs.

BACKGROUND: Deproteinized bovine bone mineral (DBBM) is one of the best-documented bone substitute materials for sinus floor elevation (SFE). PURPOSE: DBBM is available in two particle sizes. Large particles are believed to facilitate improved neoangiogenesis compared with small ones. However, their impact on the rate of new bone formation, osteoconduction, and DBBM degradation has never been reported. In addition, the implant stability quotient (ISQ) has never been correlated to bone-to-implant contact (BIC) after SFE with simultaneous implant placement. MATERIALS AND METHODS: Bilateral SFE with simultaneous implant placement was performed in 10 Göttingen minipigs. The two sides were randomized to receive large or small particle size DBBM. Two groups of 5 minipigs healed for 6 and 12 weeks, respectively. ISQ was recorded immediately after implant placement and at sacrifice. Qualitative histological differences were described and bone formation, DBBM degradation, BIC and bone-to-DBBM contact (osteoconduction) were quantified histomorphometrically. RESULTS: DBBM particle size had no qualitative or quantitative impact on the amount of newly formed bone, DBBM degradation, or BIC for either of the healing periods (p > 0.05). Small-size DBBM showed higher osteoconduction after 6 weeks than large-size DBBM (p < 0.001). After 12 weeks this difference was compensated. There was no significant correlation between BIC and ISQ. CONCLUSION: Small and large particle sizes were equally predictable when DBBM was used for SFE with simultaneous implant placement.

Problems related to an intraoral approach for experimental surgery on minipigs.

The purpose of the present study was to compare block and particulated bone grafts for jaw augmentation in combination with immediate implant placement. Bone defects measuring 10 mm x 10 mm x 30 mm were prepared on each side of the mandible of eight minipigs. After a healing period of 3 months, the defects in four animals were augmented with iliac crest grafts as a block or particulated graft, combined with immediate implant insertion. Clinical inspection was performed after 14 days. Complete exposure of grafts and implants was discovered. The surgical procedures were altered in the fifth animal. Inspection was made after 4 days showing no alterations. However, after another 7 days, grafts and implants were exposed. Consequently, the study was discontinued and all eight animals were killed. It is concluded that an intraoral approach is not applicable for this type of experimental surgery in minipigs. This paper describes some of the presumed reasons for the failure of the study.

Influence of particle size of autogenous bone grafts on the early stages of bone regeneration: a histologic and stereologic study in rabbit calvarium.

PURPOSE: The aim of this study was to investigate the influence of particle size of autogenous bone grafts on the early stages of bone regeneration. MATERIALS AND METHODS: Bicortical skull bone defects were prepared in 15 rabbits (4 in each rabbit). Two defects were filled at random with either small (0.5 to 2 mm3) or large (10 mm3) autogenous bone particles. In addition, 1 defect was left unfilled (control defect). All defects were covered bicortically by expanded polytetrafluoroethylene membranes. The animals were divided randomly into 3 groups and sacrificed after 1, 2, and 4 weeks, respectively. Histologic and stereologic evaluations were performed after the sections were blinded. RESULTS: No significant differences in total vessel surface area could be identified among the 3 groups. The total volume of newly formed bone in defects with small particles was larger and more mature compared to defects with large particles after 2 and 4 weeks. Furthermore, the resorption of small particles was more pronounced after 4 weeks, documenting a higher level of bone substitution compared to large particles. DISCUSSION: The early stages of bone regeneration were influenced by the particle site of autogenous bone grafts. CONCLUSION: The present study indicated that particles of 0.5 to 2 mm3 in size should be preferred to particles of 10 mm3 in size for bone grafting.