A Randomized Controlled Trial Comparing Collagen Matrix to Hemostatic Gelatin Sponge as Socket Seal in Alveolar Ridge Preservation

(1) Objectives: This study aimed to compare a collagen matrix to a hemostatic gelatin sponge as a socket seal in alveolar ridge preservation (ARP). (2) Methods: Systemically healthy patients planned for ARP at two sites with more than 50% of the buccal bone wall remaining after tooth extraction were eligible for inclusion. ARP involved socket grafting using collagen-enriched deproteinized bovine bone mineral. Sites were then randomly assigned to the test group (collagen matrix) or the control group (hemostatic gelatin sponge). The primary outcome was soft tissue thickness in the center of the site at 4 months, analyzed on cone-beam computed tomography. Secondary outcomes included the buccal and lingual soft tissue heights, horizontal bone loss, buccal soft tissue profile changes, wound dimensions, and Socket Wound Healing Score (SWHS). (3) Results: In total, 18 patients (12 females, 6 males) with a mean age of 57.3 years (SD 11.1) were included. Four months after ARP, the soft tissue thickness in the center of the site amounted to 2.48 mm (SD 0.70) in the test group and 1.81 mm (SD 0.69) in the control group. The difference of 0.67 mm (95% CI: 0.20-1.14) in favor of the collagen matrix was statistically significant (p < 0.009). The buccal soft tissue height was also statistically significantly higher for the collagen matrix (0.72 mm; 95% CI: 0.06-1.38; p = 0.034). A trend favoring the collagen matrix was found for the lingual soft tissue height (p = 0.066). No significant differences between the groups in terms of horizontal bone loss, buccal soft tissue profile changes, wound dimensions, and the SWHS were found. (4) Conclusions: The absence of significant differences in hard tissue outcomes suggests that both the collagen matrix and hemostatic gelatin sponge effectively sealed the extraction socket and supported bone preservation. However, the collagen matrix better maintained soft tissue dimensions. The clinical relevance of this finding with respect to the necessity for adjunctive soft tissue augmentation at the time of implant placement is yet to be studied.

Immediate implant placement with flap or flapless surgery: A systematic review and meta-analysis

AIM

To assess the impact of mucoperiosteal flap elevation for single immediate implant placement (IIP) on buccal hard and soft tissue changes, and on clinical, aesthetic and patient-reported outcomes.

MATERIALS AND METHODS

Two independent reviewers conducted an electronic literature search in Pubmed, Web of Science, Embase and Cochrane databases as well as a manual search to identify eligible clinical studies up to June 2022. Randomized controlled trials (RCTs) comparing IIP without flap elevation to IIP with flap elevation were included for a qualitative and quantitative analysis. The primary outcome was horizontal buccal bone change. Secondary outcomes were implant survival, vertical buccal bone change, pain, and clinical and aesthetic parameters.

RESULTS

Out of 1029 records, 5 RCTs were selected reporting on 140 patients who received 140 single immediate implants (flapless: 68; flap: 72). Patients had a mean age ranging from 30 to 67 years and were followed between 6 and 12 months. Four RCTs pertained to (nearly) intact alveoli. Risk of bias assessment yielded low risk for two RCTs and high risk for three RCTs. Meta-analysis demonstrated a mean difference of 0.48 mm (95% confidence interval [CI] [0.13, 0.84], p = .007) in horizontal buccal bone change between surgical approaches, favouring flapless surgery. Meta-analysis failed to demonstrate a significant difference in implant survival between the groups (RR 1.00, 95% CI [0.93, 1.07], p = .920). Given the scarcity of data, meta-analyses could not be performed on other secondary outcomes. Available studies were consistent in the direction of the effect favouring flapless surgery for vertical buccal bone change as well as for pain. Clinical and aesthetic parameters were underreported.

CONCLUSIONS

Based on CBCT data, flapless surgery resulted in more buccal bone preservation at immediate implants. However, the clinical relevance of this finding is unclear, since clinical and aesthetic outcomes were underreported.

A Split-Mouth Study to Assess the Effect of Implant Surface Roughness on Implant Treatment Outcome After 5 Years

The aim of current split-mouth study was to compare the implant treatment outcomes of hybrid-surface implants (minimally rough implant collar and moderately rough body) with moderately rough implants after 5 years in patients with a bar-supported mandibular overdenture. Fully edentulous patients were enrolled, and each patient received two implants: one moderately rough and one hybrid-surface implant. A total of 18 patients with 36 implants attended the 5-year recall, and the implant survival rate was 100%. The 5-year evaluation showed no significant difference in crestal bone loss or peri-implant health between the hybrid and moderately rough implants.

Screw loosening in angulation-correcting single implant restorations: A systematic review of in vitro studies

STATEMENT OF PROBLEM

Various options are available to allow angle correction for screw-retained restorations for malaligned implants, including angled abutments, angled screw channel abutments, and angled implants. However, the effect these angle correction components have on prosthetic screw loosening is unclear.

PURPOSE

The purpose of this systematic review was to assess the effect of angled abutments, angled screw channel abutments, and angled implants on prosthetic screw loosening.

