Nonparametric estimation in an "illness-death" model when all transition times are interval censored.

We develop nonparametric maximum likelihood estimation for the parameters of an irreversible Markov chain on states {0,1,2} from the observations with interval censored times of 0 → 1, 0 → 2 and 1 → 2 transitions. The distinguishing aspect of the data is that, in addition to all transition times being interval censored, the times of two events (0 → 1 and 1 → 2 transitions) can be censored into the same interval. This development was motivated by a common data structure in oral health research, here specifically illustrated by the data from a prospective cohort study on the longevity of dental veneers. Using the self-consistency algorithm we obtain the maximum likelihood estimators of the cumulative incidences of the times to events 1 and 2 and of the intensity of the 1 → 2 transition. This work generalizes previous results on the estimation in an "illness-death" model from interval censored observations.

Survival rates for porcelain laminate veneers with special reference to the effect of preparation in dentin: a literature review.

UNLABELLED: The porcelain laminate veneer is an elective restoration, often placed in the absence of disease for purely esthetic reasons. As such, it would appear desirable that the success rate of the technique was 100%. It is therefore the purpose of this paper to review the literature on porcelain laminate veneer survival by searching dental databases containing clinical trials of porcelain veneer restorations. References of selected trials were also screened to identify relevant studies. Each paper that was included was examined to ascertain if preparation into dentin affected survival. A total of 24 papers were included in the review. It was concluded that survival rates of porcelain laminate veneers are rarely 100%, and there is reasonable evidence indicating that a veneer preparation into dentin adversely affects survival. CLINICAL RELEVANCE: A review of the literature has indicated that porcelain laminate veneer survival is rarely 100%. Accordingly, patients should be made aware of this before embarking on this elective restorative technique. Clinicians should also be aware that the ideal preparation for porcelain veneers remains within enamel.

[Assessment prevalence and risk factors of aesthetic defects dens and need veneers in a population Georgia].

PURPOSE: definition risk - factors of aesthetic defects of dens and need veneers. The work is fulfilled on the basis of research 330 persons age from 14 till 70 years from a common population of Tbilisi. Phylum of research - case - control of Criterion of incorporation: the patients entered clinic per 2005-2009, Criterion of exception: general diseases, Diabetes, autoimmune diseases, serious forms parodontosis, called by somatopathies. Statistical Analysis spent with the help of the package of statistical programs SPSS 11.5 Is placed, that the relative chance of need veneers is defined by the following factors: smoking - OR=1.82 (95%CI=1.13-12.37); pathologies gastrointestinal of a path - OR=1.94 (95%CI=1.22-14.26); the locuses of a focal infection contamination - OR=65.57 (95%CI=8.80-76.22); the mechanical factor - OR=2.23 (95%CI=1.27-58.95); medicamental treatment - OR=2.14 (95%CI1.34-24.56); feeding mainly by carbohydrates - OR=2.89 (95%C=I.51-13.15); the often use sweet - OR=1.87 (95%CI=1.07-9.85); often use of coffee OR=1.75 (95%CI=1.10-12.51); distal an occlusion - OR =2.26 (95%CI=1.09-18.68); - subcompensated caries - OR=2.04 (95%CI1.28-23.48); a ulitis - OR=1.62 (95%CI1.02-19.20); complications after previous veneer: particulate or complete chip of a seal - OR=34.12 (95%CI7.98-52.11); discoloration a seal - OR=80.67 (95%CI19.15-509.48); appearance line of demarcation - OR=95.23 (95%CI12.86-714.61); recurrent a caries - OR=25.75 (95%CI=7.69-39.87); Ulitis - OR=11.22 (95%CI=3.22-68.99); exhibitings of a pathological microflora - OR=123.16 (95%CI=16.68-726.40).

[Correlations complications after cosmetic veneer treatment with initial parameters of oral cavity].

