The International Journal of Prosthodontics, 03/2015

Classification systems for all-ceramic materials are useful for communication and educational purposes and warrant continuous revisions and updates to incorporate new materials. This article proposes a classification system for ceramic and ceramic-like restorative materials in an attempt to systematize and include a new class of materials. This new classification system categorizes ceramic restorative materials into three families: (1) glass-matrix ceramics, (2) polycrystalline ceramics, and (3) resin-matrix ceramics. Subfamilies are described in each group along with their composition, allowing for newly developed materials to be placed into the already existing main families. The criteria used to differentiate ceramic materials are based on the phase or phases present in their chemical composition. Thus, an all-ceramic material is classified according to whether a glass-matrix phase is present (glass-matrix ceramics) or absent (polycrystalline ceramics) or whether the material contains an organic matrix highly filled with ceramic particles (resin-matrix ceramics). Also presented are the manufacturers' clinical indications for the different materials and an overview of the different fabrication methods and whether they are used as framework materials or monolithic solutions. Current developments in ceramic materials not yet available to the dental market are discussed.

Purpose: The aim of this retrospective cohort study was to evaluate the clinical performance of tooth-supported zirconia-based fixed dental prostheses (FDPs) made by 15 members of the Italian Academy of Prosthetic Dentistry over a time period of up to 5 years. Materials and Methods: Ninety-eight patients were treated with a total of 137 zirconia-based FDPs in anterior and posterior regions using primarily chamfer or knife-edge tooth preparations. The cohort group with parafunctional habits was compared with patients without parafunctional habits according to the esthetic, functional, and biologic United States Public Health Service criteria modified by the FDI World Dental Federation. Results: The estimated cumulative survival of all restorations was 94.70% ± 1.25% standard error (SE), whereas the estimated cumulative success decreased to 89.78% ± 2.58 SE. Mechanical failures, including three zirconia framework fractures, two hairline cracks, nine chippings, and one delamination of the ceramic veneering, were recorded during the 1- to 5-year observation period. An odds ratio of 2.02 (95% confidence interval: 0.67 to 6.12) showed a moderate association between parafunction and failure. Conclusions: Zirconia-based tooth-supported FDPs showed promising clinical results over a period of up to 5 years. Technical complications were more commonly detected in patients with parafunctional habits.

Purpose: The aim of this retrospective cohort study was to evaluate the clinical performance of zirconia-based implant-supported single crowns and fixed dental prostheses (FDPs) made by 15 members of the Italian Academy of Prosthetic Dentistry (AIOP) over a time period of up to 5 years. Materials and Methods: One hundred thirtyone patients were treated with a total of 210 zirconia-based single crowns and FDPs on implants in anterior and posterior regions. A cohort group with parafunctional habits was compared with patients without parafunctional habits according to the esthetic, functional, and biologic United States Public Health Service criteria modified by the FDI World Dental Federation. Results: The estimated cumulative survival (ECS) and standard error (SE) of all restorations on implants was 91.95% ± 1.39%, and the estimated cumulative success (ECSs) and SE was 88.37% ± 1.72%. The ECS of single crowns and FDPs was 91.25% ± 3.69% and 95.23% ± 2.28%, respectively, and the estimated cumulative success rates were 88.84% ± 2.05% and 87.96% ± 3.16%, respectively. Mechanical failures, including four zirconia core fractures, three hairline cracks, four chippings, and five delaminations of the ceramic veneering material, were recorded during a 1- to 5-year observation period. The odds ratio of 3.39 (95% confidence interval: 1.18 to 9.73) showed a moderate association between parafunction and failure. Conclusions: Zirconiabased implant-supported restorations showed encouraging clinical results over a period of up to 5 years, but more clinical data are needed before these restorations can be considered a viable treatment alternative. Mechanical failures were primarily observed in patients with parafunctions.

This study investigated the positional relation of the commissure line of the mouth to the maxillary first molars. Thirty-five volunteers, 20 to 40 years old, with normal natural dentitions were recruited. Maxillary casts with marks locating the commissure were digitally scanned to measure the vertical distance from the tip to the base of the mesiofacial cusp (CO) and from the tip to the mark (CM). There was no significant difference (t test; P > .05) between the CO (1.61 ± 0.41 mm) and CM (1.14 ± 0.68 mm). The mean distance of the commissure mark from the occlusal plane was 0.78 mm.