MATERIAL AND METHODS

This manuscript followed the Preferred Reporting Items for the Systematic Review and Meta-Analyses (PRISMA) statement. Searches were performed through 31 December 2021 in PubMed/MEDLINE, EMBASE, and Web of Science with no year limit targeting in vitro studies evaluating the effect of angulation correction components on screw loosening.

RESULTS

A total of 460 articles were identified. After removing duplicates, 306 titles were screened. Nine of the remaining 36 articles selected for full-text analysis met the selection criteria. The qualitative analysis used data from 394 implants. All studies featured straight abutments as the control group, and, in 8 studies, the angle correction component was included on the level of the abutment. Only in 1 study was the angle correction component at the level of the implant. The angle correction of the prosthetic component varied from 0 degrees in all studies up to a maximum correction of 30 degrees. Statistically significant increases in screw loosening with increasing abutment angle correction were reported by multiple authors (P<.05). However, other articles reported nonsignificant differences in screw loosening because of angulation after cyclic loading (P>.05). The only study investigating angle correction at the implant level found significantly less screw loosening (P<.05) in the angled implant group compared with the nonangled implant group.

CONCLUSIONS

Several options are available to correct discrepancies between the surgical axis and the ideal prosthetic axis for rehabilitations supported by dental implants. The current evidence does not clearly indicate the superiority of any single solution for minimizing screw loosening.

Four-implant-supported overdenture treatment in the maxilla. Part I: A randomized controlled split mouth trial assessing the effect of microthreads and abutment connection type on 4 years peri-implant health

BACKGROUND

According to literature, peri-implant bone loss is minimized on implants with microthreaded neck design and internal type of abutment connection. However, most clinical studies may be biased due to confounding factors.

PURPOSE

This nonblinded RCT assessed the effect of implant neck (microthreaded vs non-microthreaded) as well as the type of abutment connection (internal conical vs external flat-to-flat) on peri-implant bone stability and peri-implant health after at least 36 months.

MATERIALS AND METHODS

Twenty-five patients were treated with a maxillary implant-supported bar-retained overdenture on four different implant types: internal connection with microthreads (I-MT), internal connection without microthreads (I-NMT), external connection with microthreads (E-MT), and external connection without microthreads (E-NMT). To control confounding factors, all other design features were similar. A linear mixed-model analysis or mixed-model logistic regression analysis was used to determine the effect of implant type on bone level, probing pocket depth, bleeding on probing, and plaque.

RESULTS

Four out of 98 implants (4.1%) placed in 25 patients failed during provisionalization and were replaced. Mean overall bone loss after 6 months was 0.39 mm (SD 0.62, range 0.00-3.48) with limited additional bone loss of 0.04 mm (SD 0.54, range -1.80-1.63) after at least 3 years. Microthreads or connection type had no effect on the bone level, probing pocket depth, bleeding on probing, nor plaque.

CONCLUSIONS

With 96% of implant survival, the maxillary overdenture supported with a bar on four implants yield a predictable outcome and the implant-abutment connection type (internal vs external) and implant neck design (microthreaded vs non-microthreaded) have no influence on peri-implant bone remodeling after initial bone remodeling nor up to 4 years of function. Peri-implant bone levels are within international success standards and peri-implant health is indicative of absence of peri-implantitis.

Rationale for a reverse tapered body shift implant for immediate placement

Immediate implant placement holds considerable value, yet primary implant stability is often a critical factor. The aim of this study was to evaluate the stability, volumetric viability, and buccal gap size of reverse tapered body shift (RTBS) implants after immediate placement. Peak insertion torque measurements of two RTBS designs (apical 40% vs. apical 50%), relative to conventionally tapered implants, were assessed in simulated extraction sockets prepared in synthetic bone blocks. Additionally, the proximity of the RTBS implants to neighbouring teeth and anatomical structures, and the buccal gap distance were evaluated in human cadavers. The mean (± standard deviation) insertion torque was 12.00±1.40N•cm for the conventionally tapered implants (n=50), 35.36±2.74N•cm (n=50) for RTBS-1, and 48.20±2.90N•cm (n=50) for RTBS-2; the difference between designs was statistically significant (P<0.01). In total, 40 RTBS implants (20 per design) were placed in six cadaveric premaxillae. Only one locus was inappropriate for both RTBS implant designs, due to the proximity of neighbouring teeth. The average buccal gap for both implant designs was 2.8mm (P=0.104). The improved primary stability and increased buccal gap size with RTBS implants may enhance the feasibility of immediate placement. The study findings should be further validated in clinical trials.

Cost-effectiveness analysis of two attachment systems for mandibular overdenture

Objectives

This study analysed the cost‐effectiveness of two different attachments for the 2‐implant overdenture (2IOD) in edentulous mandibles.