The aim of the study was to define interrelations between complications after veneer treatment with initial parameters of an oral cavity, state of an organism, social and biological factors. 65 patients with veneers treated between 2005 and 2009 at Margvelashvili Dental Clinic (Tbilisi) were investigated. Correlation analysis on Spearmen was spent with application of the package statistical programs SPSS 11.5. Chip of veneers finds out significant positive correlation with the following factors: a crossbite - r=0.2543, p<0.0409; decompensative caries - r=0.3189, p<0.0096; exhibiting of a pathological microflora - r=0.2879, p<0.0163; discoloration - patient with age 41-60 y. - r=0.3877, p<0.0014; focal infection contamination - r=0.2599, p<0.0366; often use of coffee - r=0.2819, p<0.0229; ulitis up to veneer - r=0.2444, p<0.0498; appearance line of demarcation - with the mechanical factor - r=0.3479, p<0.0045; use of synthetic fluids, - r=0.3823, p<0.0017; recurrence caries - with gastro-intestinal pathologies r=0.2924, p<0.0181; of a focal infection contamination - r=0.2756, p<0.0263; by feeding priority by carbohydrates - r=0.2324, p<0.0625; decompensate caries - r=0.2583, p<0.0377; Exhibiting of a pathological microflora - among males - r=0.2772, p<0.0254; by smoking - r=0.3227, p<0.0087; gastro-intestinal pathologies - r=0.2365, p<0.0579; by endocrine diseases - r=0.2546, p<0.0407; by focal infection contamination - r=0.5416, p<0.0000; decompensate caries - r= 0.2530, p<0.0420; by an ulitis - r=0.4551, p<0.0001; by a hygienic index - r=0.4611; p<0.0001; periodontal index - r=0.4611, p<0.0001; PMA index - r=0.3529, p<0.0039. The correlation circuit of the factors of complications after veneers will help the practical stomatologists with realization of purposeful prophylaxis.

Ten-year outcome of porcelain laminate veneers placed within the general dental services in England and Wales.

AIM: It is the aim of this paper to consider the factors associated with the need for re-intervention on teeth restored with porcelain veneers. METHODS: A data set was established consisting of adult patients (18 years or older) whose restoration records contained the placement of one or more porcelain laminate veneers. For each tooth treated with a porcelain veneer, the subsequent history of intervention on that tooth was consulted, and the next date of intervention, if any could be found in the extended data set, was obtained. Thus a data set was created of porcelain veneers which have been placed, with their dates of placement and their dates, if any, of re-intervention. RESULTS: Data for over 80,000 different adult patients were analysed, of whom 46% were male and 54% female. A total of 2562 porcelain veneer restoration occasions in 1177 patients were obtained from the data over a period of 11 years. Factors which were found to influence the survival of porcelain veneers include patient gender, patient age, changing dentist, patient's treatment need, patient charge-paying status and geographical area. CONCLUSIONS: While dentist factors do not appear to play a part, a variety of patient factors have been found to influence veneer survival to re-intervention. Overall, 53% of porcelain veneers in the study survived without re-intervention at 10 years.

Analysis of an administrative database of indirect restorations over 11 years.

AIM: This paper describes the database used to assess the survival of indirect restorations and presents general data on survival of these restorations. METHODS: Data, based on the complete attendance and treatment history, over the 11 years from 1991 to 2001, of a statistically representative sample of 23,165 General Dental Services' (GDS) patients in England and Wales, all of whom received at least one indirect restoration during the observation period, have been analysed. The patients on the database received a total of 36,397 courses of treatment, and there were 52,481 indirect restorations placed. The method of analysis involved the estimation of the probability that the patient will eventually return, given an interval without attending, by analysing the observed patterns of re-attendance. This estimated probability of re-attendance was then used to modify the standard Kaplan-Meier procedure to produce realistic estimates of the hazard of re-intervention. RESULTS: Overall, 75% of indirect restorations remained without re-intervention after 5 years, and 61% after 10. Crowns outperformed other types of indirect restoration. Multi-surface metal inlays, by contrast, had a median interval to re-intervention of less than 8 years. CONCLUSIONS: The times to re-intervention for different types of indirect restoration have been successfully estimated and crowns shown to outperform veneers and inlays.

Veneered zirconia inlay-retained fixed dental prostheses: 10-Year results from a prospective clinical study.

