Prognosis of double crown-retained removable dental prostheses compared with clasp-retained removable dental prostheses: A retrospective study

Balancing Function and Proprioception: A Case Report Featuring Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM)-Fabricated Marburg Denture System

The ultimate purpose of a partial prosthetic denture is to protect the rest of the teeth as their discarded functionality is being put back together. A Marburg double crown is a form of retainer that works well by providing splinting action between many abutment teeth as well as retention and support. Compared to traditional clasp-retained removable partial dentures (RPDs), the Marburg double crown transfers load to the abutment teeth's long axis. The Marburg double crown system fabricated efficiently using the computer-aided design/computer-aided manufacturing (CAD/CAM) system for treating partially edentulous patients is highlighted in this case report.

Long-term assessment of the periodontal health of removable partial denture wearers: A systematic review and meta-analysis

STATEMENT OF PROBLEM

The long-term effects of wearing removable partial dentures (RPDs) remain unclear.

PURPOSE

This systematic review addressed the question "Is the long-term use of RPDs deleterious to the remaining teeth?"

MATERIAL AND METHODS

This review was guided by the preferred reporting items for systematic reviews and meta-analyses (PRISMA) checklist. Six databases and nonpeer-reviewed literature were searched in April 2024 without language or follow-up restrictions. Only clinical studies evaluating RPD long-term use were included. The risk of bias and evidence certainty were assessed (RoB 2.0; ROBINS-I; GRADE), and meta-analyses were conducted for survival rate and periodontal health (α=.05).

RESULTS

A total of 5577 records were identified, and 46 studies covering data from 4359 prostheses and 4072 participants (mean age 60 ±5.2 years) were included. A low to moderate risk of bias was found. A 5-year survival rate of 95.1% (ER=0.951; 95% CI=0.900 to 0.977; P<.001) and 91.7% (ER=0.917; 95% CI=0.870 to 0.948; P<.001) was found for cast-clasp RPD and RPDs retained by telescopic crowns respectively, with no difference between them (P=.71). Abutments (OR=1.99, 95% CI=1.32 to 3.01; P=.001) and nonvital teeth (HR=2.961; 95% CI=2.023 to 4.335; P<.001) presented a higher risk of extraction after 5 years. Tooth mobility (P=.98) and probing depth (P=.50) remained unchanged, while the gingival index increased (MD=0.477 (95% CI=0.12 to 0.83; P=.008).

CONCLUSIONS

A high survival rate was found for both cast-clasp RPD and RPDs retained by telescopic crowns, with few periodontal changes to the remaining teeth.

Outcomes of abutment teeth with double crowns over an observation period of 27 years

PURPOSE

The aim of this retrospective study was to determine the outcome of double crowns (DCs) using pooled data over a period of 27 years.

METHODS

Billing data were obtained from the digital accounting system of a university dental clinic. All DCs inserted and invoiced from January 1, 1992, to December 31, 2019, were collected. The maximum observation period of a DC was determined by a recorded follow-up or the occurrence of a target event. Target events were divided into primary, i.e., tooth extraction, and secondary, i.e., failure of DC, types. The dataset was analyzed using descriptive statistics and Kaplan-Meier survival and multivariate Cox regression analyses.

RESULTS

A total of 4,097 tooth-supported DCs in 1,148 patients were included in the analysis. The mean observation period for individual DC was 5.32 years. The cumulative survival rates at 5 and 10 years for the primary target event were 89.7% and 73.8%, respectively. The cumulative survival rates at 5 and 10 years for the secondary target event were 83.6% and 60.6%, respectively. In the multivariate analysis, age and metal denture bases were significantly associated with both target events.

CONCLUSIONS

This study confirmed DCs as a reliable and long-term successful treatment option for anchoring removable partial dentures. The use of a metal denture base and a younger patient age might reduce the risk of complications.

Fit and Retention of Cobalt-Chromium Removable Partial Denture Frameworks Fabricated with Selective Laser Melting

PURPOSE

To evaluate fit and retention of cobalt-chromium removable partial denture (RPD) frameworks fabricated with selective laser melting (SLM).

