Telescopic Crowns Research Articles

Suitability of Secondary PEEK Telescopic Crowns on Zirconia Primary Crowns: The Influence of Fabrication Method and Taper.

This study investigates the retention load (RL) between ZrO2 primary crowns and secondary polyetheretherketone (PEEK) crowns made by different fabrication methods with three different tapers. Standardized primary ZrO2 crowns were fabricated with three different tapers: 0°, 1°, and 2° (n = 10/group). Ten secondary crowns were fabricated (i) milled from breCam BioHPP blanks (PM); (ii) pressed from industrially fabricated PEEK pellets (PP) (BioHPP Pellet); or (iii) pressed from granular PEEK (PG) (BioHPP Granulat). One calibrated operator adjusted all crowns. In total, the RL of 90 secondary crowns were measured in pull-off tests at 50 mm/min, and each specimen was tested 20 times. Two- and one-way ANOVAs followed by a Scheffé’s post-hoc test were used for data analysis (p < 0.05). Within crowns with a 0° taper, the PP group showed significantly higher retention load values compared with the other groups. Among the 1° taper, the PM group presented significantly lower retention loads than the PP group. However, the pressing type had no impact on the results. Within the 2° taper, the fabrication method had no influence on the RL. Within the PM group, the 2° taper showed significantly higher retention load compared with the 1° taper. The taper with 0° was in the same range value as the 1° and 2° tapers. No impact of the taper on the retention value was observed between the PP groups. Within the PG groups, the 0° taper presented significantly lower RL than the 1° taper, whereas the 2° taper showed no differences. The fabrication method of the secondary PEEK crowns and taper angles showed no consistent effect within all tested groups.

In Vitro Analysis of the Tribological Behaviour of Different Material Combinations for Telescopic Crowns

Telescopic crowns are used to connect removable dental prostheses with the remaining dentition. Several material combinations are used for manufacturing primary and secondary crowns. The present experimental study analysed the influence of different material combinations on the long-term development of surface roughness and pull-off forces. Six different material combinations were tested. Secondary crowns were manufactured either by casting or electroforming. Each material combination was tested with n = 10 specimens. A material testing device with integrated power sensors was used for 10,000 cycles per test. Signs of wear were identified by surface roughness measurements, and visualized by a scanning electron microscope (SEM) and X-ray spectroscopy (EDX) technologies. Statistical significances were tested by using the U-Test with Bonferroni correction. The choice of materials and the manufacturing process were found to influence the long-term development of pull-off forces as well as wear-associated surface roughness. Combinations of different groups of materials for primary and secondary crowns showed favourable results. Worse results were found for the combination pure titanium and pure titanium and the combination high gold alloy and electroformed gold. Wear-associated surface roughness was higher for combinations of similar or identical groups of materials. For manufacturing telescopic crowns, combinations of different groups of materials are preferred. For secondary crown manufacturing, electroforming is superior to casting.

Retention Load Values of Telescopic Crowns Made of Y-TZP and CoCr with Y-TZP Secondary Crowns: Impact of Different Taper Angles.

This study aimed to examine and compare the retention load values (RL) of different telescopic crown assemblies (Y-TZP and CoCr primary crowns with electroformed and Y-TZP secondary crowns each) with three different taper angles (0°, 1° and 2°). Thirty Y-TZP primary crowns with electroformed gold copings (Z/G group) and Y-TZP secondary crowns (Z/Z group) and 30 CoCr primary crowns with electroformed gold copings (C/G group) and Y-TZP secondary crowns (C/Z group), each with taper angles of 0°, 1° and 2°, were fabricated, respectively. With the exception of the electroformed gold copings, all specimens were Computer-Aided-Design/Computer-Aided-Manufacturing (CAD/CAM)-milled, then sintered and afterwards manually adapted. In order to stabilize the gold copings, they were fixed in a tertiary structure. The secondary crowns were constructed with a hook, which ensured self-alignment with an upper chain. Afterwards, 20 pull-off test cycles were performed in a universal testing machine under artificial saliva and after weighing the secondary crowns with a 5 kg object for 20 s. Data were analyzed by one-way and two-way Analysis of Variance (ANOVA). C/Z with 1° showed higher (p = 0.009) RL than 0° and 2° tapers. C/G at 1° also showed higher (p = 0.001) RL than at tapers of 0° and 2°. Z/G and C/G at 0° showed lower RL than Z/Z and C/Z (p < 0.001). Primary crowns had no impact on the 0° group. Z/G showed lower RL as compared to C/Z within the 1° group (p = 0.007) and Z/Z in the 2° group (p = 0.006). The primary crown material had no influence on RL. Electroformed copings showed lower RL. Further investigations for 1° as well as for the long-term performance after thermomechanical aging are necessary.

