The International Journal of Prosthodontics, 02/2021

Purpose: To investigate whether pretreatment patient satisfaction, oral health-related quality of life, or diagnostic complexity are predictive of a decision to choose implant treatment. Materials and methods: Edentulous patients requesting dentures were enrolled in a prospective observational study. All subjects were provided with conventional dentures and then given the option to proceed with the placement of two mandibular implants and to have their prosthesis modified into an implant overdenture. Subjects were classified according to the Prosthodontic Diagnostic Index (PDI-CE) and asked to complete a Denture Satisfaction Questionnaire and the Oral Health Impact Profile for edentulous patients (OHIP-EDENT) at pretreatment, following the provision of new dentures, and following modification to overdentures. Results: Of the 125 subjects who had conventional dentures, 15 proceeded with implant treatment. The subjects who decided to have implants were not significantly different in terms of diagnostic complexity or level of satisfaction. Those who chose implants were significantly younger, had newer dentures, and had higher OHIP-EDENT scores at baseline. The most common reason for not being satisfied with dentures but avoiding implants was fear of surgery. Conclusion: The majority of subjects in this study were satisfied with conventional denture treatment, despite registering its limitations. Subjects who were more anatomically compromised were not more likely to choose implant treatment. It remains to be shown whether fear of surgery can be overcome in order to increase the uptake of implant treatment and improve patient outcomes.

Purpose: To assess patient self-perception of overall dental appearance and of potentially localized dyschromic teeth and to compare them to the perception of the treating dentist. Materials and methods: A sample of 160 patients from Cluj-Napoca, Romania, answered a questionnaire regarding the self-perception of their dental appearance and of potential localized dental discolorations. The same questions were answered by their dentist, without knowing their answers, after clinical examination of each patient. Each patient and the dentist were asked to indicate a tooth with a pleasant color to be considered as reference. Color measurements of teeth indicated as dyschromic and of the reference teeth were performed using a spectrophotometer. Color differences were calculated using the ΔE₀₀ formula. Results: Tooth color was considered the most disturbing factor of their dental appearance by 41.25% of patients. Most patients (58.12%) acknowledged localized dyschromic teeth in their dental arches. Agreement between patients and dentist regarding the identification of dyschromic teeth was found in 61.87% of cases. The DE₀₀ between the reference teeth and the teeth considered dyschromic by both patients and dentist ranged between 0.8 and 23.1. Disagreement between patients and dentist was found in 38.12% of situations. For teeth considered dyschromic only by patients, the ΔE₀₀ ranged between 0.8 and 23.1. For teeth considered dyschromic only by the dentist, the ΔE₀₀ ranged between 0.8 and 25. Conclusion: Most patients expressed concerns regarding their overall dental color and perceived themselves as having teeth with localized dyschromia. More than a third of the investigated patients had different perceptions regarding dyschromic teeth compared to their dentist. The majority of ΔE₀₀ values calculated between dyschromic and reference teeth exceeded the perceptibility and acceptability thresholds.

Purpose: To systematically evaluate and compare the clinical performance of lithium disilicate (LDS)- and zirconium dioxide (ZrO₂)-based ceramic monolithic crowns in the posterior dentition. Materials and methods: Treatment was administered by two experienced general dental practitioners in two public dental health care clinics. Forty-four patients received 60 crowns randomized to be either LDS or ZrO₂ and cemented with resin cement. Evaluations were performed after 3 years using California Dental Association criteria. Results: The mean follow-up time was 40 months (range: 31 to 50). No crown fractured during the observation time, and no chip-off fractures occurred. The success rate for ZrO₂ was 80%, and the survival rate was 93.3%. For LDS, the success rate was 89.7%, and the survival rate was 100%. Survival after 3 years for all crowns together was 96.6%, and success was 84.7%. There was no significant difference between the two materials. Conclusion: Crowns made of monolithic translucent ZrO₂ and LDS show equal and promising clinical results from a short-term perspective. There seems to be a difference between how patients and professionals rate crowns concerning esthetics (color and shape), with patients rating the restorations more favorably.