METHODS

Three types of framework for clasp-retained RPDs were virtually designed and fabricated using SLM (n = 30). For comparison, 30 additional frameworks were produced using conventional lost-wax casting. A biomechanical model was created, incorporating extracted teeth mounted on flexible metal posts. Using this model, horizontal constraint forces resulting from a misfit were measured using strain gauges, while vertical forces were not recorded. The constraint force components and resultant forces were determined for all abutment teeth, and the maximum retention force during RPD removal from the model was also assessed. For statistical evaluation, the two fabrication methods were analyzed by calculating the means and standard deviations.

RESULTS

The average horizontal constraint forces showed similar values for both fabrication methods (SLM: 3.5 ± 1.0 N, casting: 3.4 ± 1.6 N). The overall scatter of data for cast RPDs was greater compared to those fabricated using SLM, indicating a better reproducibility of the SLM process. With regard to retention, the intended retention force of 5-10 N per abutment tooth was not attained in one of the cast groups, while it was consistently achieved in all SLM groups.

CONCLUSIONS

This in vitro study found that SLM is a promising option for the manufacture of cobalt-chromium RPD frameworks in terms of fit and retention.

Cumulative 10-year performance of endodontically treated teeth with prosthetic restorations of base metal alloy double crowns with friction pins-a retrospective study

OBJECTIVES

This 120-month follow-up study aimed to investigate the complication rate of abutment teeth after endodontic pretreatment with base metal alloy double crowns with friction pins.

MATERIALS AND METHODS

A total of 158 participants (n = 71, 44.9% women) aged 62.5 ± 12.7 years with 182 prostheses on 520 abutment teeth (n = 459, 88.3% vital) were retrospectively analyzed between 2006 and 2022. Of the endodontically treated abutment teeth, 6.9% (n = 36) were additionally treated with post and core reconstructions. Cumulative complication rates were calculated using the Kaplan-Meier estimator and log-rank test. In addition, Cox regression analysis was performed.

RESULTS

The cumulative complication rate at 120 months for the entire set of abutment teeth was 39.6% (confidence interval [CI]: 33.0-46.2). Endodontically treated abutment teeth (33.8%; CI: 19.6-48.0) were found to have a significantly higher cumulative fracture rate than vital teeth (19.9%; CI: 13.9-25.9, p < 0.001). Endodontically treated teeth restored with post and core reconstructions (30.4%; CI: 13.2-47.6) showed a nonsignificant lower cumulative fracture rate than that of teeth with root fillings only (41.6%; CI: 16.4-66.8, p = 0.463).

CONCLUSIONS

Higher 120-month cumulative fracture rates were observed in endodontically treated teeth. Comparable performance was observed in teeth with post and core reconstructions compared to teeth with root fillings only.

CLINICAL RELEVANCE

If endodontically treated teeth are used as abutments for double crowns, the risk of complications from these teeth should be considered when planning treatment and communicating with the patient.

Technical Complications of Removable Partial Dentures in the Moderately Reduced Dentition: A Systematic Review

The aim of this study was to conduct a systematic literature review with a subsequent meta-analysis on the technical complications and failures of removable partial denture (RPD) therapy in the moderately reduced dentition. A systematic literature search of established medical databases, last updated 06/2022, was conducted. RCTs and prospective and retrospective studies were included that had information on technical complications and failures of RPDs, at least 15 participants, an observation period of at least two years and a drop-out rate of less than 25%. Publications were selected on the title, abstract and full-text level by at least three of the participating authors. The evidence of the included studies was classified using the GRADE system. The bias risk was determined using the RoB2 tool and the ROBINS-I tool. Of 19,592 initial hits, 43 publications were included. Predominantly, retention of the prosthesis, retention loss of anchor crowns (decementations), fractures/repairs of frameworks, denture teeth, veneering or acrylic bases, and a need for relining were reported depending on prosthesis type and observation time. Focusing on technical complications and failures, only very heterogeneous data were found and publications with the highest quality level according to GRADE were scarce. Whenever possible, data on technical complications and failures should be reported separately when referencing the tooth, the prosthesis and the patient for comparability. Prostheses with differing anchorage types should be analyzed in different groups, as the respective complications and failures differ. A precise description of the kinds of complications and failures, as well as of the resulting follow-up treatment measures, should be given.