Retention Load of Telescopic Crowns with Different Taper Angles between Cobalt-Chromium and Polyetheretherketone Made with Three Different Manufacturing Processes Examined by Pull-Off Test.

To investigate the retention loads of differently fabricated secondary telescopic polyetheretherketone (PEEK) crowns on cobalt-chromium primary crowns with different tapers. Cobalt-chromium primary crowns with 0°, 1°, and 2° tapers were constructed, milled, and sintered. Corresponding secondary crowns were fabricated by milling, pressing from pellets, and pressing from granules. For these nine test groups, the pull-off tests of each crown combination were performed 20 times, and the retention loads were measured (Zwick 1445, 50 mm/min). Data were analyzed using linear regression, covariance analysis, mixed models, Kruskal-Wallis, and Mann-Whitney U-test, together with the Benferroni-Holm correction. The mixed models covariance analysis reinforced stable retention load values (p = 0.162) for each single test sequence. There was no interaction between the groups and the separation cycles (p = 0.179). Milled secondary crowns with 0° showed the lowest mean retention load values compared to all tested groups (p = 0.003) followed by those pressed form pellets with 1°. Regarding the different tapers, no effect of manufacturing method on the results was observed within 1° and 2° groups (p = 0.540; p = 0.052); however, among the 0° groups, the milled ones showed significantly the lowest retention load values (p = 0.002). Among the manufacturing methods, both pressed groups showed no impact of taper on the retention load values (p > 0.324 and p > 0.123, respectively), whereas among the milled secondary crowns, the 0° taper showed significantly lower retention load values than the 1° and 2° taper (p < 0.002). Based on these results, telescopic crowns made of PEEK seem to show stable retention load values for each test sequence; however, data with thermo-mechanical aging are still required. In addition, further developments in CAD/CAM manufacturing of PEEK materials for telescopic crowns are warranted, especially for 0°.

Patient-reported outcome and its association with attachment type and bone volume in mandibular implant overdenture.

To determine oral health-related quality of life (OHRQoL) and denture satisfaction (DS) in patients provided with mandibular implant-supported overdentures (ISOD) retained by two different attachment types, and the association of mandibular bone volume with the change in patient-reported outcome, before and after implant treatment. Thirty-four patients (mean age 60.70 ± 8.7years) received telescopic crown or locator attachments for ISOD and completed OHIP-14 (Malaysian version) and DS questionnaires, at baseline (T0 ) with new conventional complete dentures (CCD) and 3months (T1 ) and 3years (T2 ) after ISOD conversion. Mandibular bone volume was calculated from cone beam computed tomography (CBCT) datasets using Mimics software. Mean changes (MC) in OHIP-14 and DS at intervals were analyzed using the Wilcoxon signed-rank test and effect size (ES). The association of bone volume, implant attachment type, and other patient variables with the change in OHIP-14 and DS were determined using multivariate linear regression analysis. The MC in OHIP-14 and DS scores from T0 to T1 and T2 showed significant improvement with moderate and large ES, respectively. Regression analyses for the change in OHIP-14 score from T0 to T2 showed significant association with implant attachment type (P=0.043), bone volume (P=0.004), and baseline OHIP-14 (P=0.001), while for DS, the association was only significant with baseline DS score (P=0.001). Improvement in patients' OHRQoL and satisfaction with ISOD was associated with their baseline ratings. Mandibular bone volume had a stronger association for improvement in OHRQoL compared to type of attachment.