Purpose: To compare the efficacy of low-dose laser therapy to that of conservative treatment using two different occlusal splints (stabilization and anterior repositioning splints) in patients with internal derangements of the temporomandibular joint (TMJ). Materials and methods: The study population consisted of patients with disc displacement with reduction diagnosed according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) Axis I and Axis II. In addition, disc displacement with reduction was confirmed in all patients using TMJ ultrasonography. These tests were conducted for 6 months with an interim control in the third month. The "clicking" sound from the joint on opening and closing the mouth and the extent to which the mouth opened vertically and laterally were assessed. In all, 20 patients received low-dose laser therapy, 20 were treated with a stabilization splint, and 20 were treated with an anterior repositioning splint. In addition, 10 untreated patients were included as a patient control group, and a further 10 healthy subjects were included as a healthy control group. Changes in the condition were assessed based on the results of the RDC/TMD Axis II and with the use of an algometer. Results: The anterior repositioning splint group showed improvement in the "clicking" sound during mouth opening. Lateral movement improved significantly in patients who received laser therapy. In the patient control group, the click disappeared during mouth opening, the algometrically determined pain improved, and the lateral movement increased. There were no statistically significant differences between groups in the improvement of vertical mouth movement or in the clicking sound during mouth closing. Conclusion: Each treatment modality applied in this study separately produced positive results for the clicking sound, restrictions in vertical and lateral movements, and reduction of the pressure pain threshold observed in cases of TMJ irregularity. The decision regarding which treatment modality should be employed can be made based on the patient's symptoms. However, this study also indicates that TMJ derangements can resolve spontaneously when left untreated.

Purpose: To present medium- and long-term biologic outcomes of implant-supported single-tooth restorations and fixed partial dentures and to analyze their correlations with prosthesis and patient characteristics. Materials and methods: The records of patients treated with implant-supported fixed restorations between 2004 and 2019 reporting the presence or absence of peri-implantitis and/or implant failure were analyzed. The cumulative survival rate (%) over time was calculated, as well as the cumulative prevalence of units free of peri-implantitis. Results: A total of 344 implants in 112 patients were included, with a mean follow-up period of 5.3 ± 4.0 years after loading. The cumulative survival rates for implants supporting single crowns and fixed partial dentures were 98.11% and 100% after 5 years, respectively, and 97.43% and 98.96% after 10 years, with an overall survival rate of 91.69% after 12 years. At the patient level, the implant survival rates were 95.42%, 92.73%, and 85.31% at 5, 10, and 12 years, respectively. The cumulative rate of implants free from peri-implantitis was 87.46% at the implant level and 72.39% at the patient level. Implant and prosthesis characteristics did not affect the long-term occurrence of implant failure or peri-implantitis. The development of peri-implantitis was statistically correlated with patient smoking habits, but not with history of periodontitis or with diabetes mellitus. Conclusion: Implants supporting single crowns and fixed partial dentures showed relatively high medium- and long-term survival rates that were not influenced by the implant or prosthesis characteristics, including the retention method. As for patient characteristics, only smoking was correlated with the occurrence of peri-implantitis.

Purpose: To assess the success rates of cone beam computed tomography (CBCT) in identifying the locations and directions of abutment screw access holes (ASAHs) in metal-ceramic and all-ceramic implant restorations. Materials and methods: Thirty-two implants were inserted into four clear acrylic casts. Metal-ceramic and all-ceramic crowns were placed on the inserted implants in two successive tasks. A maxillofacial radiologist determined the locations and angles of the ASAHs based on the CBCT images that were taken from the casts. Locations obtained from the CBCT images were carefully transferred to the crowns as access points. A prosthodontist pierced the crowns along the proposed access points and in the direction determined based on the CBCT images. Proper crown removal was considered to be the mark of success of CBCT in detecting ASAH location and direction. Fisher exact and chi-square tests were used to compare the results between the two types of restoration. Results: Success rates of CBCT for defining ASAH location and direction were, respectively, 96.9% and 93.8% in metal-ceramic restorations and 78.1% and 59.4% in all-ceramic restorations. There were no significant differences between the two restoration types regarding the detection of location in either molar (P = .333) or premolar (P = .226) crowns. Abutment angle did not affect the success rate of CBCT in determining ASAH location or direction in metal-ceramic restorations. Conclusion: CBCT images define the locations and directions of ASAHs in metal-ceramic restorations more reliably than in all-ceramic restorations. In contrast to the metal-ceramic crowns, the success rate of CBCT in all-ceramic crowns is more dependent on abutment angle and crown morphology.

Purpose: To examine the effect of tightening and loosening the dental implant screw on implant osseointegration in an elderly rat model. Materials and methods: Titanium dental implants were inserted in the bilateral tibiae of 34 elderly Wistar rats (1 year and 3 months old). Rats were randomly divided into five groups: control (no loading); immediate loading (IL) (vertical load [3 Hz for 15 minutes/day] immediately after implantation); early loading (EL) (load started on postoperative day 7); five times abutment removal (R5) (tightening and loosening of the abutment screw once per day for 5 days each week); and two times abutment screw removal (R2) (tightening and loosening of the abutment screw once per day for 2 days each week). After 4 weeks, the rats were euthanized, and the bone structure surrounding the dental implants was evaluated using microcomputed tomography analysis. Results: Osseointegration failed more frequently in the EL, R2, and R5 groups than in the control and IL groups (P = .06). The EL, R2, and R5 groups also tended to have lower relative gray values than the control and IL groups. Conclusion: Tightening and loosening the abutment screw might negatively affect dental implant osseointegration in the early healing stage in older adults.

