The International Journal of Prosthodontics, 01/2019

Purpose: To assess the effects of maxillary lateral incisor hypodontia treatment following the use of implantation procedures, fixed and removable dental prostheses, and change in the shape of the canine. Materials and Methods: Hypodontia treatment effects were retrospectively evaluated in 129 patients aged 18 to 60 years. The assessment covered esthetic, biologic, and functional aspects of the restored missing teeth within 9 years after treatment. The analysis of the findings took into account the percentage of positive effects of treatment for each method and assessment year and also included statistical tests based on the F statistic, which allowed comparison of the effectiveness of the applied methods of hypodontia treatment. Results: In years 1 to 3, the effects of treatment were wholly positive; in subsequent years, the applied methods differed in terms of effectiveness. After 9 years, there was full clinical success for the implant-prosthetic method and for three-unit porcelain-fused-to-metal (PFM) fixed partial dentures (FPDs), 77.77% success for fiber-reinforced composite (FRC) FPDs, 73.68% for multi-unit PFM FPDs, 67.56% for canine shape change, and 23% for metalalloy removable partial denture (RPD) prostheses. Conclusion: The results of this study indicate that the use of mini-implants with PFM crowns and three-unit PFM FPDs are the most effective treatment methods. A less favorable clinical effect was obtained with the use of FRC FPDs and multi-unit PFM FPDs. Changing the canine shape led to an acceptable clinical effect in over two-thirds of case histories. Metal-alloy RPD prostheses yielded the weakest effects.

Purpose: To evaluate survival rates of adhesive post-endodontic buildups made using composite resin and prefabricated quartz fiber posts. Materials and Methods: This retrospective study included all buildups placed between January 1, 2008, and December 31, 2012, by a single skilled operator using a single-adhesive system and dual-curing cement. Final restorations included direct composites, various types of crowns, and fixed partial dentures. During recall, teeth were inspected by four different dentists, and survival analysis was performed using Kaplan-Meier test. Results: A total of 301 root canal-treated incisors and canines were restored. At repeat follow-up appointments, 291 restorations were still in function after a mean time of service of 7.13 ± 2.11 years. Cumulative survival probability at 9 years was 96.0%. No parameter observed was found by log-rank test to have a statistically significant effect on survival rate. Conclusion: Adhesive buildup with prefabricated fiber posts in anterior teeth is a reliable method of post-endodontic treatment in this given clinical protocol.

Purpose: To investigate whether the inclination of the most distal implant and the cantilever length influence marginal bone loss in implant-supported fixed complete dentures (ISFCDs). Materials and Methods: A novel method using computed tomography images was developed to measure the mesiodistal implant inclination. The cantilever length was measured during ISFCD fabrication. Radiographs were obtained after ISFCD installation at 1 and 3 years after loading. Results: A total of 30 subjects with 62 implants were included. Accumulated marginal bone loss was 0.35 ± 0.49 mm. No significant association was found between marginal bone loss and cantilever length or implant inclination. Conclusion: Implant inclination and cantilever length do not seem to affect marginal bone loss.

Purpose: To characterize the multidisciplinary treatment intervention for patients with nonsyndromic oligodontia, focusing on both the preprosthodontic intervention and the type of prosthodontic and functional occlusal units at the end of treatment. Materials and Methods: A retrospective study on the multidisciplinary treatment of 24 patients with agenesis of 8 to 22 (median 15) permanent teeth was carried out by reviewing the patients' medical records, preprosthodontic surgical and orthodontic procedures, and the final dental and prosthodontic status. Results: A total of 23 patients underwent orthodontic treatment, and one-third of them had additional orthognathic surgery. Presurgical intervention involved bone augmentation in 20 patients and insertion of 2 to 16 implants per patient (median 8). The number of implants was positively correlated with the number of missing teeth (P = .004). At the end of treatment, the number of functional occlusal units ranged from 20 to 28 (median 24). A single-tooth crown was mounted on 167 implants, 32 implants were part of a fixed partial denture, and 29 fixed partial dentures were tooth-borne. Conclusion: The treatment of patients with severe oligodontia is comprehensive and complex. Irrespective of the number of congenitally missing teeth, the final functional occlusion consisted of a minimum of 20 units, which in addition to permanent teeth included preserved deciduous teeth, implants, and fixed partial dentures.

