Maxillary and mandibular overdentures retained by two unsplinted narrow-diameter titanium-zirconium implants - A clinical pilot study.

OBJECTIVES: To evaluate the survival rates and marginal bone loss of narrow-diameter titanium-zirconium implants supporting complete maxillary and mandibular overdentures up to 3 years after loading. MATERIALS AND METHODS: Ten completely edentulous patients who were dissatisfied with their complete dentures were enrolled. Two narrow-diameter implants were placed in the canine region of the maxilla and mandible. After second-stage surgery, implant-supported overdentures (palatal-free) attached by parallel alignable stud-attachments were placed. Patients were followed periodically for up to 36 months. Standardized radiographs were taken at baseline, 12 and 36 months to analyze mean marginal bone level changes around the implants. RESULTS: The Kaplan-Meier survival rates were 100% for mandibular and 68.0% (SE ± 10.9%) for maxillary implants at 36 months (p = .008). Six maxillary implants failed after loading; no mandibular implants were lost. Five implants failed due to loss of osseointegration. One implant fractured. The mean marginal bone level changes around the analyzed implants (n = 28, 9 patients) were -0.71 ± 0.82 mm in the mandible and -2.08 ± 1.52 mm in the maxilla at the 36-month follow-up. The difference in marginal bone level changes between the maxilla and mandible was significant (p = .019) at the 12- and 36-month follow-ups. CONCLUSION: Two narrow-diameter titanium-zirconium implants with stud-attachments showed a highly satisfactory outcome in the mandible. The maxillary implants showed a high failure rate and significantly more bone loss over time than the mandibular implants. The minimal concept of two implants and an overdenture should be limited to the edentulous mandible.

Early and mature biofilm on four different dental implant materials: An in vivo human study.

OBJECTIVES: The aim of this study was to examine the microbial composition of early (after 3 days, D3) and mature biofilms (after 31 days, D31) on materials typically used in implant/abutment buildups. Implant/abutment materials with different surface roughness values (Ra ) were compared to detect differences in the quantity and quality of bacterial composition. MATERIAL AND METHODS: Four different materials were investigated: rough implant surface (sand-blasted acid-etched titanium, Ti-p), implant collar (machined titanium, Ti-m), titanium abutment (Ti6Al4V), and zirconium dioxide abutment (ZrO2 ). Fourteen periodontally healthy subjects received mandibular acrylic devices with four disks (one for each material) facing the anterior lingual area. The total bacterial count was analyzed using RT-qPCR. Both presence and proliferation of 20 selected bacterial species were assessed with microarrays. RESULTS: The highest mean total cell counts (x108  ± standard deviation) were detected at D3 on ZrO2 (5.63 ± 4.83; Ra  = 0.74 µm), followed by Ti-p (4.53 ± 5.00; Ra  = 1.87), Ti-m (4.43 ± 9.38; Ra  = 0.18 µm), and Ti6Al4V (3.83 ± 3.13; Ra  = 0.16 µm). ZrO2 showed significantly higher total bacterial cell counts than Ti-p and Ti-m (p < .05) for both time intervals. The microarrays detected 16 (D3) and 17 (D31) bacterial species; those associated with healthy oral microbiotas, but also bacteria of the red complex (Tannerella forsythia, Treponema denticola), were found on all materials. CONCLUSIONS: Biofilms on ZrO2 harbored a higher total number of bacterial cells compared with those formed on titanium surfaces with much lower roughness values. Putative periodontopathogens were detected on all materials after both time intervals. Implant/abutment materials with a low surface roughness showed less biofilm accumulation.

Telescopic Crowns On Implants And Teeth: Evaluation Of A Clinical Study After 8 to 12 Years.

PURPOSE: To evaluate the outcome of a clinical study on telescopic-crown-retained removable dental prostheses (TCR-RDPs) on implants or implants and teeth after 8 to 12 years. MATERIALS AND METHODS: Between 1999 and 2002, 39 (41 jaws) patients received implant- or combined tooth-implant-supported TCR-RDPs in the maxilla and/or mandible. One-stage surgery was performed, and after a conventional healing period, TCR-RDPs were inserted. Thirty-one patients (33 prostheses) were available for annual follow-up investigations with a standardized protocol from 2010 until 2013. Cumulative survival and success of the abutments was estimated using the Kaplan-Meier method, and a Cox regression model was used to identify potential predictors for abutment complications. Patients' oral health-related quality of life (OHRQoL) was measured by means of the Oral Health Impact Profile (OHIP). RESULTS: After a mean observation period of 11.3 ± 1.1 years, all restorations were still functioning successfully. Two implants and 10 abutment teeth were lost, leading to significantly different implant and tooth survival rates of 97.6% (SE ± 1.7%) and 81.8% (SE 5.3%; P = .007). Implants placed in the mandible, and those in the group with a higher number of abutments (5 to 6 vs 2 to 4) showed higher success rates. The success rates of abutment teeth were not influenced by location (mandible vs maxilla) or number of abutments (5 to 6 vs 2 to 4). CONCLUSION: Implant- or combined tooth-implant-supported TCR-RDPs provided a satisfying treatment option for patients with severely reduced dentition in the long term. Due to the small sample size, the results presented should be interpreted with caution.

Assessment of cortical bone thickness using ultrasound.