Effectivity and durability of telescopic dentures on abutment teeth

In a study, the effectivity and durability of telescopic dentures on abutment teeth provided with telescope crowns were investigated. The prognosis for the prosthetic structure and for the abutment teeth were both investigated. The survival rate of 234 telescopic dentures (886 abutment teeth) in 147 patients in a general dental practice were retrospectively evaluated on the basis of a status study. The mean survival rate was calculated. This is the moment when 50% of the telescopic dentures had failed. For telescopic dentures in the maxilla, this was 22.3±2.8 years, which did not represent a statistically significant difference from the mandible (20.9±1.9 years). Of the 886 abutment teeth that were used, 127 (14.3%) were extracted after an average period of 11.7 years. Periodontal complications were the primary reason for extraction. Based on this investigation, one could conclude that telescopic dentures are also a durable and sustainable solution in the long term. Loss of abutment teeth is relatively rare and has limited influence on the survival of the prosthetic structure.

The Use of Telescopic Crowns in Removable Partial Denture Treatment for Patients with Severe Periodontal Disease: Two Patient Case History Reports

Two patient case histories are described as examples of treatment of severe periodontitis in severely compromised partial dentitions. Management consisted of periodontal treatment and telescopic crown support for removable partial dentures with friction pin retention.

MARGINAL BONE LEVEL EVALUATION OF IMPLANT SUPPORTED KENNEDY CLASS I PARTIAL OVERDENTURE USING TELESCOPIC CROWNS VERSUS ACETAL RESIN CLASPS DIRECT RETAINERS

Objectives : This study was conducted to evaluate and compare marginal bone level for abutments of implant supported Kennedy class I partial overdenture using Telescopic Crowns versus acetal resin clasps direct retainers after 18 month of clinical use. Materials & methods : Ten male partially edentulous patients (Kennedy class I) with the premolars are the last standing abutments were selected and all patients were rehabilitated with metallic partial denture supported by two osseointegrated implants one on each side of the lower arch positioned in the area of second molar and were randomly divided into two equal groups according to type of abutments retainers ,Group I; Patients were rehabilitated with Tooth Implant Supported partial overdenture with two telescopic crowns ,Group II; Patients were rehabilitated with Tooth Implant Supported partial overdenture with two Acetal Resin clasps direct retainer on each side. Evaluation by measuring marginal bone level for main abutments was made at the time of insertion, after 6 month ,after 12 month and last after 18 month using radiographic evaluation. Results: partial overdentures retained by telescopic crowns showed significant increase in marginal bone loss as compared with Acetal resin clasps retainers. Conclusion: using tooth implant partial overdentures retained by Acetal resin clasps shows better effect on supporting structure as compared by partial dentures with telescopic crowns retainers.

Implant-Supported Telescopic Crown-Retained Overdentures for Oral Rehabilitation of Patients with Severe Bony Defects: A 5-Year Retrospective Study.

To evaluate the performance of dental implant-supported telescopic crown (TC)-retained overdentures to restore the oral function of patients who have insufficient jawbone volume resulting from tumor resection or trauma. From January 2004 to December 2008, implant-supported TC-retained overdentures were used to restore the oral function of patients with severe bony defects resulting from tumor resection or trauma. Clinical data, including implant success and survival rates, biologic and mechanical complications, prosthodontic maintenance efforts, and patient satisfaction, were analyzed annually after delivery of the final prostheses. Twenty-four patients were treated, and a total of 88 implants were inserted to support TC-retained overdentures. The mean modified plaque index of implants remained low (<20%), and the majority of implants (>76.3%) in the study showed the absence of bleeding on probing at follow-up visits. Peri-implant marginal bone loss (MBL) ranged from 0.8 to 1.2 mm. There was no statistically significant difference in the MBL between maxillary and mandibular implants (P = .43). The implant success rate was 100% after 5 years, and the prosthodontic maintenance and complication rate was 0.22 times per year. More than 90% of patients were satisfied with the restoration of their oral function using TCs. Based on our study of 24 patients treated with TC-retained overdentures, it appears that this treatment may be a viable option for patients with insufficient jawbone volume.

