The International Journal of Prosthodontics, 06/2007

Purpose: To assess oral health and prosthodontic conditions of Chinese adults and the changes in these conditions over time. Materials and Methods: PubMed was searched by combining the keyword China with dental health survey, oral health, tooth loss, DMFT (decayed/missing/filled teeth), dental prosthesis, or dentures. After selection, 12 studies remained. Data were obtained from these studies on DMFT, DMFT components, and teeth present and were tested against the following independent variables using analysis of variance: age, residence, and year of data collection. Results: DMFT increased with age (P = .0001). Rural subjects presented higher DMFT based on the higher "decayed" component (P = .003), which increased markedly for subjects over 45 years of age. The number of teeth present decreased with increasing age (P = .0002). The results showed that Chinese subjects who are 65 years old have an average of 20 teeth. Urban subjects had more teeth present (P = .05), although no difference was seen for the "missing" component of DMFT. In general, few prosthodontic data could be extracted from the selected studies, and these data were often unspecific or inconclusive. Conclusions: The "filled" component of DMFT remained consistently low for all ages, indicating limited care. All outcomes were independent from year of data collection, indicating unchanged care. Outcome aggregation on the number of functional teeth and prosthetic care was impossible. For future reports, it is recommended to include additional information about location and function (in terms of occluding pairs) of teeth present when describing oral health status.

The aim of this in vitro study was to evaluate the influence of the impression tray and viscosity of the wash material on the dimensional accuracy of impressions taken using a 2-stage putty-wash technique. Identically shaped metal stock trays (MeTs) and disposable plastic stock trays (DiTs) were used for taking impressions (n = 10) of a mandibular cast (4 abutments) with 2 different impression materials. Dies were poured and the relative diameter deviation was calculated after measurement. Zero viscosity of the materials was determined. Dimensional accuracy was significantly affected when DiTs were used. Lower-viscosity wash materials led to more precise impressions.

The objective of this study was to assess the change in oral health-related quality of life following treatment with double crown-retained removable partial dentures (RPDs). Sixty RPDs in 54 patients (mean age: 65 years) were fabricated and retained with either galvanoformed telescopic secondary crowns (n = 30) or conical secondary crowns (n = 30). The Oral Health Impact Profile (OHIP) was assessed pretreatment and during 6- and 12-month follow-up appointments. Patient assessment of denture-satisfaction was also recorded on a Lickert-type scale. A decrease in the OHIP-sum score was significant after treatment for both groups, but not between the experimental groups. The denture assessment showed good values for both groups. Treatment with different double crown-retained RPDs improved oral health-related quality of life.

Purpose: This study investigated the possible relationship between the survival of complete crowns (CCs), 3-unit fixed dental prostheses (3uFDPs), and fixed dental prostheses (FDPs) versus gender and age at initial treatment over a period of 18 to 20 years in an undergraduate clinic. Materials and Methods: Complete treatment and follow-up records of 1,037 CCs (60.5% women/39.5% men; age range: 18 to 82 years), 134 3uFDPs (59.2% women/40.8% men; age range: 33.6 to 93.6 years), and 322 FDPs (62.1% women/37.9% men; age range: 33.6 to 94.2 years) were available for analysis. Failures of the fixed prosthetic restorations were defined as irreversible complications (finish line involved or loss of CCs, FDPs, or abutments). Results: The association between gender versus irreversible complications for the CCs (P = .481), 3uFDPs (P = .814), and FDPs (P = .410) groups was not statistically significant. The relationship between age versus irreversible complications for the fixed prosthetic restorations was statistically significant for all test groups. The patients with the failing restorations (66.2 years; mean range: 64.8 to 67.5 years) were 4.5 to 5.5 years older at initial treatment than the patients with the surviving restorations (61.3 years; mean range: 59.5 to 63.0 years). Conclusions: There was no relationship between gender and irreversible complications. There was a clear statistically significant association between age and irreversible complications. Receiver operating characteristic analysis for all study groups revealed that for age, no clear cutoff point exists with acceptable specificity and sensitivity

