A retrospective clinical evaluation of extensive tooth-supported fixed dental prostheses after 10 years

Up to 10 years clinical performance of zirconia ceramic and metal-ceramic fixed partial dentures: A retrospective study

STATEMENT OF PROBLEM

Completely veneered zirconia ceramic (ZC) fixed partial dentures (FPDs) have been reported to have a higher incidence of ceramic chipping than the standard metal-ceramic FPDs. However, data from comparative long-term studies are sparse.

PURPOSE

The purpose of this retrospective study was to compare the long-term survival, chipping-free survival, and success of ceramic-veneered high noble metal alloy (HN), base metal alloy (cobalt-chromium alloy) (CC), and ZC FPDs and to isolate risk factors for the incidence of failure, veneer chipping, and overall complications.

MATERIAL AND METHODS

Data from 289 study participants (58.7% women; mean age, 57.97 ±11.51 years) provided with a total of 400 FPDs comprising 197 (49.3%) HN FPDs, 121 (30.3%) CC FPDs, and 82 (20.5%) ZC FPDs fabricated from presintered 3 mol% yttria-stabilized zirconia (mean time of service, 6.85 ±3.25 years) were evaluated. Of these, 278 (69.5%) FPDs were provided by dentists and 122 (30.5%) by dental students. Five- and 10-year survival, chipping-free survival, and success rates were calculated using the Kaplan-Meier method and compared with the log-rank test. Risk factors were assessed using Cox regression analysis. The study was exploratory, so all P values were considered exploratory and descriptive.

RESULTS

The 5- and 10-year survival rates were 94.7% and 77.8% for HN, 93.7% and 81.2% for CC, and 92.9% and 53.3% for ZC FPDs, respectively, indicating no clear difference in survival among the framework materials. The 5- and 10-year chipping-free rates were 94.1% and 82.8% for HN, 96.1% and 78.9% for CC, and 82.6% and 62.2% for ZC FPDs, respectively, indicating a difference between HN and ZC, and CC and ZC restorations. The 5- and 10-year success rates were 83.7% and 55.3% for HN, 86.5% and 51.4% for CC, and 68.9% and 30.2% for ZC FPDs, respectively, indicating a difference between HN and ZC, and CC and ZC restorations. The Cox regression model indicated framework material as an influencing risk factor for success, and this influence persisted when chipping was investigated. Compared with zirconia, the use of a metal alloy reduced the risk of chipping or the occurrence of complications by up to one-third.

CONCLUSIONS

All FPDs showed high 5-year survival rates and acceptable 10-year survival rates with no strong differences among the materials. Higher success and chipping-free rates were observed for both HN and CC restorations compared with ZC restorations. Metal frameworks had a lower risk for complications or veneer chipping than zirconia frameworks.

Evaluation and Comparison of Five-Year Survival of Tooth-Supported Porcelain Fused to Metal and All-Ceramic Multiple Unit Fixed Prostheses: A Systematic Review

The prosthesis must have good survival despite being functional for at least 5-10 years. This makes sure that the replacement of missing teeth does not become a repeated expense. Of 579 identified articles, 15 met the inclusion criteria for systematic review. Missing teeth replacement materials are divided into two groups: porcelain fused to metal and all ceramics. Data related to survival rates as well as the most common mode of failure is observed from both groups. It was observed that porcelain fused to metal prostheses had an approximately 99.5% survival rate and an approximately 92% survival rate for all-ceramic tooth-supported prostheses after five years of insertion. Porcelain-fused-to-metal (PFM) prostheses had a better survival rate after five years of insertion as compared to all-ceramic prostheses. Porcelain fused to metal should be the treatment of choice for dentists and patients when missing teeth need to be fixed.

Long-term retrospective clinical study of tooth-supported fixed partial dentures: A multifactorial analysis

PURPOSE

To assess the influence of several factors on the survival of tooth-supported fixed partial dentures (FPDs) with vital and non-vital abutments.