Why, when, and how general practitioners restore endodontically treated teeth: a representative survey in Germany.

The purpose of this study was to assess current opinions, applied techniques, and materials for the restoration of endodontically treated teeth (ETT) in a nationwide survey in Germany. Completed questionnaires from 1,648 dentists were returned (response rate 63%). In general, posts were reported to be used more frequently (51%) for indirect restorations than for direct restorations (21%). Dentists restored anterior teeth (65%) more frequently with direct restorations than posterior teeth (48%). Compared to an earlier survey, fewer dentists stated that posttreatment stabilizes the remaining tooth structure. The ferrule effect as a key success factor was held by the vast majority of dentists (88%). A trend towards adhesive techniques both for post placement and core build-up was observed. Composite resins (49%) were reported to be used twice as much as zinc phosphate cement (24%) for the luting of posts; composite resins were the core build-up material of choice (75%). Amalgam was rarely used (0.2%). Irrespective of the final restoration, fiber posts were the most popular post material (46% for telescopic crowns vs. 69% for single crowns). Adhesive composite core build-ups with and without fiber posts were the predominant treatment approach to restore ETT in Germany. There was widespread agreement with the ferrule effect as a key restorative success factor for indirect restorations. Today, it is general accepted that ferrule preparation is key. Glass-fiber posts appear to be most popular. Still different systems are used depending on type of final restoration, while the reasons to do so remain unclear.

Telescopic crowns as attachments for implant supported removable dentures . A literature review

Telescopic crowns as attachments for implant supported removable dentures . A literature review

Analysis of changes in the value of the retention force in three-part telescopic crowns system manufactured from zirconia- part II

Analysis of changes in the value of the retention force in three-part telescopic crowns system manufactured from zirconia- part II

A systematic review and meta-analysis of removable and fixed implant-supported prostheses in edentulous jaws: post-loading implant loss.

ObjectivesThe aim of this systematic review was to analyze post‐loading implant loss for implant‐supported prostheses in edentulous jaws, regarding a potential impact of implant location (maxilla vs. mandible), implant number per patient, type of prosthesis (removable vs. fixed), and type of attachment system (screw‐retained, ball vs. bar vs. telescopic crown).Material and methodsA systematic literature search for randomized‐controlled trials (RCTs) or prospective studies was conducted within PubMed, Cochrane Library, and Embase. Quality assessment of the included studies was carried out, and the review was structured according to PRISMA. Implant loss and corresponding 3‐ and 5‐year survival rates were estimated by means of a Poisson regression model with total exposure time as offset.ResultsAfter title, abstract, and full‐text screening, 54 studies were included for qualitative analyses. Estimated 5‐year survival rates of implants were 97.9% [95% CI 97.4; 98.4] in the maxilla and 98.9% [95% CI 98.7; 99.1] in the mandible. Corresponding implant loss rates per 100 implant years were significantly higher in the maxilla (0.42 [95% CI 0.33; 0.53] vs. 0.22 [95% CI 0.17; 0.27]; P = 0.0001). Implant loss rates for fixed restorations were significantly lower compared to removable restorations (0.23 [95% CI 0.18; 0.29] vs. 0.35 [95% CI 0.28; 0.44]; P = 0.0148). Four implants and a fixed restoration in the mandible resulted in significantly higher implant loss rates compared to five or more implants with a fixed restoration. The analysis of one implant and a mandibular overdenture also revealed higher implant loss rates than an overdenture on two implants. The same (lower implant number = higher implant loss rate) applied when comparing 2 vs. 4 implants and a mandibular overdenture. Implant loss rates for maxillary overdentures on <4 implants were significantly higher than for four implants (7.22 [95% CI 5.41; 9.64] vs. 2.31 [1.56; 3.42]; P < 0.0001).ConclusionsImplant location, type of restoration, and implant number do have an influence on the estimated implant loss rate. Consistent reporting of clinical studies is necessary and high‐quality studies are needed to confirm the present results.