OBJECTIVE: The purpose of this study was to evaluate the 10-year clinical performance of zirconia-based inlay-retained fixed dental prostheses (IRFDP). METHODS: For replacement of a molar in 27 patients, 30 IRFDP were luted by use of different cements, Panavia F (Kuraray Europe GmbH) or Multilink Automix (Ivoclar Vivadent GmbH), with use of inlay/inlay, inlay/full-crown, or inlay/partial-crown retainers for anchorage. Frameworks were milled from yttria-stabilized zirconia (IPS e.maxZirCAD; Ivoclar Vivadent GmbH) and fully veneered with pressable ceramic (IPS e.max ZirPress; Ivoclar Vivadent GmbH). Before luting, the IRFDP were silica-coated (Rocatec; 3M Espe) and silanized (Monobond S; Ivoclar Vivadent GmbH). Complications (for example, chipping or delamination of the veneering ceramic, debonding, secondary caries, endodontic treatment, and abutment tooth fracture) and failure were reported, by use of standardized report forms, 2 weeks, 6 months, and 1, 2, and 10 years after cementation. Statistical analysis included Kaplan-Meier survival and success (complication-free survival) and Cox regression analysis (α=0.05 for all). RESULTS: During the 10-year observation period, the complications most often observed were chipping of the veneer and debonding. Twenty-five restorations failed and one participant dropped out. Cumulative 10-year survival and success were 12.1% and 0%, respectively. The design of the retainer, use of a dental dam, choice of cement, and location in the dental arch had no statistically significant effect on the occurrence of complications. CONCLUSIONS: Use of fully veneered zirconia-based IRFDP with this technique cannot be recommended. CLINICAL SIGNIFICANCE: A large incidence of complications and poor survival were observed for fully veneered zirconia-based IRFDP, revealing an urgent need for further design improvements for this type of restoration. This, again, emphasizes the need for testing of new restoration designs in clinical trials before implementation in general dental practice.

Zirconia-based versus metal-based single crowns veneered with overpressing ceramic for restoration of posterior endodontically treated teeth: 5-year results of a randomized controlled clinical study.

OBJECTIVES: The aim of this 5-year randomized controlled trial was to compare the longevity and clinical behavior of single posterior crowns made with pressable ceramic on zirconia and on metal frameworks, and if failures occur, to delineate the contributing factors. METHODS: 72 patients, who needed the covering of at least a molar and/or premolar, were included in the study. All teeth were endodontically treated, with absence of periapical lesion or active periodontitis. Ninety single crowns were made with zirconia or metal framework and covered with pressable veneering ceramics. Two independent examiners assessed the survival of restorations at 6 months, 1-4 and 5 years after restoration placement including periapical radiographs, intraoral photographs, and USPHS modified criteria. The statistical analyses were performed with the Kaplan-Meier method. RESULTS: One core fracture occurred in Zircad/Zirpress crowns and one metal ceramic crown was lost for root fracture. Chipping fracture of the veneering ceramic was detected in 2 metal-ceramic crowns and in 3 zirconia-based crowns. The Estimate Cumulative Survival (ECS) and the Estimate Cumulative Success (ECSs) with standard deviation (SE) were respectively 97,73±2,19 and 92,64±4,14 for zirconia-based crowns whereas 97,44±2,39 and 91,11±4,27 for porcelain fused to metal crowns. CONCLUSIONS: The present randomized controlled trial shows that the survival of zirconia-based and metal-based single crowns is similar over a follow-up period of 5 years. No significant differences in esthetic, functional and biological outcomes were demonstrated between the two groups. The main failure mode was the chipping fracture of the veneering ceramic in both materials. Study number on ClinicalTrial.gov NCT02758457. CLINICAL SIGNIFICANCE: According to the results of this clinical study, zirconia-based rehabilitations with overpressing veneering technique represent a valid alternative to metal-based for posterior single crown restorations.

Study of the colors and retention of over-the-counter cosmetic veneers.

The purpose of this study was to observe the tooth colors and retention of a cosmetic veneer Fiche Pearl On containing shellac and five experimental formulations containing benzoin gum and ethyl cellulose. Tooth color was measured with a spectrophotometer before and after application of the veneers to the buccal or labial surface of experimental teeth. Through both in vitro and in vivo studies, the retention rates of veneers were assessed. In terms of color difference (deltaE*ab) between before and after veneer application, it ranged from 4.3 (Fiche Pearl On) to 15.0 (experimental formulation White Plus). In terms of retention rate, in vitro test found the retention rate of experimental formulation White Plus was significantly higher than that of Fiche Pearl On. In in vivo test where subjects were permitted to drink water and tea, it was found that the retention rate after two hours ranged from 94.0 to 98.5%. In conclusion, teeth applied with the experimental cosmetic veneer formulations showed better color and retention than teeth with Fiche.

