Randomized controlled clinical study comparing two types of two-piece dental implants supporting fixed restorations-Results at 8 years of loading.

OBJECTIVES: To assess clinical, technical, biological, and radiographic outcomes of implants supporting fixed restorations using two types of dental implants with non-matching implant-abutment junctions at 8 years. MATERIALS AND METHODS: Sixty-four patients were randomly assigned to receive one of two implant systems (S1 or S2) and eventually fixed restorations. Patients were examined at loading (TL ), one (T1 ), three (T3 ), five (T5 ), and eight years (T8 ). Outcome measures included implant and restoration survival, technical and biological complications, and radiographic bone levels. All data were analyzed on the implant and patient level. RESULTS: Ninety-eight implants were inserted in 64 patients and loaded with fixed restorations. At 8 years, 49 patients with 42 (S1) and 36 (S2) implants (25 in group S1 and 24 in group S2 on the patient level) were re-examined. The survival rates on the patient level were 97.6% (S1) and 97.2% (S2). The marginal bone levels (the primary endpoint) amounted to a gain of 0.21 mm (Q1: -0.11 mm; Q3: 0.5 mm) (S1) (p = .007) and to a loss of 0.24 mm (Q1: -0.79 mm; Q3: 0.05 mm) (S2) (p = .001) between baseline (TL ) and T8 (intergroup p < .001). The technical complication rates were 28% (S1) and 12.5% (S2) (intergroup p = .289). Peri-implant mucositis was observed in 24% (S1) and 50% (S2) of the implants on the patient level (intergroup p = .792). The respective figures for peri-implantitis were 0% (S1) and 12.5% (S2) (intergroup p = .11). CONCLUSIONS: Dental implants with non-matching implant-abutment junctions supporting fixed restorations resulted in high survival rates independent of the system used. Differences, mainly observed in terms of technical complications (in favor of S2), biological complications (in favor of S1), and marginal bone-level changes (in favor of group S1), appear to be clinically negligible.

Augmentation of soft tissue volume at pontic sites: a comparison between a cross-linked and a non-cross-linked collagen matrix.

AIM: To assess histopathological and histomorphometric outcomes of soft tissue volume augmentation procedures at pontic sites using a volume-stable cross-linked collagen matrix (VCMX) and a non-cross-linked collagen matrix (XCM). MATERIALS AND METHODS: In twelve adult beagle dogs, the mandibular premolars and first molar were hemisected and the mesial root extracted. Soft tissue augmentation was randomly performed using VCMX, XCM, or a sham-operated control. Sacrifice was performed after 4, 8, and 26 weeks. Non-decalcified sections were analyzed for histopathologic and histomorphometric measurements at four different levels below the crest (1.5, 2.5, 3.5, and 5.5 mm). RESULTS: Group VCMX presented a greater overall amount of soft tissue at all healing time points, more pronounced fibroblast ingrowth, vascularization, and a substantial new collagen deposition. Over time, group XCM demonstrated faster signs of degradation compared with group VCMX. Four weeks after augmentation, group VCMX yielded a higher mean ridge width compared with groups XCM (2.22 mm VCMX, 0.89 mm XCM (at 2.5 mm); 2.05 mm VCMX, 0.80 mm XCM (at 3.5 mm) p < 0.05) and sham (0.59 mm sham (at 1.5 mm); 0.48 mm (at 2.5 mm); 0.44 mm (at 3.5 mm) p < 0.05). After healing periods of 8 and 26 weeks, measurements in group VCMX remained significantly higher compared with group sham both at 8 weeks (levels of 1.5 mm, 2.5 mm and 5.5 mm) and at 26 weeks (levels of 1.5 mm, 3.5 mm and 5.5 mm) (p < 0.05). CONCLUSION: The use of a cross-linked collagen matrix resulted in a greater and more stable ridge width over time compared with control groups. CLINICAL RELEVANCE: Soft tissue volume augmentation at pontic sites is more effective when using a cross-linked compared with a non-cross-linked collagen matrix.