包括一貫治療システムとしてのコーヌステレスコープ義歯

包括一貫治療システムとしてのコーヌステレスコープ義歯

Telescopic Overdenture and Implant Supported Fixed Partial Denture: A Pragmatic Treatment Approach.

This case report presents a patient who had been rehabilitated with a telescopic overdenture and implant supported fixed partial denture (ISFPD). The treatment process was as follows: (1) fabricating telescopic crowns and overdenture prosthesis for the lower jaw and a temporary complete denture for the upper jaw, (2) using the temporary denture as diagnostic and surgical guide to optimize dental implant placement, and (3) fabricating ISFPD for the upper jaw. Using the patient's existing or temporary denture not only serves as an alternative surgical guide to calibrate the dental implant locations but also helps to finish the restoration at desired dimension, size, and anatomic form.

Analysis of changes in the retention force value in a three-element system of telescopic crown made of zirconia. Part I

Analysis of changes in the retention force value in a three-element system of telescopic crown made of zirconia. Part I

A new technique for retaining double crowns on implants via custom-positioned vertical screws.

This report describes the use of custom-positioned vertical screws (CVS) to attach primary telescopic crowns to implant abutments. In a private practice setting, 37 patients with 40 double crown-retained implant overdentures (IODs) with a clearance fit (Marburg double crowns) were followed. All primary crowns on the 120 implant abutments were retained using CVS. After a mean followup period of 3.55 ± 1.37 years (range: 1.5 to 6.3 years), one abutment screwloosening incident was reported (incidence: 0.08%). No loosening of any of the screw-retained primary crowns occurred. CVS may represent a viable fixation concept for IODs.

Clinical Outcome of Double Crown-Retained Mandibular Removable Dentures Supported by a Combination of Residual Teeth and Strategic Implants.

There is a lack of data regarding the clinical outcome of removable partial dentures (RPDs) supported by a combination of residual natural teeth and implants placed in strategic positions. The aim of the present case series was to conduct a retrospective investigation of the clinical outcome of mandibular tooth-implant-retained partial dentures (TIRPD) rigidly retained via telescopic double crowns. Between 1999 and 2010, 18 patients with reduced residual dentition (1 to 3 natural abutment teeth) and in need of an RPD received 1 to 3 implants in strategic positions for support of the removable prostheses. All TIRPDs were rigidly retained by telescopic crowns according to the Marburg Double Crown (MDC) technique; all prostheses were placed in a private practice. Tooth/implant survival and success rates, prosthetic maintenance requirements, and peri-implant parameters were analyzed retrospectively using patient records and clinical examinations during the final recall appointments. Only patients attending at least annual supportive post-implant hygiene therapy visits (SIT) were included. After a mean functional period of 5.84 ± 3 years (range: 3.01-12.21), 14 patients with 14 dentures supported by 24 implants and 27 teeth (mean number of abutments: 3.6) were available for assessment. Four teeth (survival rate: 85.19%) and no implants (survival rate: 100%) were lost. Peri-implantitis was observed around one implant (4.17%). All 14 dentures were functional (survival rate: 100%) and required only limited maintenance (i.e., screw loosening, acrylic resin fracture repairs, relining) amounting to 0.086 treatments per patient per year (T/P/Y). Within the limitations of this case series, it can be concluded that TIRPDs retained via MDCs might represent a viable treatment option in mandibles with few remaining abutment teeth. Further long-term clinical evaluations with a greater sample size are needed for a more detailed evaluation of this treatment concept.