Purpose: This study was undertaken to investigate the chemical solubility and flexural strengths of 3 zirconia-based dental ceramics: In-Ceram Zirconia (IZ), In-Ceram 2000 YZ CUBES (YZ Zirconia) (Vita Zahnfabrik), and Cercon (Dentsply). A pressable lithium disilicate-reinforced glass ceramic (IPS Empress 2, Ivoclar Vivadent) was used as a control. Materials and Methods: Ten block specimens (12 × 6 × 4 mm) of each ceramic material were prepared for chemical solubility testing. Each specimen was refluxed in 4% acetic acid solution for 16 hours. The percentage loss of mass and the loss of mass per unit of surface area for each specimen were calculated. Ten bar-shaped (21 × 5 × 2 mm) and 10 disk-shaped (16 mm diameter, 1.2 mm thickness) specimens of each ceramic material were prepared and tested for uniaxial flexural strength (UFS) and biaxial flexural strength (BFS). X-ray diffraction analyses were conducted to determine the relative amount of the monoclinic phase of the as-sintered and fractured surfaces of the zirconia ceramics. Results: There were no significant differences among the ceramics in chemical solubility by percentage mass or mass/surface area. For UFS, YZ Zirconia (899 ± 109 MPa) > Cercon (458 ± 95 MPa) IZ (409 ± 60 MPa) > Empress 2 (252 ± 36 MPa). For BFS, YZ Zirconia (1,107 ± 116 MPa) > Cercon (927 ± 146 MPa) > IZ (523 ± 51 MPa) > Empress 2 (359 ± 43 MPa). The fractured YZ Zirconia surface contained approximately 5 times as much monoclinic phase compared to that of its intact surface. The fractured IZ and Cercon surfaces contained approximately twice as much monoclinic phase compared to those of intact surfaces. Conclusion: The ceramics tested all satisfied the chemical solubility allowance required of core ceramic material (type I, Class 1 or type II, Class 1) according to the International Organization for Standardization 6872:1995(E) specifications on dental ceramic. The zirconia-based ceramics possessed significantly higher flexural strengths than the control lithium disilicate ceramic. Their clinical application appears sufficiently promising for long-term clinical studies to be undertaken.

The aim of this study was to evaluate 4 veneer composites-Signum+EM, Gradia Enamel E3, Sinfony E3, and SR Adoro S1-in a standardized test at 2 different conditions. For each composite, 2 groups of specimens (added to cultures immediately after preparation [ie, fresh] or after 7 days of incubation in cell culture medium) were added to L-929 fibroblast cultures for 72 hours. All composites showed reduced cell numbers compared to glass controls. Fresh specimens of Signum+EM exhibited the least cytotoxicity, followed by Gradia Enamel E3 and Sinfony E3 and then SR Adoro S1. For specimens with 7-day incubation, 3 of the composites (Signum+EM, Sinfony E3, and Gradia Enamel E3) showed similarly low cytotoxicity, while cytotoxic results with SR Adoro S1 were significantly higher. With low in vitro toxicity values in conjunction with good mechanical properties, veneer composites appear to offer an interesting alternative for prosthetic rehabilitation.

Purpose: This study aimed to assess the prevalence of temporomandibular disorders (TMD) and associated variables among adolescents from 16 to 18 years of age in their senior year of high school in the city of Recife, Pernambuco, Brazil, in 2005. Materials and Methods: The studied variables were gender, self-esteem and nervous behavior, type of occlusion, and use of orthodontic appliances. In this cross-sectional study, the nonpatient population comprised 410 adolescents attending private and state schools. The data collection was conducted using 2 questionnaires, the first of which was used to evaluate the prevalence of TMD and the second to assess self-esteem. A clinical examination was conducted for the occlusion aspect of the evaluation. Results: The prevalence of TMD was 16.3% in the study group and there was no statistical difference between occlusions judged as normal or as malocclusions (P = .1148). There was a statistically significant association between students who had previously undergone orthodontic treatment and TMD (P = .0033, odds ratio: 3.08). The students classified in the low self-esteem group showed a significant increase in TMD (P = .0140). The group that classified themselves as nervous also showed an increase (P = .0034), with a higher prevalence also found in females (P = .0021). Conclusions: This study suggests that low self-esteem and gender may be more frequently related than dental factors to TMD in adolescents

The aim of this study was to determine the decision-making practices of a subset of North American prosthodontists. A survey was administered to assess practitioner views regarding the relative importance of practitioner, patient, and patient family beliefs and preferences during treatment planning of the edentulous patient. In responses to abstract questions, practitioners appeared to endorse a blending of patient and practitioner beliefs and preferences when treatment planning. However, in response to a question proposing a simulated clinical scenario, practitioners indicated they placed a greater emphasis on their own beliefs when choosing a treatment option.