PURPOSE: The aim of the study was to analyze the accuracy of measuring the cortical bone thickness using a combination of low- and high-frequency ultrasound (US) compared with cone-beam computed tomography (CBCT) and using stereomicroscopy as reference method. MATERIAL AND METHODS: Ten jawbone models were prepared using bovine ribs and porcine gingiva. A dental implant was placed in each model. All models were investigated by US, CBCT, and stereomicroscopy. The cortical bone thickness was measured directly above and 4 mm beside the implant with each method in different slices. RESULTS: The median deviation of US measurements compared to the reference method was 0.23 mm. The CBCT method was slightly more accurate (median percent deviation of 9.2%) than the US method (10.3%). However, US measurements directly above the implant were more accurate than CBCT measurements with a median percent deviation of 10.5% for US vs. 11.8% for CBCT. CONCLUSION: Ultrasound showed a high potential to supplement CBCT for measurements of the cortical bone thickness.

The randomized shortened dental arch study: influence of two different treatments on interdental spacing over 5 years.

OBJECTIVES: Being a secondary outcome in a multicenter randomized controlled trial, the present analysis focused on interdental spacing in the shortened dental arch (SDA). The aim was to evaluate changes in interdental spacing in dependence of two different treatments after an observation period of up to 5 years. MATERIAL AND METHODS: Patients were either treated with a partial removable dental prosthesis (PRDP) for molar replacement (PRDP group) or according to the SDA concept aiming at a premolar occlusion (SDA group) in a randomized manner. Interdental spacing in the anterior region was measured with gauges and categorized as "0" (<0.1 mm), "1" (<0.5 mm), "2" (0.5-1 mm), and "3" (>1 mm). The statistical analysis was performed with analysis of variance models followed by linear contrast. RESULTS: Ninety-one patients (SDA n = 41, PRDP n = 50) were included. Changes of interdental spacing were detected in 70.7 % of all cases. A significant difference between the mean score changes was found in the mandible comparing the PRDP group and the SDA group. The respective mean score changes from baseline to 5 years were 0.23 (SD 0.49) for the PRDP group and 0.02 (SD 0.30) for the SDA group (p = 0.023). CONCLUSIONS: Major interdental spacing could be observed in neither of the groups. The SDA concept resulted in a slightly better outcome. CLINICAL RELEVANCE: When deciding whether to replace missing molars, the present results give further support to the SDA concept.

Loading protocols and implant supported restorations proposed for the rehabilitation of partially and fully edentulous jaws. Camlog Foundation Consensus Report.

OBJECTIVES: The aim of this consensus meeting was to assess whether immediate loading protocols achieve comparable clinical outcomes when compared to conventional loading protocols depending on the type of prosthetic restoration. In addition post-loading implant loss for implant supported prostheses in edentulous jaws was analyzed regarding a potential impact of implant location (maxilla vs. mandible), implant number per patient, type of prosthesis (removable vs. fixed), and type of attachment system (screw-retained, ball vs. bar vs. telescopic crown). MATERIAL AND METHODS: Two comprehensive systematic reviews were prepared in advance of the meeting. Consensus statements, practical recommendations, and implications for future research were based on within group as well as plenary scrutinization and discussions of these systematic reviews. RESULTS: The survival rates are high for immediate loaded and conventional loaded implants, but immediate loading may impose a greater risk for implant failure. The estimated implant loss rate is influenced by the implant location, type of restoration, and implant number. CONCLUSIONS: Consistent reporting of clinical studies is necessary and high-quality studies are needed to confirm the present results.

A systematic review and meta-analysis of removable and fixed implant-supported prostheses in edentulous jaws: post-loading implant loss.

OBJECTIVES: The aim of this systematic review was to analyze post-loading implant loss for implant-supported prostheses in edentulous jaws, regarding a potential impact of implant location (maxilla vs. mandible), implant number per patient, type of prosthesis (removable vs. fixed), and type of attachment system (screw-retained, ball vs. bar vs. telescopic crown). MATERIAL AND METHODS: A systematic literature search for randomized-controlled trials (RCTs) or prospective studies was conducted within PubMed, Cochrane Library, and Embase. Quality assessment of the included studies was carried out, and the review was structured according to PRISMA. Implant loss and corresponding 3- and 5-year survival rates were estimated by means of a Poisson regression model with total exposure time as offset. RESULTS: After title, abstract, and full-text screening, 54 studies were included for qualitative analyses. Estimated 5-year survival rates of implants were 97.9% [95% CI 97.4; 98.4] in the maxilla and 98.9% [95% CI 98.7; 99.1] in the mandible. Corresponding implant loss rates per 100 implant years were significantly higher in the maxilla (0.42 [95% CI 0.33; 0.53] vs. 0.22 [95% CI 0.17; 0.27]; P = 0.0001). Implant loss rates for fixed restorations were significantly lower compared to removable restorations (0.23 [95% CI 0.18; 0.29] vs. 0.35 [95% CI 0.28; 0.44]; P = 0.0148). Four implants and a fixed restoration in the mandible resulted in significantly higher implant loss rates compared to five or more implants with a fixed restoration. The analysis of one implant and a mandibular overdenture also revealed higher implant loss rates than an overdenture on two implants. The same (lower implant number = higher implant loss rate) applied when comparing 2 vs. 4 implants and a mandibular overdenture. Implant loss rates for maxillary overdentures on <4 implants were significantly higher than for four implants (7.22 [95% CI 5.41; 9.64] vs. 2.31 [1.56; 3.42]; P < 0.0001). CONCLUSIONS: Implant location, type of restoration, and implant number do have an influence on the estimated implant loss rate. Consistent reporting of clinical studies is necessary and high-quality studies are needed to confirm the present results.