Retention and fatigue performance of modified polyetheretherketone clasps for removable prosthesis.

PURPOSE: Polyetheretherketone (PEEK) is considered as an alternative to metal material for removable partial denture (RPD). However, the retentive force is not strong as a metal RPD. This study investigated the retention and fatigue performance of PEEK clasps with different proportions of clasp arm engaging the undercut to verify a new strategy to improve their clinical performance. METHODS: Three groups (n = 10/group) of PEEK clasps with their terminal 1/3, 2/3 and the whole of retentive arms engaging the undercut were fabricated along with a group (n = 10) of conventional cobalt-chrome (CoCr) clasps as control group. Retentive forces were measured by universal testing machine initially and at an interval of 1500 cycles for a total of 15,000 fatigue cycles. The fatigue cycles were conducted by repeated insertion and removal of the clasp using fatigue testing machine. Each clasp was scanned by Trios3 scanner before and after fatigue test to obtain digital models. The deformation of the clasp was evaluated by root mean square (RMS) through aligning the two models in Geomagic wrap (2021). Scanning electron microscopy (SEM) and finite element analysis were carried out to observe the abrasion and the von Mises stress of the clasp arm. Kruskal-Wallis H test was used to compare the retentive forces and the RMSs of the studied groups followed by Bonferroni multiple comparisons. RESULTS: The whole of PEEK clasp arm engaging the undercut provided higher mean retentive forces (7.99 ± 2.02 N) than other PEEK clasp groups (P < 0.001) and was closer to CoCr clasps (11.88 ± 2.05 N). The RMSs of PEEK clasps were lower than CoCr clasps (P < 0.05) while the differences among PEEK clasps were of no statistical significance (P > 0.05). SEM showed that evidences of surface abrasion were observed on the section that engaged the undercut for all groups of clasps. The stress concentration mainly occurred on the initial part of the retentive arm. The maximum von Mises stress of each group was below the compressive strength of PEEK. CONCLUSIONS: Proportions of PEEK clasp arm engaging the undercut positively influenced the retentive force and the fatigue resistance of PEEK clasps was superior than CoCr clasps. It is a feasible method to improve the retention of PEEK clasps by increasing the proportion of clasp arm engaging the undercut. Clinical trials are needed to further verify this innovation.

Oral health-related quality of life and reasons for discontinuing partial removable dental prosthesis usage: a cross-sectional study with one to seven years of follow-up.

BACKGROUND: In partial edentulous individuals, a partial removable dental prosthesis (PRDP) is a common dental replacement option to improve oral function and quality of life. However, some patients discontinue using their denture over time. The aim of this study was to determine the prevalence and characteristics of partial edentulous patients who no longer wear their dentures, explore their reasons, and assess their oral health-related quality of life (OHRQoL). METHODOLOGY: This cross-sectional study, conducted at Chulalongkorn University Dental School from 2013 to 2019, involved patients who received PRDP treatment. They were contacted via phone calls and asked about their denture usage. Eligible participants were patients who had stopped or rarely used their PRDPs. Data on oral status, health insurance, and PRDP variables were collected from hospital records. Telephone interviews were conducted to collect the initial reasons for seeking PRDP treatment, reasons for discontinuation, desire for a new PRDP, and OHRQoL. The Oral Impacts on Daily Performances index was used to assess the OHRQoL. The score was dichotomized into the absence or presence of oral impacts. Chi-square tests and multivariable binary logistic regression were employed to determine the associations between oral impacts and various factors in the participants who discontinued PRDP usage. RESULTS: Among the 975 contacted participants, 175 (17.9%) discontinued using their PRDPs. Most of these individuals had at least 20 remaining natural teeth and/or 4 posterior occluding pairs. The primary initial reason for seeking PRDP treatment was often based on a dentist's suggestion. Although many participants reported no impact on OHRQoL and did not express the need for new PRDPs, those experiencing oral impacts were more likely to seek replacements. CONCLUSIONS: With up to 7 years follow-up duration, individuals with partial edentulism and sufficient remaining functional dentition without oral impacts were more inclined to discontinue PRDP usage. Those with maxillary anterior teeth loss were less likely to discontinue using their PRDP. The primary initial reason for seeking PRDP treatment was often a dentists' suggestion. However, the individuals reporting oral impacts expressed their needs for new denture replacements. This highlights the significance of incorporating patient needs and preferences in prosthodontic decision-making.