Purpose: To compare clinical outcomes of immediate vs delayed implant loading in edentulous maxillae with full-arch fixed prostheses. Materials and Methods: Two patient groups were identified for this study: (1) the test group (TG), which included 34 patients (19 women, 15 men; mean age 56.7 years) treated with the Columbus Bridge Protocol with 4 to 6 postextractive implants loaded within 24 hours (163 implants total); and (2) the control group (CG), which included 15 patients (6 women, 9 men; mean age 59.96 years) treated with a traditional two-stage delayed loading rehabilitation using 6 to 9 implants inserted in healed sites (97 implants total). All patients were rehabilitated with full-arch fixed prostheses in the maxilla. Results: At the 10-year follow-up, no difference in the implant cumulative survival rate between the TG (93.25%) and CG (94.85%) was found. Mean bone loss was significantly lower in the TG (mean: 2.11 mm) compared to the CG (mean: 2.65 mm). All original prostheses were maintained and functioning satisfactorily. Conclusion: Maxillary full-arch immediate loading represents a valid alternative to the traditional delayed loading rehabilitation.

Purpose: To assess the impact of prosthetic rehabilitation on quality of life (QoL) in patients with cleft lip and palate (CLP) and in edentulous patients with implant-supported complete dentures (ICD). Materials and Methods: CLP (n = 20) and ICD (n = 26) patients completed the Oral Health Impact Profile (OHIP-14). Nine patients with an OHIP-14 score above the 75th percentile were interviewed. Data were interpreted using inductive content analysis and triangulation. Results: ICD patients scored higher than CLP patients in overall OHIP-14 score and in most domains (P .05). After rehabilitation, CLP patients reported improvement in psychosocial functions but worsening in physical functions. ICD patients had improvement in all domains, but were less satisfied. Conclusion: The mixed-methods study design can detect the origins and interactions of factors in treated patients with complex problems.

Purpose: To report implant failure rates in a large group of partially edentulous patients over a long-term period and to analyze possible associations between available clinical variables and implant failure. Materials and Methods: Altogether, 2,453 patients were consecutively provided with 9,167 implants in 2,915 partially edentulous arches (Kennedy Class I or Class II) between 1986 and 2015 at one referral clinic. All implant failures recorded at the clinic during follow-up were identified and analyzed in relation to available clinical variables by means of a multivariable regression analysis. Results: Overall cumulative survival rates (CSRs) for treated arches without any implant failures after 15 and 25 years were 91.7% and 90.3%, respectively, and the corresponding CSRs for implants were 96.1% and 95.3%, respectively. Out of the 209 arches with reported implant failures, 112 were reported with failures during the first year (54%). The strongest associations with risk for overall implant failure were related to two different surgeons (hazard ratio 6.14 [2.77 to 13.60] and 1.51 [1.14-1.99]). Number of implants, time since surgery, calendar year of surgery, and age at surgery were also significantly associated with overall implant failure. Furthermore, early implant failures were associated with implant surface (HR 2.27 [1.43 to 3.57]), indicating higher risk for implants with a turned surface. This variable was not observed for overall or late implant failures. Conclusion: Individual surgeons seem to have an important impact on risk for implant failure in combination with implant surface and number of placed implants during the early period after surgery. Besides the surgeon and number of implants, the overall trend seems to be a decreasing risk for failure the longer the patient is followed up, the later the patient is included, and the older the patient is at treatment.

Purpose: To identify trends in the application of various types of digital technologies in maxillofacial prosthetics by identifying these digital technologies and their characteristics and reviewing the prevalence of applied digital technologies and their recent trends in the maxillofacial prosthetics literature. Materials and Methods: Five leading peer-reviewed prosthodontics journals were manually searched for maxillofacial prosthetics articles on the use of digital technologies published from January 2008 to December 2017. Descriptive statistics were used to analyze data collected on productivity, type of digital technology used, type of article, type of defect, number of authors, and geographic distribution. Results: Of the 336 maxillofacial prosthetics articles screened, 87 (26%) were selected for analysis. A remarkable increase was found in article productivity in the last 5 years (63%) compared to the first 5 years (37%). There was also a notable increase over the last 10 years in all digital technologies used except for evaluation technologies, which remained almost constant. Case reports most frequently mentioned use of digitization technologies (61%), design technologies (66%), and rapid prototyping technologies (66%). Original research articles most frequently mentioned use of evaluation technologies (89%); 39% of these technologies were used for intraoral defects and 27% for extraoral defects. Most often, articles had four to five authors (54%). Most published articles were from the Asia-Pacific region (44%), followed by North America (22%) and Europe (20%). Conclusion: Although the application of digital technologies reported in the maxillofacial prosthetics literature has increased notably in leading prosthodontics journals over the last 10 years, total article productivity has remained relatively small.