Telescopic Denture: A Treatment Option for Occlusal Rehabilitation in Partially Edentulous Patients

The rehabilitation of a patient with multiple edentulous spaces, a collapsed occlusal vertical dimension, and compromised abutment teeth is demanding. For treating such patients, various approaches have been put forth over the years, with dental implants having the best results. However, they cannot be used on all patients due to their high cost and surgical limitations. Therefore, removable dentures are still a popular option. Telescopic removable dentures rest on the natural teeth, preserving the alveolar bone while providing good stability and support for the denture. The treatment goal was to establish normal form, function, and aesthetics to uplift the psychological status and maintain occlusal harmony in the patient. In this case report, a 45-year-old female patient who presented with many missing posterior teeth and a collapse in her vertical dimension received full mouth rehabilitation. The patient requested a maxillary denture with no visible metal clasps when smiling. Consequently, a conventional mandibular removable partial denture (RPD) and a cobalt-chromium maxillary telescopic denture were selected as the appropriate treatments. The final restored occlusion and appearance met the patient's satisfaction.

Ten-year clinical performance of non-precious metal double crowns with friction pins in severely reduced dentitions—a retrospective study

Objectives

This follow-up study aimed at collecting long-term data for removable partial dentures (RPDs) retained by double crowns with spark-eroded friction pins (DCP) and comparing them in the presence of severely reduced dentition (SRD) and non-SRD (NSRD, i.e. residual dentition with more than three abutment teeth) after a 10-year wearing period.

Materials and methods

A total of 158 participants (n = 71, 44.9% women) aged 62.5 ± 12.7 years with 182 prostheses on 520 abutment teeth were followed up between 2006 and 2022. The SRD group included 144 RPDs supported by 314 abutment teeth. The data collection was performed retrospectively. 10-year survival rates of RPDs and abutment teeth were determined using the Kaplan–Meier method and compared using the log-rank test for SRD and NSRD, among others. Cox regression analyses were conducted to isolate risk factors for the survival of both RPDs and abutment teeth.

Results

The 10-year cumulative survival rate of all abutment teeth was 65.6% with significantly lower values in the SRD group (53.5%) (p < 0.001). The survival rate for all RPDs was 65.5%. The SRD group showed lower survival rates (57.9%) (p = 0.004). The number and location of the abutment teeth had a significant influence on the survival rates of the RPDs and the abutment teeth. Age, sex, jaw, relining, and vitality had a significant influence on the abutment teeth survival rates.

Conclusions

RPDs showed an acceptable clinical survival rate after 10 years. The number, location, and vitality of abutment teeth were factors that influenced the survival of both RPDs and abutment teeth.

Clinical relevance

Consideration of the influencing factors found can help improve the prognostic assessment of double crown-retained dentures in the context of prosthetic therapy planning.

Full Mouth Rehabilitation Using Telescopic Removable Prosthesis

A female, aged 55 years, was presented to the clinic concerned with her inability to function properly due to missing teeth and collapse of her vertical dimension. On examination, remaining tooth position of the upper arch was favorable for telescopic denture and remaining tooth position of the lower arch was favorable for removable prosthesis. The patient requested an aesthetic maxillary and mandibular denture with no visible metal clasps on smiling. Therefore, upper telescopic removable complete denture and lower chrome cobalt removable prostheses were suggested to the patient as conservative treatment to reestablish her occlusal vertical dimension and restore her aesthetics and function.