Purpose: The aim of this long-term cohort study was to evaluate the efficacy and complications of fixed partial dentures in a convenience sample of 100 patients with periodontal disease who were treated and maintained periodontal patients after 20 years. Materials and Methods: After active treatment, including periodontal surgery and endodontic and prosthetic treatment, patients were enrolled in a supportive periodontal care (SPC) program with 3- to 6-month recalls. All patients showed clinical data recorded at (1) the original consultation (T0), (2) the first SPC visit following the completion of prosthetic treatment (T1), and (3) at the latest SPC clinical session 20 years after T1 (T2). Multivariate analyses were performed to investigate the influence of clinical variables on the risk of prosthetic abutment (PA) loss after 20 years' visits. Results: The final sample comprised 100 patients. At T1, a total of 948 PAs represented the original sample of experimental teeth. At the 20-year follow-up, a total of 854 PAs (90.1%) were still in function, while 94 (9.9%) PAs in 41 patients (41%) were lost during SPC; 98% of lost PA were endodontically treated. Vertical root fracture (48%) was the major cause of PA loss, while progression of periodontitis caused 31% of PA loss. Age (P = .002), Full-Mouth Plaque Score (P .0001), Full-Mouth Bleeding Score (P = .0002), and oral parafunctions (P = .0083) were associated with increased probability of PA failure. Among clinical-related factors, endodontic treatment (P = .0082), root resection/ amputation (P .0001), multi-rooted teeth (P = .0005), and abutment associated with parafunction (P .0001) were associated with increased risk of abutment loss after 20 years. Conclusions: Perioprosthetic treatment in compliant patients is highly successful after 20 years of SPC.

Purpose: This study aimed to investigate the impact of preradiation tooth loss in patients with head and neck cancer. Materials and Methods: Records of 397 (partially) dentate patients who were referred for preradiation oral screening were included. Number and location of teeth lost and occluding pairs lost were determined for different tumor locations. Results: The majority of patients (54%) were affected by tooth loss. Proportion of teeth lost, their location, and proportion of occluding pairs lost were not evenly distributed across tumor locations. The highest proportions of teeth were removed with oral tumors (maxilla: 25%; mandible: 47%). For preradiation preventive extractions only, ie, not taking into account teeth that were lost due to ablative surgery, tooth loss in the mandible was still not evenly distributed across tumor locations, but tooth loss in the maxilla and occluding pairs lost were. Conclusions: Tumor location affects preradiation tooth loss, though this is primarily a consequence of ablative surgery rather than a consequence of preradiation dental extraction decisions. Since patients with oral cavity tumors are affected most by preradiation tooth loss, treatment planning with regard to functional rehabilitation is desirable for this patient group in particular.

Purpose: The amount of coronal residual structure has been recognized as critical to the survival probability of pulpless teeth. The aim of this study was to analyze whether and how coronal dentin loss would affect the failure rate of fiber-reinforced composite (FRC) post-core restorations. Materials and Methods: Eligible studies were searched in PubMed, Cochrane Library, Embase, and China National Knowledge Infrastructure databases from their inception through April 2014. The risk ratio with 95% confidence interval (CI) was estimated using the Mantel and Haenszel method. Results: Five studies were included in this meta-analysis. The risk ratio for coronal wall absence was 2.73 (95% CI: 1.48-5.03). The risk ratio for ferrule absence was 1.94 (95% CI: 0.57-6.54). Conclusions: This meta-analysis of the limited studies available suggested that coronal wall absence might increase the risk of FRC post-core restoration failure, while the role of ferrule effect is still not entirely understood.

Purpose: This study aimed to compare the viscoelastic properties and antimicrobial activity of a soft liner with and without silver zeolite for a period of 4 weeks. Materials and Methods: Thirty edentulous patients wearing complete dental prostheses were selected. A uniform space was created in the intaglio surface of their maxillary prosthesis, and a soft liner without silver zeolite (control material: S) was applied. After 28 days, the soft liner was replaced with new soft liner containing silver zeolite (test material: SZ) and worn for another period of 28 days. Viscoelastic analysis was conducted on the prostheses using S and SZ materials for newly formed samples (T0) and on samples collected after the 28-day period (T28). Culture tests were performed on both materials at T28. Statistical analysis was done using Student independent t test. Results: The decrease in elasticity from T0 to T28 was found to be 76.49% and 79.11% and the decrease in viscosity was 76.49% and 80.3% for the S and SZ materials, respectively. Hence, the difference was not significant. The mean colony-forming units (CFUs) of Candida albicans and gram-negative bacteria in the S material at T28 days was 3,150 ± 1,251, whereas that of the SZ material was 1,084 ± 662. There was a statistically significant difference in the mean CFUs between the two groups (P .05). Conclusions: The addition of silver zeolite to the soft liner improved the antimicrobial activity while not affecting significantly its viscoelastic properties.

