The International Journal of Prosthodontics, 04/2019

Purpose: To retrospectively assess implant stability quotient (ISQ) values in patients who were followed up between 1998 and 2014 and to evaluate any correlations between ISQ and clinical parameters, such as change in marginal bone level (MBL). Materials and Methods: A total of 173 participants (65 men and 108 women; age range 21 to 85 years) and 383 implants were included. Implant location, MBL, and ISQ were recorded at surgery and at various recall times for statistical analysis. Mixed-model analysis was applied to evaluate the impact of clinical and demographic variables (time, implant location, patient gender) on ISQ and the correlation between ISQ and MBL. The level of significance was set at P .05. Results: Of the 21 failed implants, 20 failed within 1 year of functional loading, resulting in a 10-year cumulative implant survival estimate of 95%. The failed implants had lower ISQs at surgery (52.3 ± 7.03) and baseline (52.5 ± 4.20) when compared to surviving implants (63.0 ± 10.74 at surgery and 62.3 ± 8.30 at baseline), and the difference was statistically significant at surgery (P .05). The mean ISQs generally increased over time, but there were various patterns of changes between implants when grouped according to patient gender and implant location. There was no statistically significant correlation between the changes in ISQ and MBL (P = .211), despite an inverse relationship. Conclusion: Low initial ISQ values may help to identify implants at higher risk of failure. There may be various patterns of change over time in addition to an overall increase in ISQ values. Both similar and contradictory findings were found when compared to earlier literature, and a correlation between resonance frequency analysis and MBL change could not be identified. Despite limitations, the present study provides an overview of the clinical performance of RFA based on long-term clinical data.

Purpose: To investigate the relationship between oral health-related quality of life (OHRQoL) and usage period of complete dentures. Materials and Methods: Data were obtained from 432 edentulous patients who required complete dentures as part of an investigation registered in the University Hospital Medical Information Network (UMIN) Center (UMINCTR clinical trial, unique trial number: 000028711). Mandibular ridge form, denture quality, and usage period of the dentures were recorded and incorporated into a multiple linear regression analysis. Results: Multiple linear regression analysis in the 267 participants who completed the study demonstrated significant effects on OHRQoL of mandibular ridge form, mandibular denture stability and retention, accuracy of jaw relation recording, and usage period of dentures. Conclusion: A significant relationship between the usage period of dentures and OHRQoL in complete denture wearers was noted when the effects of mandibular ridge form and denture quality were controlled for.

Purpose: To assess the effectiveness of clinical decision support systems (CDSS) on the survival of natural teeth. Materials and Methods: The PubMed, ERIC, Google Scholar, and Medline databases were searched for full-text articles published between 2009 and 2018. Eight studies evaluating the use of CDSS for clinical decision-making were included in the systematic review. Results: CDSS were an effective technique for assisting clinicians in their daily practice. Conclusion: CDSS are effective and can be adopted in daily practice to assist clinicians in handling cases that require sound knowledge of the principles associated with the treatment.

Purpose: To increase awareness of subpontic osseous hyperplasia (SOH), an uncommon benign mass found underneath the pontics of fixed partial dentures (FPDs) and occasionally in implant-supported dental prostheses. Materials and Methods: A PubMed search in the English-language literature was conducted for case reports and case series of SOH. Demographic information gleaned from these publications included patient age and gender, lesion sites, outcomes, comorbidities, symptomatology, and periodontal involvement. To exemplify the findings of SOH, a clinical investigation of a 73-year-old affected woman has been detailed. Results/Conclusion: With the inclusion of this featured case, 71 patients with 80 affected sites were identified with SOH and served as the basis for the provided database. To date, this aggregation of cases represents the largest collection to undergo clinicopathologic review. SOHs appeared as dome-shaped radiopacities and tended to exhibit increased osteosclerosis with increased duration. The average age at discovery was 57 years, and SOH was found somewhat more often in women. Lesions were more likely to occur in the left posterior mandible. Affected patients may experience increased difficulty maintaining adequate oral hygiene, potentially leading to periodontal disease or discomfort. Overgrowths should be surgically removed when satisfactory oral hygiene measures have been compromised, when there are atypical clinical or radiographic presentations, or with incident symptomatology.

Purpose: To evaluate the vertical marginal (VM) and horizontal marginal (HM) misfit of frameworks made using different techniques. Materials and Methods: A total of 30 frameworks were divided into three groups of 10 samples each based on manufacturing technique: nichrome cast (G1), milled in zirconia (G2), and milled in wax and fused to metal (G3). Marginal misfit was measured using a three-dimensional optical microscope. Results: The highest VM misfit was in G3 (83.5 μm), followed by G1 (55 μm) and G2 (42 μm). The highest HM misfit was in G2 (118 μm), followed by G3 (102 μm) and G1 (−85 μm). Conclusion: Frameworks milled in zirconia resulted in the lowest VM misfit, while frameworks filled in wax and fused to metal resulted in higher VM. The HM misfit was favorable in the lost-wax technique.