Digital technology for fabrication of removable dental prosthesis with double crowns combining fiber-reinforced composite and zirconia

PATIENTS

This clinical report describes the process for fabricating a double-crown-retained removable dental prosthesis combining a fiber-reinforced composite and zirconia using digital technology. An 83-year-old woman presented with gingival swelling around the maxillary right premolar. The swollen tooth was the abutment tooth of a cross-arch fixed partial denture. An intraoral scanner (IOS) and computer-aided design/manufacturing as digital technology were used to plan treatment with a double-crown-retained removable dental prosthesis. A metal-free prosthesis using zirconia for the primary crown and fiberglass-reinforced composite resin for the secondary crown was planned, and the patient consented to the treatment plan. After autotransplantation of a tooth as one of the abutments, the IOS was used to obtain digital scans of the prepared surface of the abutment teeth, opposing dentition, and occlusal relationships. First, primary crowns were milled using zirconia. Next, the intraoral scanner obtained a pick-up impression of the primary crowns, and secondary crowns were designed and milled from the fiber-reinforced composite. After delivery, the patient expressed satisfaction with the functionality, esthetics, and fit of the double-crown-retained removable dental prosthesis.

DISCUSSION

Digital technology offers many advantages such as efficient fabrication of double crowns, reduced material costs, improved biocompatibility, and good aesthetics of metal-free materials.

CONCLUSION

This clinical report describes the application of digital technology for the fabrication of a double-crown-retained removable dental prosthesis combining a fiber-reinforced composite and zirconia, resulting in patient satisfaction.

Retentive force of conical crowns combining zirconia and fiber-reinforced composite

PURPOSE

This study investigated the retentive force of conical crowns combining zirconia primary and fiber-reinforced composite (FRC) secondary crowns and their changes due to aging.

METHODS

Zirconia primary crowns were produced with a convergence angle of 3°. Thirty-two secondary crowns were milled from FRC and divided into two groups (n = 16/group) based on the polishing method of the secondary crown inner surfaces: diamond paste (Group 1) and silicone points (Group 2). After fitting the secondary crowns with different fitting forces (F), loosening forces (L) were determined. Tests were repeated after an occlusal stop (OS) was added to the secondary crown and artificial aging (10,000 insertion/removal cycles). Data were compared using the Wilcoxon and Mann-Whitney U tests.

RESULTS

Crowns without an OS showed L/F ratios of 0.4586 (Group 1) and 0.4104 (Group 2). With an OS, maximum retention was not significantly affected by the polishing method and could be limited to L_max = 19.31±7.77 N (Group 1) and L_max = 16.12±5.92 N (Group 2).

CONCLUSIONS

These findings suggest that the combination of conical zirconia primary and FRC secondary crowns can obtain acceptable retentive forces that are not affected by aging if the inner surfaces are polished with diamond paste. OS generation could limit maximum retention, but should be adjusted if the target value of 10 N is not to be exceeded. With a change of the convergence angle to 4°, L/F values for crowns without an OS would be close to 1/3, which is considered ideal for conical crowns.

CLINICAL SIGNIFICANCE

The combination of zirconia primary crowns and FRC secondary crowns was found feasible to ensure the required retention for clinical use over a long time span. Furthermore, it offers an alternative to metal-based restorations while ensuring high levels of biocompatibility and esthetics.

Survival Rate of Removable Partial Dentures with Mandibular Bilateral Free End Saddle: A Retrospective Study