MATERIALS AND METHODS

The present retrospective cohort study was based on the records of patients treated with 3-to-7-unit tooth-supported FPDs with a minimum follow-up time of 6 months after prosthesis delivery. Cumulative survival rate (CSR) was calculated over the maximum follow-up period. Cox regression models were used to evaluate the association between the clinical covariates and prosthesis failure.

RESULTS

A total of 331 FPDs in 229 patients were included. The CSRs were 90.1% and 77.6% after 5 and 10 years and 67.9% and 52.1% after 15 and 20 years, respectively. Tooth-supported FPD failure was more prevalent within the first years of prosthesis delivery. Loss of one or more abutment teeth and loss of prosthesis retention were the main reasons for failure. Smoking and type of prosthesis material significantly influenced the survival of FPDs. Abutment vitality, position of the non-vital abutment, or prosthesis length did not show any significant influence on the occurrence of prosthesis failure.

CONCLUSION

Smoking and the type of prosthesis material are suggested to contribute to an increased rate of FPD failure irrespective of abutment vitality.

The Impact of Sintering Technology and Milling Technology on Fitting Titanium Crowns to Abutment Teeth-In Vitro Studies

INTRODUCTION

The aim of the study is to evaluate the marginal and internal fit of titanium alloy (Ti6Al4V) crowns using the Selective Laser Melting (SLM) method and CAD/CAM milling.

MATERIALS AND METHODS

The research materials are abutment teeth and prosthetic crowns. The method is based on scanning the abutments and the interior of the substructures, creating their 3D models, using the program for comparison, and determining error maps of fitting crowns to the reference models, in the form of positive and negative deviations. Adding the deviations gives information about the tightness of the crowns. The Shapiro-Wilk test and the one-way ANOVA analysis were performed. The level of significance was p = 0.05.

RESULTS

The crowns made in SLM, a slightly better internal fit was found than for milled crowns, as well as a comparable marginal fit. The mean deviations for the sintering were the values [mm]: -0.039 and +0.107 for tooth 15 and -0.033 and +0.091 for tooth 36, and for the milling -0.048 and +0.110 for tooth 15 and -0.038 and +0.096 and for tooth 36.

CONCLUSION

Based on the research conducted and the experience in therapeutic procedures, it can be indicated that the fitting of titanium alloy crowns in SLM and milling meets the clinical requirements. To evaluate the technology, a method was developed that determines the accuracy of mapping the shape of the tooth abutments in the crown substructures for the individual conditions of the patient.

Cognitive changes and neural correlates after oral rehabilitation procedures in older adults: a protocol for an interventional study

BACKGROUND

Epidemiological studies show an association between masticatory function and cognitive impairment. This has further strengthened the notion that tooth loss and impaired masticatory function may be risk factors for dementia and cognitive decline. Animal experiments have indicated a causal relationship and several possible mechanisms have been discussed. This evidence is, however, lacking in humans. Therefore, in the current interventional study, we aim to investigate the effect of rehabilitation of masticatory function on cognition in older adults.

METHODS

Eighty patients indicated for prosthodontic rehabilitation will be randomly assigned to an experimental or a control group. Participants will conduct neuropsychological assessments, masticatory performance tests, saliva tests, optional magnetic resonance imaging, and answer questionnaires on oral health impact profiles and hospital anxiety and depression scale before, 3 months, and 1 year after oral rehabilitation. The difference between the two groups is that the control group will be tested an additional time, (at an interval of about 3 months) before the onset of the oral rehabilitation procedure. The primary outcome is a change in measures of episodic memory performance.

DISCUSSION

Although tooth loss and masticatory function are widespread in older people, it is still an underexplored modifiable risk factor potentially contributing to the development of cognitive impairment. If rehabilitation of masticatory function shows positive effects on the neurocognitive function, this will have great implications on future health care for patients with impaired masticatory status. The present project may provide a new avenue for the prevention of cognitive decline in older individuals.

TRIAL REGISTRATION

The protocol for the study was retrospectively registered in ClinicalTrials.gov Identifier: NCT04458207, dated 02-07-2020.