Materials and methods

When considering alternative treatments, cost‐effectiveness analysis is an important factor for stakeholders (patient, clinician, social security, insurance company, etc.). A general practice population (n = 116) was treated between 2003 and 2013 with a mandibular 2IOD with 2 different ball/stud attachment systems, one spherical (Group D) and one cylindrical (Group L). Patient well‐being was assessed with OHIP‐14‐Total (OHIP‐14‐T), at intake and annually up to 5 years, to calculate the health effect. Initial and maintenance costs of both treatments were inventoried. The cost‐effectiveness was compared. Annual discount rates of 4% and 1.5% were applied to future costs and health outcomes, following Dutch guidelines. Prices were adjusted to the year 2003. To offset the uncertainty in relevant input parameters, a sensitivity analysis was performed using bootstrap analysis. Significance was set at p < .05.

Results

The health effect was 6.36 (SD 5.32) for Group D and 8.54 (SD 5.63) for Group L. The sum of the discounted costs up to 5 years was EUR 4,210.98 (SD 634.75) for the D and EUR 3,840.62 (SD 302.63) for the Group L (p = .005). The bootstrapping reports that L abutment clearly dominates the D abutment in terms of cost‐effectiveness.

Conclusions

The 2IOD on the L abutment is dominant compared to the 2IOD on D abutment, in a 5‐year perspective.

Improvement of Quality of Life with Implant-Supported Mandibular Overdentures and the Effect of Implant Type and Surgical Procedure on Bone and Soft Tissue Stability: A Three-Year Prospective Split-Mouth Trial

In fully edentulous patients, the support of a lower dental prosthesis by two implants could improve the chewing ability, retention, and stability of the prosthesis. Despite high success rates of dental implants, complications, such as peri-implantitis, do occur. The latter is a consequence of crestal bone loss and might be related to the implant surface and peri-implant soft tissue thickness. The aim of this paper is to describe the effect of implant surface roughness and soft tissue thickness on crestal bone remodeling, peri-implant health, and patient-centered outcomes. The mandibular overdenture supported by two implants is used as a split-mouth model to scrutinize these aims. The first study compared implants placed equicrestal to implants placed biologically (i.e., dependent on site-specific soft tissue thickness). The second clinical trial compared implants with a minimally to a moderately rough implant neck. Both studies reported an improvement in oral health-related quality of life and a stable peri-implant health after three years follow-up. Only equicrestal implant placement yielded significantly higher implant surface exposure, due to the establishment of the biologic width. Within the limitations of this study, it can be concluded that an implant supported mandibular overdenture significantly improves the quality of life, with limited biologic complications and high survival rates of the implants.

The Influence of Initial Hard and Soft Tissue Dimensions on Initial Crestal Bone Loss of Immediately Loaded Dental Implants

The aim of this case-control study was to evaluate the influence of soft tissue thickness at implant placement (thin [< 3 mm] vs thick [≥ 3 mm]) and bone volume (abundant vs limited) on initial crestal bone remodeling of immediate postextraction and delayed (healed site) implants in immediate loading situations. A total of 67 patients with 133 implants could be evaluated, of which 77 were placed immediately after extraction and 56 in healed ridges. If sufficient bone volume is present and primary stability is achieved, immediate loading of the implant yields good clinical and radiographic outcomes, yet implants placed in healed ridges with thin soft tissues are more prone to initial crestal bone loss.

Peri-implant health, clinical outcome and patient-centred outcomes of implant-supported overdentures in the mandible and the maxilla

Objectives/Aims:

The primary aim of this retrospective pilot study was to evaluate the clinical outcome of overdentures on four non-splinted maxillary implants compared to the mandible using locator attachments and secondly to assess patient's opinion of the treatment.

Materials and Methods:

The treatment protocol used here is summarised as a single-stage surgical approach followed by immediate loading (same day in 12 of 17 patients) of a removable prosthesis in the maxilla and mandible. Most of the implants were installed into fresh extraction sockets. Clinical outcomes were evaluated in 68 southern implants, straight (non co-axis) or angulated (co-axis) in 17 patients. Patients were examined by independent examiners at an average follow-up of 14.5 months after implant placement.

Results:

Outcomes measured were implant survival, bone loss, bleeding on probing, probing pocket depths and plaque score in addition to quality of life measured with OHIP-14 questionnaires. An overall implant survival of 100% was achieved. The mean marginal bone level (mm) over the entire cohort of 66 measured implants was (1.4 mm; range, 0–5.5). A significant difference (P=0.01) was found between bone level, from implant head to bone contact in the maxilla (M, 0.9 mm; s.d., 1.1; range, 0–4) and the mandible (M, 1.7; s.d., 1.0; range, 0–5.5). The marginal bone-to-implant head distance with the angulated co-axis implants was 1.9 mm (s.d., 1.5; range, 0–5.5) compared to non co-axis, mean 1.2 mm (s.d., 1.1; range, 0–4) (P=0.01). The OHIP-14 overall mean was 3.3 (out of a maximum of 56).

Conclusion:

The implant survival was 100% and the patients benefited from the overdenture treatment on four non-connected implants. The extremely low OHIP-14 indicated a very high level of patient satisfaction following treatment. The results of this study merit further long-term investigation to fully investigate the success of immediately loading implants in the maxilla as well as cost-benefit.