Clinical Measurements of Force Exerted on Anterior Teeth in Partial Edentulous Distal Extension.

PURPOSE: To determine the influence of partial edentulous distal extension and the use of removable partial dental prostheses in partially edentulous areas on the force exerted on the anterior teeth. MATERIALS AND METHODS: A total of 83 volunteer patients participated in this study. The occlusal force was measured using an occlusal force measuring sheet in the patient's mouth. The occlusal forces and ratios were compared using the Wilcoxon signed-rank test (P < .05). RESULTS: The force exerted on the anterior teeth increased significantly as the number of remaining teeth decreased in an edentulous distal extension. The force exerted on the anterior teeth decreased significantly with the use of a removable partial dental prosthesis. CONCLUSIONS: In a clinical setting, when the number of remaining teeth in a partial edentulous distal extension decreases, the burden on the anterior teeth increases. Our findings suggest that, for patients with partial edentulous distal extension, using a removable partial dental prosthesis is effective in preserving the residual anterior teeth by reducing excessive force.

Digital planning and surveying for a rotational path removable partial denture: a case report.

Digital technology has been applied to the planning and manufacture of removable partial dentures (RPDs), reducing the complexity of RPD treatment as well as the number and duration of clinical and laboratory steps. However, there is a lack of information regarding digital planning and surveying for rotational path RPDs. This article presents a case report of a digital diagnostic wax-up and survey for a rotational path RPD performed with prosthetic design software. The virtual diagnostic closure tool made it possible during the case study stage to visualize the edentulous spaces and simulate the preparations necessary for the restoration of occlusal and esthetic harmony. The virtual survey determined the dual-axis path of insertion and removal for the rotational path RPD based on the 4 major influencing factors: guiding planes, retentive undercuts, interferences, and esthetics. In this case, digital planning and surveying for a rotational path RPD were an effective means of esthetic and biomechanical analysis and allowed for minimal preparation of the abutment teeth.

Evaluation of two printing techniques for maxillary removable partial denture frameworks.

STATEMENT OF PROBLEM: Three-dimensional (3D) printing technology has gained popularity in producing removable partial denture (RPD) frameworks, including direct 3D printing of the metal framework and framework printing using castable resin, subsequently cast and processed. However, whether the technology is sufficiently accurate and precise to supersede traditional methods is unclear. PURPOSE: The purpose of this in vitro study was to determine the accuracy and precision of 2 different methods in the fabrication of RPD frameworks, including 3D printing by selective laser melting (SLM) and digital light processing (DLP). MATERIAL AND METHODS: Maxillary casts were digitized to design RPD frameworks. Thereby, 8 frameworks were produced for each group. The SLM group underwent a thermal finishing process after printing. In the DLP group, castable resin was printed but not cast. All frameworks were scanned to generate digital files, which were then compared with the original design using a metrology software program and manual measurements. Statistical analysis was executed using the t-test for independent specimens (α=.05) and by comparing heatmaps of the overlaid meshes. RESULTS: The analysis of the frameworks indicated minor deviations across all specimens. Regarding accuracy, there were no significant differences between the groups (P=.986). The SLM frameworks demonstrated greater precision, with absolute deviation values of 0.13 mm compared with 0.17 mm in the DLP group (P<.001). CONCLUSIONS: The findings underscored a high consistency between the 2 printing techniques, demonstrating a sufficiently advanced production process to yield predictable results. While the accuracy of both techniques was at a comparably high level and did not differ significantly, the SLM technique delivered RPDs with higher precision.

An in vitro assessment of optimizing implant positions in bilateral distal extension implant-assisted removable partial dentures: A microstress analysis.

AIM: The aim of this study was to analyze and compare the stress distribution on dental implants in various positions when used with implant-assisted removable partial dentures. SETTINGS AND DESIGN: This was an in vitro study. MATERIALS AND METHODS: A model representing a mandibular bilateral partially edentulous condition, with missing premolars and molars, was fabricated using epoxy resin. Two implants of similar diameter measuring 4.0 mm × 10 mm (Dentium, Korea) were inserted in the second molar and the second premolar region on either side of the model for comparing the biomechanical effect of various implant locations. Two types of loads 100N and 125N were applied vertically using universal testing machines in the premolar and molar regions. The loads on the implants beneath the cast partial denture were measured by physical stress analysis using a microstrain gauge. STATISTICAL ANALYSIS USED: A comparison of maximum stress observed at the premolar versus molar regions due to the application of the 100N and 125N loads was done using the Mann-Whitney U-test. RESULTS: In physical stress analysis, obtained results were statistically analyzed, and the result was statistically not significant (P = 0.435 at 100N and P = 0.718 at 125N) in positional changes of implant. CONCLUSION: In the current study, the statistical analysis of physical stress revealed no significant differences in stress values between the loadings at the premolar and molar regions. This suggests that the implant can be placed in either the premolar or molar region based on the availability of bone without affecting stress distribution.