Purpose: To assess any correlations between resonance frequency analysis (RFA) and other clinical measurements, namely changes in marginal bone level. Materials and Methods: A systematic review was performed to investigate the relationship between RFA and changes in marginal bone level. Clinical studies published up to May 1, 2018, were searched in electronic databases, including PubMed/MEDLINE, Embase, and Cochrane, using the following MeSH terms: resonance frequency analysis; implant stability quotient; RFA; and ISQ, in combination with marginal bone level; marginal bone loss; and marginal bone resorption. Results: A total of 62 articles were included in this review after all abstracts and full-text articles were examined according to the inclusion/exclusion criteria. The Results and Discussion sections of investigations reporting both marginal bone level changes and RFA measurements were presented. Relevant findings regarding relationships between RFA and bone quality or insertion torque were also summarized. Most articles reported an overall increase in ISQs over the observation time; however, contradictory findings were found regarding the relationships between RFA measurements, marginal bone loss, and other parameters. Conclusion: A definitive conclusion could not be made, as mixed results were found in the few articles that reported significant associations and correlations between RFA measurements and bone loss, while others concluded the opposite. Heterogeneity between the studies further complicated interpretation. Longitudinal RFA measurements may still be valuable for evaluating implant stability when applied as a supplementary tool to radiographic assessments and other clinical examinations.

Purpose: To evaluate and compare the failure and complication risks of porcelain laminate and indirect resin veneer restorations (VRs) by means of a meta-analysis. Methods: An electronic database search was performed in MEDLINE (PubMed), EMBASE (Ovid), and the Cochrane Central Register of Controlled Trials (CENTRAL) databases, and a gray literature search was performed on OpenGrey. All database searches were completed by March 2018. Two authors individually screened the literature according to the inclusion and exclusion criteria. The quality and risk of bias of the included studies were evaluated using the Newcastle- Ottawa scale (NOS) and the Cochrane Handbook for Systematic Reviews of Interventions (CHSRI). The Mantel-Haenszel method was used to synthesize the data of the included studies. All statistical analyses were performed using the software Stata 14.0, and the results were expressed as risk ratio (RR) with 95% confidence interval (CI). Results: Five studies-two randomized controlled trials (RCTs) and three clinical controlled trials (CCTs)-were included in this review. Of the three CCTs, two were assessed to be low quality, and the third was considered high quality. The two RCTs were rated as unclear risk of bias. The meta-analysis results showed the risk of failure for indirect resin VRs was higher than for porcelain laminate VRs (RR: 0.15, 95% CI: 0.06-0.40; P = .000). Fracture and debonding were the main complications leading to failure. For risk of fracture, an RR of 0.18 (95% CI: 0.04-0.71) and a statistically significant difference (P = .015) were found in favor of porcelain laminate VRs. For risk of debonding, there was no statistically significant difference (P = .108) found between the two types of VRs. The results of the sensitivity analysis (RR: 0.09, 95% CI: 0.02- 0.45; P = .004) suggested that this conclusion was reliable. Conclusion: The survival rate of porcelain laminate VRs was higher than indirect resin VRs, and the latter had a higher risk of fracture. However, there was no statistically significant difference in the risk of debonding between the two types of VRs. Porcelain laminate VRs have a better prognosis compared to indirect resin VRs, which provides an evidence-based reference for the selection of VRs in clinical practice.

This invited commentary reviews the use of splinting vs nonsplinting in implant impressions.

Purpose: To investigate the influence of connector diameter on the mechanical load to fracture in monolithic three-unit lithium disilicate fixed partial dentures (FPDs). Materials and Methods: A total of 24 FPDs were designed and manufactured using computer-aided design/computer-assisted manufacturing (CAD/CAM) with connector diameters of 16 mm2, 12 mm2, or 9 mm2 (Groups A, B, and C, respectively; n = 8 for each group). After thermal and mechanical aging, the FPDs were subjected to mechanical load-to-fracture assessment. Results: Fracture loads of Groups B (834 ± 105 N) and C (796 ± 41 N) were significantly lower compared to Group A (990 ± 65 N). Conclusion: Connector dimensions proved to be crucial for fracture resistance of monolithic lithium disilicate FPDs.