Purpose: To evaluate the color stability and mechanical properties of two commonly used maxillofacial silicone elastomers after addition of pigments and opacifiers and before and after artificial aging. Materials and methods: This study evaluated two maxillofacial silicone elastomers: A-2000 and M511. Two different pigment and opacifier systems (e-Skin and Reality Series) were used with the elastomers. Control groups (no pigment or opacifier) and experimental groups (each with subgroups containing additional pigments and/ or opacifiers) were fabricated for each of the silicone elastomers. A total of 51 specimens were evaluated for color stability, and 100 for mechanical properties. A spectrophotometer was used to assess CIE L*a*b* values before and after aging. CIELAB 50:50% perceptibility threshold (ΔE* = 1.1) and acceptability threshold (ΔE* = 3.0) were used to interpret color changes. A durometer and universal testing machine were used to evaluate the mechanical properties. ANOVA and Fisher least significant difference (LSD) test were performed to determine the statistical significance of the results (P < .05). Results: Significant differences in color measurements (ΔE*) were found for all silicone groups following artificial aging (P < .05). ΔE* values for the mixed pigment/opacifier subgroups of both elastomers were below the perceptibility threshold. Additionally, after aging, the hardness, tear strength, and tensile strength significantly increased for all silicone groups (P < .05), while percent elongation significantly decreased (P < .05). Conclusion: Artificial aging affected the color stability and mechanical properties of the pigmented silicone elastomers with added opacifier. Overall, A-2000 with e-Skin group displayed the most color stability, with its mechanical properties being the least affected by artificial aging.

Purpose: To compare the accuracy of posts fabricated using a conventional direct technique with casting to the accuracy of posts fabricated using a fully digital protocol with CAD/CAM technology and selective laser melting. Materials and methods: Ten extracted permanent maxillary incisors were endodontically treated and prepared for a post. For each tooth, two metal posts were fabricated, one by casting (Group C) and one by a fully digital protocol (Group D). Accuracy of fit was analyzed with computed microtomography (μCT) to compare the space volume, the space area, and the distance between the post and the prepared root canal wall among posts. Results: The mean and SD values of the overall space volume and the distance between the post and the prepared root canal wall, respectively, were: Group C: 2.22 ± 1.35 mm³ and 53.66 ± 23.39 μm; Group D: 3.82 ± 0.45 mm³ and 89.47 ± 19.30 μm. The values for the Group C posts were significantly lower (P = .002). All space volume values in all measured sections were significantly lower for the Group C posts. The mean distance and the space area between the post and the prepared root canal wall in the apical sections 3 (P < .001 for both) and 4 (P = .0019; P = .004, respectively) were significantly lower in Group C. No significant differences were calculated in cervical sections 1 and 2. Conclusion: Both methods of post manufacturing were similarly accurate in the cervical part of the prepared root canal; however, a significant difference regarding the accuracy of both methods was determined for the apical parts of the posts.

Purpose: To investigate whether high-level irradiance and short light exposure times with light-emitting diode (LED) curing units could provide bond strength comparable to halogen lights for ceramic laminate veneers (CLVs). Materials and methods: A total of 160 extracted human maxillary central incisors were prepared to receive CLVs (lithium disilicate) in shades A1 and A3.5. CLVs were luted with light-curing (LC) and dual-curing (DC) resin cements using four protocols: 3 seconds in extra power mode, 8 seconds in high power mode, or 10 seconds in standard mode with an LED unit, or 40 seconds with a conventional halogen light from all aspects (n = 10). Following thermal cycles, shear bond strength test was performed with a universal testing machine. Data were analyzed using one-way analysis of variance and post hoc Tukey test. Failure modes were classified under a stereomicroscope, and data were analyzed using Pearson chi-square test (P = .050). Results: According to the intragroup comparison of different irradiation protocols, the mean shear bond strength of the A1-LC-10 group was found to be significantly higher than that of the A1-LChalogen group (P = .026). Shear bond strength values of the A1-LC-10 group and A3.5-LC-10 group were significantly higher than that of the A3.5-DC-10 group (P = .003). The A3.5-DC-3, A3.5-LC-3, and A1-DC-8 groups revealed the significantly most adhesive failures, and the A1-LC-8 group revealed the most mixed failures (P < .001). Conclusion: Both light and dark ceramic shades with LC cement combination responded the best to the standard mode of 10-second exposure time with LED application. However, with conventional halogen light application, the highest bond strength values were obtained with DC cement and light ceramic shade combination.