Purpose: The purpose of this study was to retrospectively evaluate the clinical performance of bonded indirect resin composite onlays for the treatment of painful, cracked teeth over a 6-year period. Materials and Methods: Forty-three posterior teeth diagnosed as having a crack were selected in the restorative department of the University of Genoa. Inclusion criteria were sensitivity to biting and cold and a clinically visible crack. Direct composite buildup after removal of the existing restoration was performed before definitive cavity preparation. All composite onlay restorations were cemented with an adhesive technique using a 3-step total etch system and a dual-cure composite cement. Patients were interviewed and clinically examined at 1 week, 4 weeks, and every 6 months. Results: The effectiveness of bonded onlay restorations was evaluated for a mean observation time of 4.78 years. At 1 week, 38 (88.37%) restored teeth were free of pain, 3 (6.98%) still had sensitivity to cold, and 2 (4.65%) still had sensitivity to cold and chewing. At 4 weeks, 40 (93.02%) teeth were free of pain, 2 (4.65%) still had sensitivity to cold and chewing, and 1 (2.32%) needed endodontic treatment. Two other teeth (4.65%) also needed endodontic treatment, the first after 2 months and the second after 5 months. During the evaluation period, 3 restorations (6.98%) failed, and upon clinical examination, 40 (93.02%) teeth were free of symptoms with a 6-year survival rate of 93.02% (life table analysis). Conclusions: Bonded indirect resin composite onlays can be successful in treating painful, cracked teeth. From the findings of this study, it appears that cuspal protection should be incorporated into the design of coronal restorations

Purpose: The aim of this retrospective study was to present the results of implants and natural teeth used as combined abutments to support maxillary telescopic prostheses. Materials and Methods: Between 1997 and 2004, 22 patients with residual maxillary teeth underwent prosthodontic rehabilitation with supplementary implant placement of implant-tooth-supported telescopic prostheses. A total of 60 supplementary implants (mean: 2.9 implants; SD: 1.6; range: 1 to 5 per patient) were placed in strategic position and connected with 48 natural abutment teeth (mean: 2.2 teeth; SD: 0.9; range: 1 to 4 per patient) using telescopic crowns. The follow-up registration included implant and natural tooth survival rates and peri-implant and periodontal parameters, along with prosthodontic maintenance. Natural tooth abutments were additionally followed to compare their periodontal parameters at baseline to the follow-up examination. Results: After a mean of 38 months (12 to 108 months) no implants or natural tooth abutments were lost (survival rate: 100%). There was no fracture, endodontic treatment, loss, or intrusion of natural teeth used for telescopic abutments. Implant abutments showed high stability and excellent peri-implant soft tissue conditions. Natural tooth abutments used for double crowns also showed uneventful progress. A low rate of prosthodontic maintenance was seen, with implant screw abutment loosening as the most severe complication (3 of 60 implants; 5%). Conclusions: On the basis of this retrospective clinical review, the following conclusions were drawn: (1) successful function over a prolonged period and a minor complication rate of implant-tooth-supported telescopic maxillary dentures may be anticipated, and (2) the great variety of treatment modalities offered by tooth-implant support for telescopic prostheses appears to be useful as a treatment option for the maxilla in elderly patients

The aim of this study was to evaluate dynamic micromotion at the implant-abutment interface for 3 different implant neck designs. Five samples each from 3 implant types with different neck designs were subjected to 1 x 10⁶ cycles under simulated oral conditions. Load magnitudes varied from 10 to 250 N at 15 Hz. The results revealed a significant main effect for type of implant (P < .0001). The main effect for level of cycles proved to be nonsignificant (P = .9999), as did the interaction between type of implant and level of cycles (P = .9989). Differences in neck design among the 3 implant types resulted in differences in micromotion at the implant-abutment interface under simulated oral conditions.