Purpose: To analyze the effect of material thickness on the fatigue behavior and failure load of monolithic polymer-infiltrated-ceramic-network (PICN) computer-aided design/computer-assisted manufacture (CAD/ CAM) crowns. Materials and Methods: PICN (VITA Enamic) molar crowns with standard (PICN-ST, 1.5 mm) and reduced (PICN-RED, 1.0 mm) thicknesses were investigated (n = 28). Monolithic zirconia (Z-ST, InCoris TZI) served as control. Failure loads before and after fatigue (1.2 million cycles, 198 N) were evaluated. Data were analyzed pairwise using Wilcoxon rank sum test, and resulting P values were adjusted using the Bonferroni-Holm method, with P .05 considered significant and a prior power analysis. Results: All crowns survived fatigue. Mean failure loads before and after fatigue (respectively) were as follows: PICN-ST: 1,889 ± 341 N and 2,547 ± 876 N; PICN-RED: 2,119 ± 338 N and 2,367 ± 719 N; and Z-ST 5,141 ± 1,194 N and 2,531 ± 682 N. Conclusion: PICN with a reduced thickness of 1 mm appeared to be a reliable CAD/ CAM material for posterior crowns.

Purpose: To calculate the incremental cost-effectiveness ratio (ICER) of prosthetic treatment of a single missing intermediate molar by performing cost-utility analysis on implants, insurance fixed dental prostheses (IFDPs), and private fixed dental prostheses (PFDPs). Materials and Methods: Transition probability (based on the results of past research) and the Markov model were used for cost-utility analysis, and Monte Carlo simulations were performed for sensitivity analysis. The utility values for various types of missing teeth were collected in September 2017, and dental prosthetic treatment was performed in general members of the Japanese population, distributed by sex and age. The time trade-off (TTO) method, which is an index scale (0-1), was used for measuring the utility values. Results: The utility value was the highest when measured at the state in which implant treatment was performed and the lowest when measured in the untreated missing-tooth state. This model showed that compared to FDPs, implant treatment resulted in higher quality-adjusted life years (QALYs). However, the estimated cost over 30 years was lower for IFDPs. The results also showed that PFDPs were in a more extended, dominant state than both IFDPs and implants. The implant-to-IFDP ICER was €2,454.37. Conclusion: The results suggest that implants can be used to obtain higher utility values in comparison to IFDPs and PFDPs. The ICER threshold for 1 QALY in Japan is approximately €37,037 to €44,444, and the implant-to-IFDP ICER was found to be below that found in this study. Accordingly, it appears that implants offer superior cost-effectiveness.

Purpose: To evaluate strain in teeth with differing quality and quantity of tooth surface loss by utilizing surface displacement field measured using digital image correlation (DIC) and strain gauges (SG). Materials and Methods: A total of 80 mesio-occlusodistal preparations were carried out in human maxillary premolars. Ten sound premolars served as a control group, and treated samples were divided into two groups of 40 each according to the composition of the prepared walls (composed of either enamel and dentin [E + De] or dentin only [De]). Each group was then divided into four subgroups of 10 each according to the selected cusp height-to-width ratio (A = 2:1 mm; B = 3:1 mm; C = 3:1.5 mm; D = 4.5:1.5 mm). The samples were uni-axially loaded to 130 N, and strain was recorded using DIC and SG. Results: With SG testing, control samples recorded the lowest strain values and were significantly different from all test groups. However, DIC failed to detect strain in control samples, as it was too low. With DIC, group D showed the lowest strain readings among all the dimension groups and was significantly different from groups A and B, but the composition of the remaining tooth structure did not show any significant effects. With SG testing, remaining wall dimension and composition both had significant effects: Group A scored the highest strain at all compositions, and E + De had better resistance to load stresses than De only. Conclusion: For both testing methodologies, height (≥ 3 mm) and width (1 to 1.5 mm) of the remaining tooth structure had an effect on strain. Tooth compositions of E + De resisted strain better than De counterparts at all dimensions.

