Efficacy of a collagen matrix for soft tissue augmentation after implant placement compared to connective tissue grafts: A multicenter, noninferiority, randomized controlled trial.

OBJECTIVES: To test whether soft tissue volume augmentation using a collagen matrix (VCMX) leads to noninferior results in terms of gain of mucosal thickness at single implant sites, compared to connective tissue grafts (SCTG). METHODS: The study was designed as a multi-center randomized controlled clinical trial. Subjects in need of soft tissue volume augmentation at single tooth implant sites were consecutively recruited at nine centers. The deficient mucosal thickness at the implant sites (one per patient) was augmented by applying either a VCMX or a SCTG. Patients were examined at 120 days (abutment connection = primary endpoint), 180 days (final restoration), and 360 days (1-year after insertion of the final restoration). Outcome measures included: transmucosal probing of the mucosal thickness (crestal = primary outcome), profilometric measurements of the tissue volume, and patient-reported outcome measures (PROMs). RESULTS: Out of the 88 patients, 79 attended the one-year follow-up. The median increase of the crestal mucosal thickness between pre-augmentation and 120 days was 0.3 ± 2.1 mm in the VCMX group and 0.8 ± 1.6 mm in the SCTG group (p = .455). Non-inferiority of the VCMX compared to the SCTG was not observed. The respective numbers at the buccal aspect amounted to 0.9 ± 2.0 mm (VCMX) and 1.1 ± 1.4 mm (SCTG; p = .431). PROMs including pain perception favored the VCMX group. CONCLUSION: It remains inconclusive whether soft tissue augmentation using a VCMX is noninferior to SCTG in terms of crestal mucosal thickening at single implant sites. However, the use of collagen matrices favors PROMs especially pain perception, while achieving similar buccal volume gains along with comparable clinical and aesthetic parameters to SCTG.

Implant-supported overdentures with different clinical configurations: Mechanical resistance using a numerical approach.

STATEMENT OF PROBLEM: Implant-supported overdentures (IODs) are a treatment option for patients with complete edentulism. However, this treatment increases the possibilities of peri-implant complications, characterized by inflammation or partial loss of surrounding hard and soft tissues. PURPOSE: The purpose of this finite element analysis study was to evaluate the mechanical performance of different bar-IOD designs under different clinical configurations by comparing the stress and strain distribution on the bone during secondary stabilization. MATERIAL AND METHODS: A finite element model of the mandible representing a patient with complete edentulism was developed. Different designs of bar-IODs were modeled and compared. The parameters studied were the material properties (cobalt-chromium, zirconium dioxide, titanium grade 5, and titanium grade 4), diameter and bar-IOD cross-sectional shape, tilt of the posterior implants (30 degrees), presence of a distal extension cantilever in the bar-IODs (12 mm), and number of implants (4 or 6). Two different mastication loading conditions were analyzed. One- and 2-way ANOVAs and the Tukey honestly significant differences post hoc test (α=.05) were used to determine the significant von Mises stress and strain values in the bone. RESULTS: The 4 materials tested in the bar-IOD did not have a significant mechanical effect on the bone (P<.05). A smaller diameter and structure of the bar-IOD led to significantly higher bone stress (P<.001). A distal extension cantilever led to an increased stress concentration (model M1 versus model M3: P<.001), which reached 50% in the event of tilting of the posterior implants (model M2 versus model M4: P<.001). Tilting of the posterior implants alone, without extension, had a nonsignificant effect (model M3 versus model M4: P=.999). Model M5 supported with 6 implants reduces the stress transferred to the bone compared with model M3 supported with 4 implants (P<.05). CONCLUSIONS: Distal extensions in bar-IODs, the tilt of the posterior implants, and the low amount of material in the cross-sectional area in the bar-IOD were the most influential parameters on the mechanical resistance of dental implants in the mandibular bone.

Mechanical strength and fracture point of a dental implant under certification conditions: A numerical approach by finite element analysis.

STATEMENT OF PROBLEM: Implant prosthodontics provides high-quality outcomes thanks to recent technological developments and certification procedures such as International Organization for Standardization (ISO) 14801. However, these certification tests are costly, and the result is highly uncertain as the influence of design variables (materials and structure) is still unknown. The design process could be significantly improved if the influence of design parameters were identified. PURPOSE: The purpose of this in vitro study was to use finite element analysis (FEA) to assess the influence of design parameters on the mechanical performance of an implant in regard to testing conditions of ISO 14801 standard. MATERIAL AND METHODS: An endosseous dental implant was loaded under ISO 14801 testing conditions by numerical simulation, with 4 parameters evaluated under the following conditions: conditions of the contact surface area between the implant and the loading tool, length of the fixation screw, implant embedding depth, and material used for implant stiffness. FEA was used to compare the force that needed to reach the implant's yield and fracture strength. RESULTS: A dental implant's fracture point can be increased by 41% by improving the contact surface area, by 20% depending on the type of material, by 4% depending on the length of the fixation screw, and by 1.4% by changing the implant embedding depth. CONCLUSIONS: FEA made it possible to evaluate 4 performance parameters of a dental implant under ISO 14801 conditions. Under these conditions, the contact surface area was found to be the major parameter influencing implant performance. This observation was validated experimentally in a fatigue test under ISO 14801 conditions.

Esthetic evaluation of periimplant soft tissue of immediate single-implant placement and provisionalization in the anterior maxilla.

PURPOSE: To investigate periimplant soft tissue response following flapless extraction and immediate implant placement and provisionalization (IIPP) associated with bovine hydroxyapatite bone and connective tissue grafting in the anterior maxilla. The study evaluated the effectiveness of this technique in terms of soft tissue contours in esthetic areas with the use of the pink esthetic score (PES). MATERIALS AND METHODS: In this retrospective study, 39 consecutive patients were treated and followed by two experienced clinicians for single-tooth implant treatment in the esthetic zone. Treatment consisted of flapless extraction, immediate implant placement, inorganic bovine bone filling of the periimplant gap, and connective tissue grafting. A provisional crown was placed at the time of implant placement. The final crown was positioned 5 to 8 months after surgery. To assess the esthetic outcome of the technique, the soft tissue around the tooth to be extracted was scored according to the PES by seven evaluators before the surgery at visit 1 (v1), and at least 1 year after the final prosthesis placement at visit 2 (v2). RESULTS: After a mean follow-up of 4 years, the mean total PES score on a scale from 1 to 10 was 5.64 and 7.07 at v1 and v2, respectively. Statistical analysis revealed a significant difference between the PES scores before surgery and at the follow-up examination of the anterior single implants (P = 0.0008). CONCLUSION: Within the limitations of this study, postextraction with immediate implant loading associated with bovine hydroxyapatite and connective tissue grafting is a predictable technique. The esthetic outcome is that soft tissue seems to be maintained or improved significantly according to PES assessment compared with baseline.