Survival analysis of complete veneer crowns vs. multisurface restorations: a dental school patient population.

The purpose of this study was to compare the longevity of crowns versus large multisurface restorations in posterior teeth. The investigation used the treatment database at Virginia Commonwealth University School of Dentistry. The inclusion criteria for the final data set used for analysis were: only one restored tooth per patient, premolars with three or more restored surfaces, molars with four or more restored surfaces, molars and premolars restored with complete veneer metal crowns, or crowns veneered with metal and porcelain. The Kaplan-Meier approach was used to visualize the survival curves, and the Cox proportional hazards model was used for analysis of predictor variables. The investigation indicates crowns survive longer than large restorations and premolar restorations survive longer than molar restorations. The median survival for crowns exceeded 16.6 years, with the median survival of premolar restorations being 4.4 years and molar restorations 1.3 years. An interaction between age and treatment was discovered, with overall survival decreasing as patient age increases. The doctor supervising the treatment also affected survival with treatment supervised by specialists lasting longer than treatment supervised by nonspecialists.

Dental technicians' experiences with all-ceramic extra-coronal restorations.

The aim of this study was to identify the dental technicians' experiences with extra-coronal all-ceramic restorations. A questionnaire was mailed to all laboratories registered in The Norwegian Association of Dental Laboratory Owners (n=186). The response was 149 (80%). All-ceramic restorations were produced by 93 (62%) of the responding laboratories. A few of these (1 7%) produced the majority (67%) of the restorations. The dental technicians reported low rates of remakes (median 2%) for all-ceramic restorations. The low production and the limited number of laboratories that perform this work show that there is room for extended training and more expertise in this field.

Direct anterior composite veneers in vital and non-vital teeth: a retrospective clinical evaluation.

OBJECTIVES: This retrospective, longitudinal clinical study investigated the performance of direct veneers using different composites (microfilled×universal) in vital or non-vital anterior teeth. METHODS: Records from 86 patients were retrieved from a Dental School clinic, comprising 196 direct veneers to be evaluated. The FDI criteria were used to assess the clinical evaluation. The survival analysis was done using Kaplan-Meier method and Log-Rank test. The multivariate Cox regression with shared frailty was used to investigate the factors associated with failure. RESULTS: A total of 196 veneers were evaluated, with 39 failures. The mean time of service for the veneers was 3.5 years, with a general survival rate of 80.1%. In the qualitative evaluation of the restorations, microfilled composite showed slighty better esthetics. The annual failure rates (AFR) were 4.9% for veneers in vital teeth and 9.8% for non-vital teeth with statistical significance (p=0.009). For microfilled and universal veneers the respective AFRs were 6.0% and 6.2% (p>0.05). Veneers made in non-vital teeth had a higher risk of failure over time compared to those made in vital teeth (HR 2.78; 95% CI 1.02-7.56), but the type of material was not a significant factor (p=0.991). The main reason for failure was fracture of the veneer. CONCLUSION: Direct composite veneers showed a satisfactory clinical performance. Veneers performed in vital teeth showed a better performance than those placed in non-vital teeth. No difference in the survival rate for different composites was found, although microfilled composites showed a slightly better esthetic appearance. CLINICAL SIGNIFICANCE: Direct composite veneers show good results in esthetic dentistry nowadays. Composite veneers in vital teeth have a lower risk of failure than those in non-vital teeth.

A randomized controlled clinical trial of 3-unit posterior zirconia-ceramic fixed dental prostheses (FDP) with layered or pressed veneering ceramics: 3-year results.