A 10-year retrospective analysis of clinical results of implant-retained/ supported prostheses in full edentulous patients

To evaluate the 10-year clinical results of implant prostheses in edentulous patients. Between August 1994 and November 2009, 762 implants were placed in 127 patients (162 jaws) with the mean age of (56.0 ± 10.9) years in Peking University, School and Hospital of Stomatology. Sinus lift, guide bone regeneration (GBR) and onlay graft were used according to the indications of bone defect types. Overdentures and fixed bridges were delivered.Overdentures were retained/supported by ball, magnet, telescopic crown or milled bar. Clinical evaluation included peri-implant soft tissue health status, prostheses functional status and complications.Radiographic evaluations were conducted at operation day, 3 months post-operatively, right after prostheses delivery, and annually afterwards. Clinical data were collected and analyzed. Of the 127 patients, 116 were edentulous mandible and 46 edentulous maxilla, with a mean follow-up period 109.2 months(45-228 months). Thirteen implants were lost and the 10-year implant cumulative survival rate was 97.8% and the prostheses success rate was 100.0%. The prevalence of peri-implantitis was 3.8% (29/762). Sixty-seven point nine percent of the patients underwent implant placement without bone graft.Sinus lift technique and guided bone regeneration technique were the most often used with 84.8% (39/46) in the upper jaws and 6.2% (10/162) in the total jaws respectively. Seventy-one percent of the cases(115/162) was overdentures. Telescopic, milled-bar, and magnetic retained/supported overdentures were the most commonly used with 34.8% (40/115) , 27.0% (31/115) , and 20.0% (23/115) respectively. The implant-supported fixed prostheses included adhesive retained fixed bridges and screw retained fixed bridges with the ratio of 19.1% and 80.9% respectively. The prevalence of 10-year post-prosthodontic complications was 53.5% (68 cases). The most common complications were prosthetic and uperstructure complications. The 10-year implant-retained/supported prostheses was a successful modality in edentulous cases.Sinus lift technique and guided bone regeneration technique are the most commonly used techniques with predictable clinical results. Telescopic crowns milled bar and magnet with 4-6 implants retained/supported overdenture were the most often used retention systems and telescopic crown overdenture had more advantages in terms of long-term maintenance and satisfaction.

Unsplinted implants and teeth supporting maxillary removable partial dentures retained by telescopic crowns: a retrospective study with >6years of follow-up.

Data regarding tooth- and implant-supported maxillary removable partial dentures (TIRPDs) are scarce. The objective of this research was to perform a retrospective evaluation of the clinical long-term outcome of maxillary TIRPDs rigidly retained via telescopic crowns in patients undergoing supportive post-implant therapy (SIT). The inclusion criteria were met by 26 patients restored with maxillary TIRPDs between 1997 and 2011 in a private practice. Primary crowns (Marburg double crowns, MDCs) on teeth were cemented, whereas those on implants were screw-retained. Using patient records and data from a cross-sectional clinical examination in 2013, the survival rates of the teeth, implants and prostheses, together with the biological and technical complications, were analyzed. After 6.12±3.80 (range: 2-16) years of loading, 23 non-smoking patients with 23 dentures supported by 60 implants and 66 teeth were available for assessment. Nine teeth (survival rate: 86.36%) were lost, whereas 1 implant (survival rate: 98.36%) failed because of peri-implantitis. Although 30 implants (50%) in 16 patients (69.57%) showed bleeding on probing (BOP+), no further peri-implantitis was observed. The mean peri-implant probing depth (PPD) was 3.68±0.71mm. All dentures were functional and required technical maintenance efforts amounting to 0.128 treatments per patient per year (T/P/Y). Within the limitations of this study, we conclude that TIRPDs retained via MDCs may represent a viable treatment option for patients with residual maxillary teeth.