Influence of an allogenic collagen scaffold on implant sites with thin supracrestal tissue height: a randomized clinical trial.

OBJECTIVES: This randomized clinical trial focused on patients with thin peri-implant soft-tissue height (STH) (≤ 2.5 mm) and investigated the impact of an allogenic collagen scaffold (aCS) on supracrestal tissue height and marginal bone loss (MBL). MATERIAL & METHODS: Forty patients received bone level implants and were randomly assigned to the test group with simultaneous tissue thickening with aCS or the control group. After three months, prosthetic restoration occurred. STH measurements were taken at baseline (T0) and reopening surgery (TR), with MBL assessed at 12 months (T1). Descriptive statistics were calculated for continuous variables, and counts for categorical variables (significance level, p = 0.05). RESULTS: At T1, 37 patients were available. At T0, control and test groups had mean STH values of 2.3 ± 0.3 mm and 2.1 ± 0.4 mm. TR revealed mean STH values of 2.3 ± 0.2 mm (control) and 2.6 ± 0.7 mm (test), with a significant tissue thickening of 0.5 ± 0.6 mm in the test group (p < 0.03). At T1, control and test groups showed MBL mean values of 1.1 ± 0.8 mm and 1.0 ± 0.6 mm, with a moderate but significant correlation with STH thickening (-0.34), implant position (0.43), history of periodontitis (0.39), and smoking status (0.27). CONCLUSION: The use of an aCS protocol resulted in soft tissue thickening but did not reach a threshold to reliably reduce MBL compared to the control group within the study's limitations. CLINICAL RELEVANCE: Peri-implant STH is crucial for maintaining peri-implant marginal bone stability. Marginal bone stability represents a crucial factor in prevention of peri-implantitis development. German register of clinical trial registration number DRKS00033290.

Bone defect development in experimental canine peri-implantitis models: a systematic review.

PURPOSE: To provide a systematic overview of preclinical research regarding bone defect formation around different implant surfaces after ligature-induced peri-implantitis models in dogs. Two focused questions were formulated: 'How much bone loss can be expected after a certain time of ligature induced peri-implantitis?' and 'Do different implant types, dog breeds and study protocols differ in their extent of bone loss?' MATERIALS AND METHODS: A systematic literature search was conducted on four databases (MEDLINE, Web of Science, EMBASE and Scopus). Observations, which consisted of bone defects measured directly after ligature removal in canine models, were included and analysed. Two approaches were used to analyse the relatively heterogeneous studies that fulfilled the inclusion criteria. First, separate simple linear regressions were calculated for each study and implant surface, for which observations were available across multiple time points. Second, a linear mixed model was specified for the observations at 12 weeks after ligature initiation, and assessing the potential influencing factors on defect depth was explored using lasso regularisation. RESULTS: Thirty-six studies with a total of 1082 implants were included after. Bone loss was determined at different time points, either with clinical measurements radiographically or histologically. Different implant groups [e.g. turned, sand-blasted-acid-etched (SLA), titanium-plasma-sprayed (TPS) and other rough surfaces] were assessed and described in the studies. A mean incremental defect depth increase of 0.08 mm (SD: -0.01-0.28 mm) per week was observed. After 12 weeks, the defect depths ranged between 0.7 and 5 mm. Based on the current data set, implant surface could not be statistically identified as an essential factor in defect depth after 12 weeks of ligature-induced peri-implantitis. CONCLUSION: Expectable defect depth after a specific time of ligature-induced peri-implantitis can vary robustly. It is currently impossible to delineate apparent differences in bone loss around different implant surfaces.