The purpose of this study was to investigate the survival of removable partial dentures with a mandibular bilateral free end saddle (BFES) and abutment teeth in a clinical setting. Only mandibular dentures with a BFES were included (10 or fewer present teeth, and fewer than 4 occlusal units). The endpoints were replacement of denture and loss of abutment teeth. A total of 128 dentures and 595 abutment teeth were analyzed. Nineteen dentures had to be replaced during the observation period (mean duration: 11.4±6.9 years; range: 3 to 36 years). According to Kaplan-Meier analysis, the survival rate was 93.2% at 10 years and 68.6% at 20 years. The estimated mean survival period was 27.8 years. Single-factor analysis using the log-rank test showed that no factor investigated had a significant influence. The main reason for denture replacement was loss of abutment teeth (47.4%). The survival rate of the abutment teeth was 91.3% at 10 years and 77.3% at 20 years. The analysis revealed 4 significant risk factors: male sex (hazard ratio [HR]: 1.78); premolars (HR: 1.67); a lower number of abutment teeth (HR: 3.24); and history of endodontic treatment (HR: 2.79). The removable partial dentures with a mandibular BFES in this study lasted over 20 years, and their survival was influenced by loss of abutment teeth. Dentures are used continuously over long periods of time and should therefore be designed to allow easy adjustment when abutment teeth are lost.

Intraoral scanner and computer-aided design/manufacturing technology for the fabrication of double-crown-retained removable dental prosthesis: A clinical report

PATIENT

This clinical report describes treatment with a double-crown-retained removable dental prosthesis fabricated using an intraoral scanner (IOS) and computer-aided design/manufacturing technology (CAD/CAM). A 68-year-old female patient presented with complaints of missing maxillary right first and left second premolars. CAD/CAM technology was applied to plan treatment with a double-crown-retained removable dental prosthesis. The patient consented to this treatment option but did not want orthodontic treatment for the anterior crossbite of the right side. After the definitive preparation of the abutment teeth, the shape of the provisional restoration was adjusted to match the definitive prosthesis. An IOS was used to obtain digital scans of the provisional restoration, occlusion, antagonist arch, and prepared surface of the abutment teeth. First, the primary crowns were milled from cobalt-chromium alloy. Next, using an intraoral scanner, a pickup impression of the primary crowns was performed, and the secondary crowns were designed, milled, and veneered. After delivery, the patient expressed satisfaction with the functionality, esthetics, and fit of the double-crown-retained removable dental prosthesis.

DISCUSSION

The surface of the primary crowns was coated with scan spray when the pick-up impression was made using the IOS. Practice is needed to achieve a thin and homogeneous coating with scan spray to improve reproducibility.

CONCLUSION

Double-crown-retained removable dental prostheses can be successfully fabricated using an IOS and CAD/CAM technology, resulting in patient satisfaction.

Removable partial dentures retained by hybrid CAD/CAM cobalt-chrome double crowns: 1-year results from a prospective clinical study: CAD/CAM cobalt-chrome double crowns: 1-year results

OBJECTIVES

Computer-aided design and manufacturing (CAD/CAM) has been successfully used to replace conventional steps in the fabrication of double crowns, creating hybrid-workflows that might facilitate the wider application of these restorations in the future. However, in-vivo data are still lacking.

METHODS

A prospective clinical trial was designed in which 20 patients (median age = 69 years; n women = 10) with 73 abutment teeth who needed a double-crown-retained removable partial denture (RPD) were consecutively recruited. While most of the work steps were done conventionally, gypsum models were digitized with a laboratory scanner to allow CAD/CAM fabrication of primary crowns and secondary structures. DentalDesigner software (3Shape) was used in combination with milling unit PrograMillPM7 and Co-Cr- blanks (Ivoclar-vivadent). Connectors were milled from wax, transferred to Co-Cr using lost-wax technique and bonded to the secondary crowns. Clinical follow-ups were scheduled 6 and 12 months after prosthesis insertion. Outcome parameters were complication-free survival of RPDs and abutment teeth after one year.

RESULTS

After 12 months, complication-free survival was 74% and 91% for the RPDs and abutment teeth, respectively. Complications comprised decementations (n = 5), abutment tooth fractures (n = 2), fracture of denture teeth (n = 1), and loss of abutment teeth (n = 1). These complications were easily manageable, resulting in 1-year survival of 100% for CAD/CAM RPDs.

CONCLUSIONS

First data on short-term complication rates of CAD/CAM double-crown-retained RPDs appear promising. To gather further evidence, prospective clinical trials over a longer follow-up time and with larger patient groups are required.