Implant-assisted removable partial dentures: Part I. a scoping review of clinical applications.

PURPOSE: This scoping review aimed to systematically map research regarding implant-assisted removable partial dentures (IARPDs), and identify existing gaps in knowledge. STUDY SELECTION: Two reviewers independently conducted a search of the MEDLINE-PubMed and Scopus databases according to the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) extension for Scoping Review and included articles published in English up to August 31, 2022, including human studies, reviews, and in vitro studies. Expert opinions, animal studies, and clinical studies involving complete overdentures were excluded, and ten aspects for establishing the treatment strategy for IARPDs were examined. RESULTS: One hundred and twelve articles were chosen. There were two treatment modalities: IARPDs retained by implant- and tooth-supported surveyed single crowns (SCs) or fixed partial dentures (FPDs). In IARPDs retained by tooth-supported surveyed SCs or FPDs, the survival rate of dental implants for IARPDs was relatively higher with a wide range of marginal bone loss and many complications, but with improved functional performance, oral health-related quality of life, and patient satisfaction. There were limited data on survival or success rates and designs of IARPDs, attachment selections, length and diameter, inclination, placement sites, and loading protocols of implants, regardless of prosthetic types. There was limited information on maxillary IARPDs except for survival rates of implants. CONCLUSIONS: Although IARPDs could become a useful treatment strategy, there is limited scientific consensus with gaps in knowledge about their use. Additional well-designed clinical and in vitro studies are necessary to scientifically establish IARPDs as definitive prostheses in implant dentistry.

Clinical evaluation of removable partial dentures with digitally fabricated metal framework after 4 years of clinical service.

This case report describes the clinical outcomes of three patients who received removable partial dentures with a completely digitally designed and manufactured metal framework. The initial intraoral impressions were prepared, and the resulting standard tessellation language files were sent to a dental laboratory, where the alloy framework was designed using inLab software and printed using a 3D printer or milled directly from a Co-Cr disc. The quality of fit of the framework was evaluated intraorally to confirm the laboratory design. The acrylic teeth were set, and the definitive partial dentures were delivered after the acrylic resin bases were processed. The follow-up time was 4 years. No complications or failures related to the components of the partial dentures were observed.

Comparison between digital superimposition and microcomputed tomography methods of fit assessment of removable partial denture frameworks.

STATEMENT OF PROBLEM: The fit of removable partial denture frameworks should be assessed to optimize clinical adaptation. Potential discrepancies between framework and supporting structures are typically precisely measured with negative subtracts and high-resolution equipment. The growth of computer-aided engineering technology allows the development of new methods for the direct evaluation of discrepancies. However, how the methods compare is unclear. PURPOSE: The purpose of this in vitro study was to compare 2 digital methods of fit assessment based on direct digital superimposition and microcomputed tomography indirect analysis. MATERIAL AND METHODS: Twelve cobalt chromium removable partial denture frameworks were fabricated by conventional lost-wax casting or additive manufacturing techniques. The thickness of the gap between occlusal rests and respective definitive cast rest seats (n=34) was evaluated by using 2 different digital methods. Silicone elastomer impressions of the gaps were obtained, and microcomputed tomography measurements were used as controls for validation purposes. Digitization of the framework, the respective definitive cast, and the combination was followed by digital superimposition and direct measurements with the Geomagic Control X software program. Because normality and homogeneity of variance were not verified (Shapiro-Wilk and Levene tests, P<.05), the data were analyzed with Wilcoxon signed rank and Spearman correlation tests (α=.05). RESULTS: The thicknesses measured by microcomputed tomography (median=242 µm) and digital superimposition (median=236 µm) did not reveal statistically significant differences (P=.180). A positive correlation (ρ=0.612) was detected between the 2 methods of assessing fit. CONCLUSIONS: The frameworks presented median gap thicknesses under the limit of clinical acceptability without differences between the proposed methods. The digital superimposition method was determined to be as acceptable as the high-resolution microcomputed tomography method for assessing removable partial denture framework fit.