OBJECTIVES: The aim of the present pilot study was to test whether or not posterior zirconia-ceramic fixed dental prostheses (FDPs) with pressed veneering ceramic exhibit less chipping than FDPs with layered veneering ceramics. METHODS: Forty patients (13 female, 27 male; mean age 54 years (range 26.1-80.7 years) in need of one maxillary or mandibular three-unit FDP in the second premolar or molar region were recruited and treated at two separate centers at the University of Zurich according to the same study protocol. The frameworks were made out of zirconia using a CAD/CAM system (Cerec Sirona, Bensheim, Germany). The patients were randomly assigned to either the test group (zirconia frameworks veneered with pressed ceramic; IPS e.max ZirPress, Ivoclar Vivadent AG, Schaan, Liechtenstein; n=20) or the control group (layered veneering ceramic; IPS e.max Ceram, Ivoclar Vivadent AG, Schaan, Liechtenstein; n=20). All FDPs were adhesively cemented and evaluated at baseline (i.e., cementation), at 6 months and at 1 and 3 years of clinical service. The survival of the reconstruction was recorded. The technical outcome was assessed using modified United States Public Health Services (USPHS) criteria. The biologic parameters analyzed at abutment teeth and analogous non-restored teeth included probing pocket depth (PPD), plaque control record (PCR), bleeding on probing (BOP), and tooth vitality (CO2). Data was descriptively analyzed and survival was calculated using Kaplan-Meier statistics. RESULTS: 36 patients (25 female, 11 male; mean age 52.3 years) with 18 test and 18 control FDPs were examined after a mean follow-up of 36 months (95% CI: 32.6-39.1 months). Comparison of groups was done by Crosstabulation showing even distribution of the respective restored teeth amidst the groups. Survival rate was 100% for both test and control FDPs. Chipping of the veneering ceramic tended to occur more frequently in test (n=8; 40%) than in control (n=4; 20%) FDPs, albeit not significantly (p=0.3). No further differences of the technical outcomes of test and control FDPs occurred.In both test and control group healthy conditions and no difference of the biologic parameters at the abutment and un-restored teeth was found. CONCLUSION: Zirconia FDPs with pressed and layered veneering ceramics exhibited similar outcomes at 3 years. A trend to more chipping of the pressed veneering ceramic, however, was observed. CLINICAL SIGNIFICANCE: Posterior restorations with zirconia frameworks are a viable treatment method. When restoring posterior teeth with all-ceramic restorations, care providers should be aware of the higher rate of chipping compared to the published data on conventional metal-ceramic restorations.

Cosmetic dental treatment in an adult Dutch population.

In 1992 a follow-up to the Dutch national dental survey of 1986 (DNDS) was performed. The main objective was to analyse changes in oral self care, dental attendance, and oral health status. A postal questionnaire was used: 936 persons (44 per cent response) participated in the study. This paper will focus on the results concerning cosmetic dental treatment. Stepwise regression analyses were used to study the effect of dental and social variables. Relative risks (RR) were computed to clarify the effect of these variables. Of the group of respondents, 90 persons reported having been treated with veneers on their anterior teeth. The variables indicating cosmetic dental treatment needs established during the DNDS clinical dental examination, showed a statistically significant influence. 'Objective need': RR = 2.6; 'Subjective need': RR = 2.1. Out of 877 respondents with restorations present in 1986, 19 per cent reported having one or more of them replaced by composite or porcelain. Four variables were found to have a statistically significant influence: 'Subjective need': RR = 1.7; 'Number of filled tooth surfaces': RR = 1.6; 'Number of decayed tooth surfaces': RR = 1.4; and 'Frequency of toothbrushing': RR = 1.6. Whereas the dentists' opinions had the most influence on having veneer treatments, the patients' opinions had more influence on having amalgam restorations replaced with composite or porcelain.

Factors influencing long-term restoration survival in three private dental practices in Adelaide.

Very little is known of dentist and patient factors which may influence the survival or longevity of dental restorative materials placed in private practices. The present retrospective study investigated during 1992 the effects of six factors on the long-term survivals of five types of restorations placed by 20 male dentists in 100 adult patients, at 3 selected Adelaide dental practices. There were no significant effects on restoration survival from change, of dentist, and generally only one or two types of restorations had their survivals influenced significantly either by dental practice location, or by patient age, frequency of patient attendance, experience of dentist, and whether or not the restorations were replacements during the study period. Restoration survival was not influenced significantly by whether, or not, any replacements were made by the dentist who placed the initial restorations. The median survival times for amalgams were 22.52 years, resin composites 16.72 years, castings 13.75 years, and crowns an estimated 26 years. For glass-ionomers, 75 per cent were still present at 11.25 years.

The esthetic correction of anterior dental mal-alignment conventional vs. instant (restorative) orthodontics.