Clinical evaluation of monolithic zirconia multiunit posterior fixed dental prostheses

STATEMENT OF PROBLEM

Monolithic zirconia restorations have been evaluated with in vitro studies, but limited clinical evidence of their longevity and reliability is available.

PURPOSE

The purpose of this clinical study was to evaluate the clinical performance of posterior multiunit glazed monolithic zirconia fixed dental prostheses.

MATERIAL AND METHODS

A total of 20 participants received 33 monolithic posterior zirconia fixed dental prostheses (Zolid white; Amann Girrbach AG) with minimally invasive preparations. Bilaterally supported fixed dental prostheses with a connector area of at least 9 mm² were luted with resin-modified glass ionomer cement. The clinical evaluations were performed after 1 week, 6 months, and then annually after completion of the treatment. The biologic outcomes were evaluated by assessing the pocket depth, attachment level, plaque control, bleeding on probing, caries, and tooth vitality. Esthetics and the functional performance of the prostheses (color match, cavosurface marginal discoloration, anatomic form, marginal adaptation) were evaluated as per the rating scales of Cvar and Ryge. An analysis of survival was made by using the Kaplan-Meier method.

RESULTS

After 39.8 ±16.7 months of observation, the overall survival rate of the monolithic zirconia multiunit posterior prostheses was 93.9%. No caries were found on the abutment teeth, signs of gingivitis were noted in 1 participant after 24 months, and increased probing depths of the abutment teeth were detected in 5 prostheses (15.1%). No loss of retention was detected. Two prostheses had to be replaced: 1 because of a biologic complication and 1 because of a technical complication. The remaining 31 prostheses received Alfa scores for marginal adaptation, cavosurface marginal discoloration, and caries. Twenty-seven (87.1%) prostheses were rated as Alfa and 4 (12.9%) as Bravo for anatomic form. The color match was noted as Alfa in 15 (48.3%) prostheses, and 16 (51.6%) were rated as Bravo.

CONCLUSIONS

Monolithic zirconia restorations demonstrated a reliable treatment option after medium-term clinical use for the replacement of missing posterior teeth.

Material preferences for tooth-supported 3-unit fixed dental prostheses: A survey of German dentists

STATEMENT OF PROBLEM

Different material options are available for fixed dental prostheses (FDPs), but valid data on the favored materials of German dentists for 3-unit FDPs are lacking. It is unclear whether preferences depend on the individual characteristics of the dentists or their dental practices.

PURPOSE

The purpose of this survey was to identify the preferred material selection of German dentists for the fabrication of tooth-supported 3-unit FDPs depending on the location of the abutment teeth and the individual characteristics of the dentist or the dental practice.

MATERIAL AND METHODS

A survey was developed that included questions on the demographic characteristics (sex, area of expertise, age group, time since graduation, number of inhabitants, and the postal code of the dental practice or dental school) of the participating dentist and their preferred materials for the fabrication of tooth-supported 3-unit FDPs. Three clinical scenarios (anterior maxillary FDP, posterior maxillary FDP, posterior mandibular FDP) were presented. The dentists were allowed to select from predefined options or to give a free answer. For comparisons of characteristic associations, the number of inhabitants was chosen to represent the characteristics of the dental practice, and sex and time since graduation were selected to represent the characteristics of the dentist. Group comparisons were conducted with Chi-square tests (α=.05).

RESULTS

A response of 721 dentists from all parts of Germany was received, and data from 688 dentists were included in the analyses. Ceramic was the most preferred material for the fabrication of 3-unit FDPs independent of the location of the abutment teeth with veneered zirconia as the favored option. Metal-ceramic was ranked second. The time since graduation ≤15 years was associated with a preference of ceramic over metal-ceramic for the anterior restoration (P<.001).

CONCLUSIONS

Most participating dentists selected appropriate restorative materials depending on the individual clinical setting presented in the survey. For the anterior 3-unit FDP, time since graduation was associated with the preference for a restorative material. Some dentists selected lithium-X-silicate ceramics for situations beyond their recommended indication range.