Minimal invasive prosthetic rehabilitation of a patient with Down syndrome: A case report.

INTRODUCTION: Down syndrome (DS), an easily recognized congenital disease, is associated with a high prevalence of dental anomalies. Therefore, special dental care is required. CASE PRESENTATION: This case report described the minimally invasive prosthetic rehabilitation of a 31-year-old female patient with DS. Prompt diagnosis, consultation with physicians and family, and accurate medical history were needed, and relevant dental, medical, mental, and behavioral factors were considered. A minimally invasive treatment plan was decided after clinical examination, orthopantomography (OPG), and study model analysis. For the upper jaw, an over denture was constructed. For the lower jaw, a simple metal-frame partial denture was made. This treatment plan was decided after considering the difficulty in dentist-patient collaboration and a small maxilla with poor positioning of teeth and negative overbite and over jet. CONCLUSION: Considering different patient factors including patient cooperation, as well as the medical and dental conditions associated with DS, a minimally invasive prosthodontic treatment option was recommended.

Evaluation of the Empower model of care for partial denture clients in a public oral health care setting.

OBJECTIVE: To evaluate the effectiveness of the Empower model of care (EMC) on reducing the addition of teeth to removable partial dentures (RPD). METHODS: Data reports were generated through the Titanium electronic database to retrieve all clients at Monash Dental Services (MHDS) who participated in the EMC or received an RPD prior to the implementation of EMC was assessed over a two-year period to determine if they had additional teeth added to their partial dentures (PD). A logistic regression was performed testing whether a combination of socio-demographic and clinical variables, provided a multivariate explanation of the EMC outcome. RESULTS: Prior to EMC, 2034 patients attended MHDS requiring RPDs with 363 returning to have teeth added. From 2018 to 2020, 38 of 584 participants in EMC returned to have teeth added to their PDs. Those in the 'High' risk group were two times more likely to return requiring additional teeth (OR = 1.99; 95%CI:1.31-3.02); each additional year of age increased the odds of requiring additional teeth (OR = 1.03; 95%CI:1.02-1.04). Participants of the EMC were more than two times less likely to require additional teeth (OR = 0.42; 95%CI:0.29-0.59). The variance in requiring additional teeth accounted for using the full model was 9.1% (η2 = 0.091). CONCLUSIONS: This analysis confirms the effectiveness of the EMC. This approach assists denture wearers to maintain good oral health and provides an effective way of managing public health funds by reducing denture repairs and additions. © 2023 Australian Dental Association.

Comparative analysis of the retention force and deformation of PEEK and PEKK removable partial denture clasps with different thicknesses and undercut depths.

STATEMENT OF PROBLEM: The retentive force and deformation of milled polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) removable partial denture (RPD) frameworks are not well understood. PURPOSE: The purpose of this in vitro study was to assess the retentive force and deformation of PEEK and PEKK Akers clasps with different designs and undercut depths. MATERIAL AND METHODS: A master model containing the first and second molar abutments was used to design Akers clasps of different cross-sectional dimensions, undercut depths (0.5 and 0.75 mm), and materials. The components of the removable partial denture framework also included an occlusal rest and were manufactured using a milling machine (n=5). The fatigue resistance of the Akers clasps was measured before and after deformation regarding the retentive forces. RESULTS: The PEEK2-U50 clasp had the largest retentive force with no significant difference among all groups before and after the insertion and removal cycle. In addition, the increased cross-sectional dimensions of the design resulted in significant differences in retentive forces between the PEEK1 and PEEK2 groups and between the PEEK and PEKK materials. CONCLUSIONS: Increasing the clasp's cross-sectional dimensions significantly impacted retentive forces, especially between different PEEK groups and between PEEK and PEKK materials.

Implant-assisted removable partial dentures: Part II. a systematic review of the effects of implant position on the biomechanical behavior.