Creating a flow sheet may assist in the decision whether to use conventional orthodontics and what the limitations of treating the patient will be if treatment is performed without any orthodontics. The decision process can be viewed as a series of questions, and depending upon the answer to the questions, the practitioner and patient can decide on whether to involve orthodontics or not. Questions can create a framework to help separate the patients who would benefit from orthodontic intervention from those we all enjoy treating who can be managed with purely restorative care.

[Meta-analysis of anterior veneer restorations in clinical studies]. / Een systematisch literatuuroverzicht van klinisch onderzoek naar veneerfrontrestauraties.

A systematic review was used to make an inventory of clinical studies on veneer restorations. Based on a protocol articles were selected that were subsequently assessed for their quality. With 'failure of the restoration' as a study outcome, survival data of the restorations were generated from the selected studies and a mean survival result was composed. Porcelain veneer restorations showed an acceptable 3-year survival, which was favourable to the 3-year survival of preformed acrylic veneers. The quality assessment expressed that reports on clinical studies should be more standardised in order to make it easier to compare the results of different studies.

Oral health status and treatment need among institutionalised hearing-impaired and blind children and young adults in Udaipur, India. A comparative study.

AIM: The aim of this study was to assess and compare the oral health status and the treatment needs of the institutionalised hearing-impaired and blind children and young adults in the city of Udaipur, Rajasthan, India. METHODS: A descriptive cross-sectional study was conducted among 498 institutionalised hearing-impaired and blind people, aged 4 to 23 years, in the city of Udaipur, Rajasthan. The World Health Organization oral health assessment basic methods and form (1997) were used for data collection. Clinical examinations were carried out in the institute's medical room or classroom by single examiner with the aid of a mouth mirror, explorer and Community Periodontal Index (CPI) probe under adequate natural light (Type III examination). The resulting data were entered into statistical software and analysed by applying the chi-square test, ANOVA, t-test and stepwise multiple linear regression analysis. RESULTS: The total mean DMFT (decayed-missing-filled teeth) and mean dft scores were 1.77 and 0.27 respectively. The largest component of DMFT was the D, with a mean of 1.49. The F component of 0.08 was very low. Mean DMFT/dft was greater among hearing-impaired than among blind subjects. Overall, 159 (32%) were periodontally healthy (CPI=0), 162 (32%) had shallow pockets (CPI=3) and 36 (7%) had deeper pockets (CPI=4). A higher percentage of the blind (87; 43%) than the hearing-impaired (72; 24%) subjects were periodontally healthy (CPI score=0). One-surface fillings were the most commonly provided form of past treatment. CONCLUSION: The findings in this study highlight the lack of dental treatment for this group. Overall oral health status was poorer in the hearing-impaired than in the blind subjects.

Contemporary dental practice in the UK in 2008: indirect restorations and fixed prosthodontics.

OBJECTIVES: To investigate, by postal questionnaire, various aspects of primary dental care provision in the United Kingdom. Additionally, to compare the results of this survey with a similar survey completed four years previously. METHODS: A questionnaire containing 89 questions was sent to 1,000 general dental practitioners selected at random from databases of practitioners throughout the United Kingdom. Non-responders were sent another questionnaire after a period of four weeks had elapsed. RESULTS: Overall a response rate of 66.2% was achieved. Amalgam was the preferred material for the core build up of vital teeth for 65% of the respondents. Dentine pins were still being used by practitioners, with stainless steel pins being preferred by 34% of respondents. 39.7% of dentists that had graduated between 0-10 years previously reported using no pins. Indirect posts were still used most widely, by 55% of the practitioners in the study, with increasing use of fibre posts noted (34%). Addition cured silicone impression materials were still the most frequently used impression material (71%) with reduced use (10%) of condensation cured silicone impression materials recorded. Glass ionomer luting cements (48%) and zinc phosphate (28%) were the most commonly used luting cements. CONCLUSIONS: Within the limitations of this study, the following conclusions can be drawn: amalgam is still the preferred material for the core build-up of vital teeth; dentine pins are still used widely, but not by younger practitioners; fibre posts are being increasingly used by practitioners; addition cured silicone is still the most widely used impression material; traditional glass ionomer cements are still the most widely used luting cements; veneers are still the preferred indirect restoration for restoring anterior teeth; and CAD/CAM systems are increasingly being used by practitioners.