Purpose: The effect of renewing removable dentures on masticatory function was evaluated according to the occlusion offered by different types of mandibular arches. Materials and Methods: Twenty-eight patients with complete maxillary dentures were subdivided into three groups in terms of mandibular dentition type: dentate, partial denture, and complete denture. The participants were observed before and 8 weeks after maxillary denture renewal. The mandibular denture was also renewed in the partial and complete denture groups. The participants masticated carrots, peanuts, and three model foods of different hardnesses. The particle size distribution of the boluses obtained from natural foods was characterized by the median particle size (d50) in relation to the masticatory normative indicator (MNI). Chewing time (CT), number of chewing cycles (CC), and chewing frequency (CF) were video recorded. A self-assessment questionnaire for oral health-related quality of life (Geriatric Oral Health Assessment Index [GOHAI]) was used. Statistical analyses were carried out with a mixed model. Results: Renewal of the dentures decreased d50 (P .001). The number of participants with d50 values above the MNI cutoff decreased from 12 to 2 after renewal. Renewal induced an increase in mean CF while chewing model foods (P .001). With all foods, renewal tended to affect CT, CC, and CF differently among the three groups (statistically significant renewal × group interactions). The GOHAI score increased significantly for all groups. Conclusions: Denture renewal improves masticatory function. The complete denture group benefited least from renewal; the dentate group benefited most. This study confirmed the usefulness of denture renewal for improving functions and oral health- related quality of life.

Zirconia ceramic disks (Cercon) were fabricated using a computer-aided design/ computer-assisted manufacture system and fitted to hard tooth tissues from freshly extracted bovine mandibular incisors using seven cements (zinc phosphate, zinc polycarboxylate, Eco-Link, Panavia F 2.0, Clearfil SA Cement, MaxCem Elite, and GC Fuji Plus) with various physicochemical and bonding properties. Bond strengths were determined using a universal testing machine (Hounsfield H5KS) with a 5,000-N head and a cutting knife speed of 0.5 mm per minute. The study showed that the strongest bond between zirconia ceramic and hard tooth tissues was obtained with Panavia F 2.0 adhesive cement based on 10 methacryloyloxydecyl dihydrogen phosphate monomer.

This study tested the possible damage to the internal implant connection provoked by repeated disconnection and reconnection of prosthetic components. Using a light-structured scanner, connection deformation was inferred by threedimensional (3D) positional changes of a "reference" abutment before and after multiple dis- and reconnections. Measurements were taken after 1, 2, 5, 10, and 20 insertions of titanium abutments in 16 internal hexagon implants. Statistical analysis revealed that multiple dis- and reconnections could cause a deformation in the implant-abutment connection, proportional to the number of insertion procedures. However, below the threshold of 10 cycles, 3D deformation values were minimal.

Purpose: This survey aimed to review how scientific articles were reported and to describe the types of statistical tests that had been recently and commonly used in The International Journal of Prosthodontics. Materials and Methods: All 174 articles published in 2012 and 2013 were hand-searched to identify scientific articles (n = 151) and those using at least one statistical test to explore results (n = 111). Editorials, letters, comments, erratum, and award proceedings were excluded. The number and type of statistical tests used within articles were collated, and the 10 commonly used methods were identified and described. Results: Of the 151 scientific articles, 76% (n = 111) used at least one statistical test and 24% (n = 40) used qualitative methods. Up to 10 tests were used per article, with 237 in total, of which 36 were unique. The 10 most commonly used tests were analysis of variance (ANOVA; n = 34), survival analyses (n = 29), Student t test (n = 19), chi-square (n = 19), Mann-Whitney U (n = 14), logistic regression (n = 13), Wilcoxon signed rank (n = 12), Fisher exact (n = 11), log-rank (n = 10), and Cox proportional hazards (n = 8), and they accounted for 71% (n = 169) of all tests used. Conclusions: The vast majority of articles published in recent years in The International Journal of Prosthodontics employed statistical analyses. Across 2 years, nearly 250 tests were completed, including 36 unique tests. Statistical test use was common but diverse.