PURPOSE: This systematic review aimed to evaluate the effects of implant placement sites on the biomechanical behavior of implant-assisted removable partial dentures (IARPDs) using finite element analysis (FEA). STUDY SELECTION: Two reviewers independently conducted manual searches of the PubMed, Scopus, and ProQuest databases for articles investigating implant location in IARPDs using FEA, according to the 2020 Systematic Reviews and Meta-analyses statement. Studies published in English up to August 1, 2022, were included in the analysis based on the critical question. RESULTS: Seven articles meeting the inclusion criteria were systematically reviewed. Six studies investigated mandibular Kennedy Class I and one study investigated mandibular Kennedy Class II. Implant placement reduced the displacement and stress distribution of the IARPD components, including dental implants and abutment teeth, regardless of the Kennedy Class type and dental implant placement site. Most of the included studies showed that, based on the biomechanical behavior, the molar region, rather than the premolar region, is the preferred implant placement site. None of the selected studies investigated the maxillary Kennedy Class I and II. CONCLUSIONS: Based on the FEA regarding mandibular IARPDs, we concluded that implant placement in both the premolar and molar regions improves the biomechanical behaviors of IARPD components, regardless of the Kennedy Class. Implant placement in the molar region results in more suitable biomechanical behaviors compared with implant placement in the premolar region in Kennedy Class I. No conclusion was reached for Kennedy Class II due to the lack of relevant studies.

Accuracy and surface roughness of Co-Cr partial denture frameworks with different digital fabrication methods.

STATEMENT OF PROBLEM: Traditional removable partial denture (RPD) manufacture is being phased out in favor of computer-aided design and computer-aided manufacturing (CAD-CAM) techniques and rapid prototyping (RP), which provide more efficient methods of producing RPD frameworks. However, studies comparing the accuracy and surface roughness of these approaches on RPD frameworks are still scarce. PURPOSE: The purpose of this in vitro study was to evaluate the accuracy and surface roughness of class I cobalt chromium (Co-Cr) removable partial denture frameworks digitally constructed using 2 different CAD-CAM technologies: direct milling (DM) and selective laser melting (SLM). MATERIAL AND METHODS: An educational maxillary stone cast was scanned to create a resin model after rest seat preparation. The resin model was scanned, and an RPD framework was digitally designed. Sixteen frameworks were constructed (n=8). Two groups were defined. In the direct milling (DM) group, the standard tessellation language (STL) file of the RPD framework was used to mill the design from a Co-Cr blank directly. In the selective laser melting (SLM) group, the STL file of the RPD framework was used to print the design from Co-Cr powder using the selective laser melting technique. Geomagic Control X software program was used to measure the accuracy of the fabricated frameworks. Surface roughness was tested using optical profilometry. An unpaired t test was used to compare the 2 groups (α=.05). RESULTS: The DM group showed significantly higher mean ±standard deviation accuracy (189 ±9 µm) (P<.001) compared with the SLM group (456 ±122 µm). Regarding the surface roughness, the DM group (0.157 ±0.001 mm) showed significantly lower surface roughness (P<.001) compared with the SLM group (0.256 ±0.001 mm). CONCLUSIONS: The direct milling fabrication technique enabled the fabrication of Co-Cr RPD frameworks with higher accuracy and less surface roughness when compared with the 3-dimensionally printed SLM technique.

Antimicrobial activity of cleansers on the cobalt-chromium surface of removable partial denture: a systematic review.

This study aimed to review systematically the literature about the antimicrobial action of evaluated cleansers on the Co-Cr alloy of RPD. The search was conducted in MEDLINE/PubMed, Scopus, Lilacs, Embase and Science Direct May, 2022. The review was performed based on PRISMA guidelines and recorded in Open Science Framework. Independent reviewers performed the search, selection, extraction, and analysis of the data. The risk of bias of the in vitro and clinical trials studies was analyzed by the Joanna Briggs Institute tool. A total of 187 articles were found and 9 were included. The cleansers that showed antimicrobial action were 2% and 5.25% sodium hypochlorite, 0.12% chlorhexidine and NitrAdine effervescent tablet. Polident, Corega Tabs effervescent tablets and 5 mg/mL chitosan solution showed intermediate effects. Propolis and green tea toothpaste were not effective. Three articles presented a high risk of bias and 6, low risk. The cleansers that showed the highest antimicrobial efficacy on Co-Cr alloy were 0.12% chlorhexidine digluconate and NitrAdine and can be safely used on RPD framework.

Removable Partial Denture - Functional Impression Techniques: Review.

The objective of this article is to concisely review the main clinical techniques used to make the functional impression to manufacture a removable partial denture. Through this review, the dentist can develop his clinical knowledge.