Purpose: To systematically review the influence of abutment material and configuration on the soft tissue esthetic outcomes of implant-supported single crowns (iSCs) after 3 years. Materials and methods: An electronic search on MEDLINE (PubMed) from January 2000 to July 2019 was conducted for clinical trials with no language restrictions. The focus question was: In partially edentulous patients with iSCs, does the abutment material (metal vs ceramic) or the configuration (standardized vs customized) have an effect on the soft tissue esthetic outcomes? Randomized controlled trials, controlled clinical trials, and prospective or retrospective case series with at least 10 patients and a minimum of 3 years of follow-up were included. The esthetic outcomes Pink Esthetic Score (PES), PES/White Esthetic Score (WES; ie, modPES), Papilla Index (PI), soft tissue recession, and papilla height change were extracted. Meta-analysis was performed when applicable. Results: Of the 6,399 titles identified, 27 studies were included. Combined mean PES/modPES scores, translated into a scale of 0 to 100, were 68.8 for ceramic, 74.2 for metal (P = .392), 71.9 for customized, and 71.3 for standard (P = .981) abutments. Mean soft tissue recession was also similar between the abutment groups, abutment material (P = .850), and configuration (P = .849), ranging from -1.09 mm to +0.59 mm gain. Papilla height changes ranged from -1.22 mm to +1.0 mm gain. The reported mean PI was 2.16 for customized, 2.06 for standard (P = .552), 2.01 for ceramic, and 2.28 for metallic (P = .04) abutments. Conclusion: This systematic review showed that the abutment material and configuration had minimal impact on the evaluated soft tissue esthetic outcomes. Future research focusing on the included parameters in a randomized controlled manner is needed to validate the present findings.

Purpose: To evaluate the trueness of two intraoral scanners in different clinical situations and considering operator experience. Materials and methods: Two intraoral scanner systems were used to perform a total of 120 digital impressions of three master casts reproducing three scenarios (single implant, two implants, and four implants [full-arch]). Two operators, one experienced and one unexperienced, were selected. Results: No differences were found between the two operators. A statistically significant correlation was found with regard to the scanning system used and the clinical scenario analyzed. Conclusions: Within the limits of this preliminary report, operator experience seems not able to significantly influence the trueness of a digital impression; however, imprecision increased in the full-arch cases for both operators. The twoimplant scenario presented similar trueness values for both scanner systems.

Purpose: To assess the absolute linear distances of three different intraoral scan bodies (ISBs) using an intraoral scanner compared to a conventional impression in a common clinical model setup with a gap and a free-end situation in the maxilla. Materials and methods: An implant master model with a reference cube was digitized using x-ray computed tomography and served as the reference file. Digital impressions (TRIOS, 3Shape) were taken using three different ISB manufacturers: NT Trading, Kulzer, and Medentika (n = 10 per group). Conventional implant impressions were taken for comparison (n = 10). The conventional models were digitized, and all models (digital and conventional) were superimposed with the reference file to obtain the 3D deviations for the implant-abutment-interface points (IAIPs). Results for linear deviation (trueness and precision) were analyzed using pairwise comparisons (P < .05; SPSS version 25). For precision, a two-way factorial mixed ANOVA was used. Results: The deviations for trueness (mean) ± precision (SD) of the IAIPs ranged as follows: FDI region 14 = 0.106 ± 0.050 mm (Medentika) to 0.134 ± .026 mm (NT Trading); region 16 = 0.108 ± 0.046 mm (conventional) to 0.164 ± 0.032 mm (NT Trading); region 24 = 0.111 ± 0.050 mm (conventional) to 0.191 ± 0.052 mm (Medentika); region 26 = 0.086 ± 0.040 mm (conventional) to 0.199 ± 0.066 mm (Kulzer). There were significant differences for trueness between all digital and conventional impression techniques. For precision, only two significant differences in two implant regions (14, 24) were observed. Conclusion: Longer scanning paths resulted in higher deviations of the implant position in digital impressions. Due to algorithms implemented in the software, errors resulting from the different scan bodies may be reduced during the alignment process of the IOS in clinical practice.

Tissue retraction devices (TRDs) are used for head and neck radiotherapy to displace soft tissues and fixate the mandible. They can increase the accuracy of irradiation and reduce its side effects, such as oral mucositis. However, no method has been described for fabrication of TRDs in edentulous patients. In this case report, an edentulous 67-year-old patient undergoing radiotherapy of the tongue was provided with a TRD. The tongue was immobilized, ensuring irradiation consistency and the retraction of healthy oral tissues. Using 3D printing, an efficient workflow for fabrication of TRDs based on the patient's existing complete prostheses can be realized.