Purpose: To compare the tightening torque accuracy of three electronic torque drivers. Materials and Methods: Three electronic torque drivers were assessed using two measurement methods-pure output torque (POT) and clinical output torque (COT). For both methods, assessments were performed at set torques of 10, 20, 30, and 40 Ncm, 10 times for each setting, with each driver tested. Appropriate statistical analysis was performed according to data distribution (ie, normal vs non-normal) (α = .05). Results: POT was significantly higher than COT at a set torque of 30 Ncm (P .001). Conclusion: In fastening an implant screw at 30 Ncm, the operator should also consider the output torque generated in the electronic torque driver.

Purpose: To examine and compare the trueness between a computer-aided design (CAD) file and the final milled prosthesis. Materials and Methods: For each included patient (n = 30), two lithium disilicate crowns were produced (n = 60) using two different CAD/computer-assisted manufacture (CAD/CAM) systems (allin- one type and combination type). To compare the trueness, the scanned internal surfaces of the fabricated prostheses were compared to the design files in CAD using 3D analysis software (Geomagic Control X, 3D Systems). Results: The mean ± standard deviation root mean square value for posterior teeth was 32.2 ± 9.4 in the combination type group and 43.8 ± 11.7 in the all-in-one type group, indicating higher trueness for the combination type (P .05). Conclusion: This study has shown that the final milled prosthesis in combination type CAD/CAM systems had better trueness than the all-in-one system.

Purpose: To estimate the misfit volume of zirconia vs metal-ceramic crowns. Materials and Methods: Five specimens were fabricated from zirconia and five from nichrome (metal-ceramic). Microcomputed tomography techniques were used to obtain volumetric reconstructions of misfit volume before and after ceramic application. Results: The mean misfit volume for metal-ceramic crowns was 8.80 mm3, and for zirconia crowns was 6.76 mm3 (P = .003, 95% confidence interval [CI] 0.714 to 3.358). Misfit volume also did not differ significantly before and after ceramic application (metal-ceramic, P = .375, 95% CI 0.513 to 1.363; zirconia, P = .253, 95% CI 0.257 to 0.977). Conclusion: Zirconia crowns had a smaller mean misfit volume than metal-ceramic crowns. The change in misfit volume after ceramic application was minimal and unlikely to be of clinical relevance.

Purpose: To assess the quality of precision at the implant-abutment interface of single-tooth restorations with titanium and zirconia abutments with hexagonal external connections produced using a digital protocol. Materials and Methods: A total of 20 abutments were produced with commercially pure titanium, and 20 abutments with zirconia, both following a necessary digital protocol. Rotational freedom of all the abutments was assessed. All data were analyzed according to procedures established by software package STATA 14.2. Results: No significant differences relative to rotational freedom emerged between the two groups. Conclusion: This study showed that both types of abutments constantly demonstrated approximately 2 degrees of rotational freedom between implant and abutment where the hexagonal external connection was concerned.

Purpose: To compare marginal adaptation before and after cementation of implant-supported metal-free frameworks fabricated from zirconia, polyetheretherketone (PEEK), or composite. Materials and Methods: Thirty-six CAD/CAM frameworks were constructed from zirconia, PEEK, or composite (n = 12 per material). Marginal gap was measured using a Video Measuring Machine (VMM) system, and repeated-measures analysis of variance was employed for data analysis (P .05). Results: Absolute marginal discrepancies of all frameworks decreased significantly after cementation (P .05). Zirconia and composite frameworks' marginal gap values were clinically acceptable, while PEEK frameworks were judged as being on the borderline of acceptability. Zirconia demonstrated significantly better marginal adaptation than PEEK (P .05). Conclusion: Zirconia showed the best marginal adaptation of the three tested metal-free frameworks.

Purpose: To compare the marginal adaptation of monolithic high-translucency zirconia crowns and porcelain-veneered zirconia crowns. Materials and Methods: A master die was scanned to design and produce 10 porcelain-veneered zirconia copings for layering (PVZ group) and 10 monolithic high-translucency zirconia crowns (HTZ group). The mean vertical marginal gap in both groups was measured from eight predetermined points using a digital microscope. Results: The mean marginal gap in the PVZ group (39.62 ± 18.98 μm) was significantly higher than in the HTZ group (23.54 ± 7.57 μm) (P .05). Conclusion: High-translucency monolithic zirconia crowns had better marginal fit than porcelain-veneered zirconia crowns. Both groups exhibited clinically acceptable marginal discrepancies.