CLINICAL SIGNIFICANCE

Hybrid CAD/CAM double-crown retained RPDs showed a successful clinical application after one year of follow-up. Further research is needed to evaluate their performance in comparison to conventional manufacturing methods.

Retentive force of telescopic crowns combining fiber-reinforced composite and zirconia

PURPOSE

This study investigated changes in the retentive force of telescopic crowns fabricated by combining a zirconia primary crown and a fiber-reinforced composite (FRC) secondary crown.

METHODS

Primary zirconia crowns were produced with a nominal convergence angle of 0°. Forty-eight secondary crowns were milled from FRC and divided into three study groups (n=16/group) based on milling parameters and post-milling adjustment. The offset parameter used for the final milling step of the inner crown surface was adjusted for a tight initial fit in Group 1 (milling offset: +10 µm, i.e., 2 × 10 µm = 20 µm lower inner diameter compared with the CAD file of the crown) and for improved initial fit (milling offset: -10 µm, i.e., an enlargement of the inner crown diameter by 2 × 20 µm = 40 µm in relation to Group 1) in Groups 2 and 3. The inner surfaces of the secondary crowns were polished with diamond paste in Groups 1 and 2, and silicon points were used for Group 3. The retentive force was measured using a universal testing device. The secondary crown was placed on the primary crown, with the final fitting force set to a load of 100 N. This test was conducted before and after aging (10,000 insertion/removal cycles) under dry and wet conditions. A generalized linear model was used to estimate the differences in the retentive force to elucidate the effects of the milling parameters and polishing methods.

RESULTS

We realized an initial retentive force of approximately 10 N. In Groups 2 and 3, the difference was statistically significant between the dry and wet conditions before aging (P < 0.05). There was no significant difference between the dry and wet conditions after aging in any of the groups (P > 0.05).

CONCLUSIONS

An adequate initial retentive force can be achieved with telescopic crowns combining zirconia and FRC.

Influence of rigidity of retainers on dynamic behavior of implant-supported removable partial dentures

Background

Implant-supported removable partial dentures (ISRPDs) are an effective treatment for partially edentulous patients. ISRPDs improve patients’ satisfaction and oral function to a greater extent than RPDs by improving denture stability and enhancing support. However, the effect of a type of direct retainer on displacement of the abutment teeth and dentures in ISRPDs remains unclear. Therefore, we made a resin mandibular model of unilateral mandibular distal-extension partial edentulism for mechanical simulation and compared the dynamic behavior of the abutment teeth and the denture base among different tooth-borne retainers with various rigidities for RPDs and ISRPDs.

Methods

A resin mandibular model for mechanical simulation that had unilateral mandibular distal-extension edentulism and was missing the first molar, second molar, first premolar, and second premolar, and a denture fabricated from the patient’s computed tomography images were used. Three types of direct retainers with different connecting rigidities were evaluated. The vertical displacement of the denture base and buccal and lingual sides and the mesial displacement of the abutment teeth were measured.

Results

Regardless of the rigidity of the direct retainers and loading positions, the displacement of the denture bases in the ISRPDs was significantly smaller than that in the RPDs (P < 0.001). There was no significant difference in vertical displacement of the denture bases among direct retainers with various connecting rigidities in the ISRPDs. Conversely, horizontal displacement of the abutment teeth in both the RPDs and ISRPDs tended to be larger with the cone crown telescope, which has high rigidity, than with the cast cingulum rest and wire clasp, which have much lower rigidities.

Conclusion

Our results suggested that cast cingulum rest and wire clasps as direct retainers are appropriate ISRPDs to minimize denture movement and suppress displacement of the remaining teeth in patients with unilateral mandibular distal-extension partial edentulism.

Clinical outcomes of rigid and non-rigid telescopic double-crown-retained removable dental prostheses: An analytical review

PURPOSE

The objective of this literature review was to analyze the cumulative survival rates (CSRs) of rigid and non-rigid double-crown-retained removable dental prostheses.