Purpose: To analyze the prevalence and magnitude of tooth movements adjacent to single-implant crowns in a long-term study, and to discuss these changes in relation to changes in cephalometric measurements of a reference group after 10 years. Materials and Methods: Twenty-five of an original group of 39 patients, consecu-tively restored with single-implant crowns in the anterior maxilla, were included. The mean age was 25.4 years (SD: 10.0) at inclusion. Clinical photographs were taken at implant crown placement and at the final examination an average of 15.9 years (SD: 0.74) later. The reference group comprised 134 dental students with a mean age of 22.9 years (SD: 1.20) at inclusion. Cephalograms and study casts were made at inclusion and after 10 years. Study casts were also made after 20 years (n = 61). Tooth movements were assessed adjacent to the implant crowns according to a clinical index. For the reference group, cephalometric measurements were performed for anterior and posterior face height and gonion and nasion-sella line/mandibular line (NSL/ML) angles. Vertical overbite measurements were collected from the study casts. Results: Altogether, 28 implant crowns were included in the test group. Male patients presented a clinically stable situation without any signs of vertical tooth movement adjacent to the single-implant restorations in 11 of 20 implant sites, compared to none in female patients (P < .05). With regard to horizontal tooth movements, 55% of the sites showed palatal tooth movements, which were relatively more common in females. Both males and females presented a significant average increase of anterior and posterior face height (P < .05), but only females presented a significant increase of the NSL/ML angle. Average vertical overbite was basically stable for 20 years, but individual variations were obvious. Conclusions: A possible relationship between significantly higher incidence of tooth movements adjacent to implants in females in the study group and significantly greater increase of anterior face height and posterior rotation of the mandible in the female reference group was observed

Purpose: This study aimed to assess the long-term survival rates of polyethylene fiber-reinforced posts and cores used in endodontically treated teeth over a 97-month period. Materials and Methods: Sixty-nine patients from a private dental office who underwent endodontic treatment with coronoradicular fiber-reinforced restorations were selected and invited for evaluation. All teeth were restored with the same high-molecular-weight polyethylene fiber (Ribbond, Ribbond Inc) and resin composite cement (Enforce, Dentsply) post-and-core system by a single operator and then prepared and restored with complete cast crowns or direct resin composite. Survival functions of restorations were analyzed with Kaplan-Meier and log-rank tests (a = .05) and displayed according to the variable tooth location and material of the definitive restoration. Results: Four posts fractured among the 36 anterior restorations evaluated, and 2 posts fractured among the 73 posterior restorations. The mean overall survival estimate was 90.2 (± 3.7) months (95% CI: 82.8-97.5). There were no differences between survival functions regarding tooth location or type of restorative material as variables (P > .05). Conclusions: The results suggest that polyethylene fiber-reinforced posts with composite cores may be recommended for clinical use. Restorations evaluated in this study presented high survival rates after the 97-month follow-up period.

The aim of this study was to investigate the proportion of 3 Neil's classifications of lateral throat forms and the difference in the length of the lateral throat form between the dentures and the patient's actual anatomy. The classification of lateral throat form was determined by the patient's functional movements, and an implant depth gauge was used to measure the length of the lateral throat form in the patient's mouth and compare it to that of the dentures. One hundred mandibular edentulous patients were measured. The proportion of Neil's Class I lateral throat form was 70%, the proportion of Class II was 25%, and the proportion of Class III was 5%. The mean difference between the actual lateral throat forms and the dentures was 6.7 ± 2.9 mm at the anterior point of measurement (from the anterior part of the retromolar pad to the mouth floor) and 10.0 ± 3.7 mm at the posterior point (from the middle of the retromolar pad to the mouth floor). The difference in length between the ridge height of the mouth and the denture was statistically significant (P < .001).

Chewing ability and dental status were assessed in 2 Swedish counties via questionnaires sent in 1992 and 2002 to all subjects born in 1942. Those who answered both questionnaires-at ages 50 and 60-were included in the study (n = 5,008). The proportion of those who reported chewing ability as very good decreased from 75% to 66% during the 10-year follow-up. Approximately 80% of complete denture wearers considered their chewing ability to be good. Chewing ability was reported to be worse at age 60 than at age 50, although there was only a minor impairment in dental status.