Purpose: To investigate the effects of different commercially available computer-aided design/computerassisted manufacturing (CAD/CAM) materials for fabrication of molar crowns, including polyetheretherketone (PEEK), on the fracture strength and failure mode of custom-made titanium and zirconia abutments after artificial aging. Materials and Methods: A total of 48 identical custom-made CAD/CAM abutments milled out of titanium or zirconia were divided into six test groups of eight specimens each. The groups were assigned as follows: titanium abutments restored with zirconia crowns (TiZ), with lithium disilicate crowns (TiL), or with PEEK crowns (TiP); zirconia abutments bonded to a titanium base and restored with zirconia crowns (ZrZ), with lithium disilicate crowns (ZrL), or with PEEK crowns (ZrP). The specimens were artificially aged in a chewing simulator for 1.2 million cycles of dynamic loading with simultaneous thermal cycling and then loaded to fracture in the universal testing machine. Shapiro-Wilk test was used to test for normality. Oneway analysis of variance followed by post hoc analysis using Bonferroni test was used to detect statistically significant differences among groups. Results: All specimens survived the artificial aging process simulating 5 years of clinical service. The fracture patterns and means of the fracture strength (N) varied between groups: TiZ = 4,926 N; TiL = 3,706 N; TiP = 3,878 N; ZrZ = 5,529 N; ZrL = 2,826 N; and ZrP = 3,967 N. Conclusion: Although the tested combinations showed different fracture patterns and loads, all tested abutment and crown materials and their different combinations could be considered to have fracture strengths suitable for clinical application.

Purpose: This in vitro study aimed to evaluate the accuracy of surgical templates fabricated using three different 3D printing technologies. Materials and Methods: Ten identical surgical templates were printed using four 3D printers (two of an identical make and model). Each of the surgical templates was scanned by a reference scanner and then imported into the inspection software. Inspection software utilized a best-fit alignment to automatically calculate the 3D variation at all points. Results: Statistically significant differences were found among the three groups (χ2[2] = 12.880, P = .0016). Mean 3D deviation was also significantly different between the two printers of an identical make and model (χ2[1] = 8.251, P = .0041). Conclusion: All of the tested printers had a high level of accuracy in the fabrication of surgical templates, which would justify the trial of cost-effective printers for clinical fabrication of surgical implant templates.

Purpose: To measure the softening via swelling of a composite resin by evaluating its surface hardness after the application of four monomer systems. Materials and Methods: A total of 40 specimens made of a hybrid composite resin were evaluated. Four monomer systems were used as surface-conditioning primers during five exposure times. Surface microhardness measurements (n = 8) were made after application of the monomer systems. Results: In all exposure times, Scotchbond Universal showed the highest influence on the composite resin surface softening (P .05), followed by Stick Resin (P .05). Conclusion: Surface softening of composite resins might be achieved with monomer systems, especially with Scotchbond Universal, which may have a positive influence when repairing aged composite resin restorations.

Purpose: To evaluate the influence of fabrication processes on the mechanical properties of denture base resins. Materials and Methods: Flexural strength, fracture toughness, and Vickers hardness were measured on a conventional pack-and-press resin (PRO), a resin for injection molding (CAP), and a CAD/CAM disc (CAD). Results: For maximal flexural strength, PRO (97.31 MPa) was stronger than CAD (87.98 MPa) and CAP (79.35 MPa). CAD displayed hardness similar to PRO and high fracture toughness. Conclusion: CAD/CAM denture base resin mechanical properties result from the evolution of denture base materials, combining highimpact fracture toughness and improved flexural strength and hardness.

This case history report describes the dental management of a child with ectodermal dysplasia with the premise that appropriate and early dental management positively impacts the oral health-related quality of life of such patients, irrespective of the age at which treatment is initiated.

In most cases, prosthetic rehabilitation of patients suffering from microstomia is inconvenient for the patient and challenging for both the dentist and dental technician. In such cases, conventional impressiontaking requires an individualized tray design and modified impression techniques, amplifying the risk for impression and cast deformation and thereby compromising the final outcome. An intraoral scanner (IOS) might overcome these limitations due to its reduced size compared to an impression tray. In the present case history report, a microstomia patient was successfully restored with a telescopic prosthesis by digitizing both retaining teeth and the palate with an IOS.