MATERIALS AND METHODS

Screening of the literature published from January 1995 to December 2019 was performed by using electronic data base (Pubmed) and manual search. The CSRs of rigid and non-rigid double crown removable dental prostheses were investigated.

RESULTS

A total of 403 articles were reviewed and 56 relevant articles of them were selected. Subsequently, 25 articles were included for data extraction. These articles were classified according to rigid and non-rigid type double crowns and further subdivided into teeth, implants, and teeth-implant combination types. The CSRs of rigid type double crown ranged from 68.9% to 95.1% of 5 to 10 years in tooth abutments, 94.02% to 100% over a 3-year mean observation periods in implant abutments, and 81.8% to 97.6% in tooth-implant combination. Non-rigid type double crowns had various CSR ranges from 34% to 94% maximum during 10 years observation in teeth abutment. The CSRs of non-rigid type had over 98% in implant abutments, and ranged from 85% to 100% in tooth-implant combination.

CONCLUSION

The CSRs of double crowns varies according to types. With accurate evaluation of the remaining teeth and plan of the strategic implant placement, it could be successful treatment alternatives for partially or completely edentulous patients.

Clinical performance of non-precious metal double crowns with friction pins in severely reduced dentitions

OBJECTIVES

Several in vitro studies have investigated the retention of double crowns with friction pins (DCP); however, clinical data on their long-term success have not been reported. We sought to evaluate the 5-year survival rate of DCPs in patients with severely reduced dentition (SRD) and not severely reduced dentition (NSRD).

MATERIALS AND METHODS

A total of 158 patients were treated with 182 dentures on 520 abutment teeth between 2006 and 2016. The SRD group included 144 dentures that had been inserted on 314 abutment teeth. We evaluated the influence of age, sex, jaw, number, tooth vitality, and abutment teeth localization (according to Steffel's classification) on the 60-month survival rates of dentures and abutment teeth using the Kaplan-Meier estimator, logrank test, and Cox regression.

RESULTS

The cumulative 60-month survival rate was 84.3% (CI 77.1-91.5%) for all dentures; however, the survival rate in the SRD group (80.3%; CI 71.5-89.1%) was significantly lower than in the NSRD group (100%; p = 0.04). Dentures classified in Steffel's class A had the lowest survival rate (51.5%; CI 30.9-72.1%). Number, location, and vitality of the abutment teeth had a significant impact on survival rate.

CONCLUSIONS

DCP dentures showed comparable clinical long-term success to double crown systems that have been previously reported in the literature. The number, localization, and vitality of abutment teeth had the greatest influence on the survival rates of denture and abutment teeth.

CLINICAL RELEVANCE

DCP dentures have an acceptable 5-year survival rate. Clinical treatment planning must take into account key factors associated with the prognosis of the abutment teeth.

Conical zirconia telescoping into electroformed gold: A retrospective study of prostheses supported by teeth and/or implants

BACKGROUND

Telescopic prostheses are an evidence-based treatment modality, and conical zirconia crowns and electro-formed gold copings have been used for dentures supported by teeth and/or implants.

PURPOSE

We aimed to evaluate the survival rates of zirconia-based tooth/implant restorations.

MATERIALS AND METHODS

A total of 126 telescopic overdentures, all retained by conical zirconia crowns and electro-formed gold copings, were retrospectively evaluated and failures analyzed for abutment configurations. Survival rates and modifying factors were evaluated by Kaplan-Meier analysis, log-rank testing, and Cox regression analysis.

RESULTS

We evaluated observation periods of up to 11.5 years (mean: 45.25 ± 25.11 months). Five-year prosthesis survival was 96.9 ± 2.2% (95% CI: 92.6-100). Six dentures had been lost, and these failures were significantly associated with specific abutment configurations.

CONCLUSIONS

Within the limitations of this retrospective study, the concept of conical zirconia telescoping into electro-formed gold provides a viable alternative to other telescopic designs used for removable dental prostheses. The concept is well suited especially for tooth/implant-supported prosthetic rehabilitation.