A Preliminary Study on the Accuracy of Cast Metal Removable Partial Denture Frameworks Produced from Wax, Printed, and Milled Patterns

PURPOSE: To compare the accuracy of two digital workflows for producing resin patterns to be cast into metal frameworks compared to an identical framework manufactured conventionally from a wax pattern. MATERIALS AND METHODS: Nine casts were duplicated from a maxillary master cast of a partially edentulous arch. Their accuracy was determined by measuring the same points in two and three dimensions using a reflex microscope, which was also used to measure all frameworks to an accuracy of 4 µm. The same design was used throughout. Three casts were used to make a framework conventionally from an invested wax pattern. Six casts were scanned, and a digital pattern created. Three patterns were milled from a resin block, and three were 3D printed with resin. Then each pattern was cast. RESULTS: The sample size precluded direct statistical conclusions, but no significant differences were found. Duplicate models showed minimal differences compared to the master cast. All patterns and all frameworks showed some level of difference compared to the master cast, but no differences were greater than those reported in the literature as being clinically acceptable. The maximum overall discrepancy between the cast frameworks was 0.64 mm, and at the rest seats was 0.262 mm. CONCLUSION: Within the limitations of this study, given the very small actual differences both within and between the groups of the three different workflows, the use of digitally produced resin patterns prior to their being cast as metal frameworks is both feasible and well within the accepted limits for clinical acceptability.

Comparación de prótesis removibles parciales y totales entregadas según sus características clínicas en el servicio de odontología del hospital nacional de geriatría y gerontología, en el período de tiempo comprendido del 1 de enero 2005 al 31 de diciembre del 2008 / Comparison of partial and total removable prosthesis delivered according to their clinical characteristics in the dentistry service of the national hospital of geriatry and gerontology, in the period under january 1 of 2005 to december 31 of 2008

RESUMEN Objetivo: Comparar la cantidad y características de las prótesis dentales removibles parciales y totales, en el servicio de odontología del Hospital Nacional de Geriatría y Gerontología, en el periodo de tiempo comprendido del 1 de enero 2005 al 31 de diciembre 2008, equivalentes a 326 expedientes. Se tomó la base de datos del servicio de odontología de consulta externa especializada de los pacientes atendidos de los años 2005 al 2008, en los cuales se entregaron un total de 2786 prótesis dentales removibles. Materiales y métodos: Con base en el dato anterior se seleccionó la muestra no aleatoria a conveniencia hasta alcanzar el tamaño de 599 prótesis entregadas, examinando 326 expedientes del periodo de enero del 2005 a diciembre del 2008, con un nivel de confianza de 99% y un error de muestreo de 0.0466. La recolección de datos se realizó por medio del programa Microsoft Excel donde se utilizó una tabla en la que se anotó el número de expediente, fecha de inicio y conclusión de prótesis, tipo de prótesis, cantidad y color de prótesis, edad, género y domicilio del paciente por distrito, cantón y provincia. El procesamiento se realizó por medio de estadística descriptiva utilizando cuadros y gráficos. Resultados: Se determinó que el mayor porcentaje de rango de edad de personas que solicitaron prótesis removibles fue de 62 a 65 años, independiente si eran prótesis totales o parciales, los pacientes que requirieron dos prótesis fueron 273 de 326, en su mayoría los pacientes solicitaron prótesis totales para un total de 372 de 599 prótesis entregadas. De la guía de color utilizada en el HRBC los colores más requeridos fueron los tonos claros blanco amarillentos que corresponde al número 62 y 65; de los expedientes analizados la mayoría de los pacientes residían en San José con un total de 200 pacientes. Se concluye que el mayor porcentaje de edentulismo que se presento es el edentulismo total con un 62%, la prótesis más utilizada es la prótesis total superior removible y en su mayoría los pacientes requieren dos prótesis, con respecto al color no es concluyente para este estudio debido a los datos no disponibles en los expedientes analizados.

ABSTRACT Objective: Compare the quantity and characteristics of partial and total removable dental prostheses, in the dentistry service of the National Hospital of Geriatrics and Gerontology, in the period from January 1, 2005 to December 31, 2008. The database of the specialized outpatient dentistry service of the patients treated from 2005 to 2008 was taken, in which a total of 2786 removable dentures were delivered. Materials and methods: Based on the previous data, the non-random sample was selected for convenience until reaching the size of 599 protheses of 326 files, with a confidence level of 99% and a sampling error of 0.0466. Data collection was carried out through the Microsoft Excel program where a table was used in which the file number, date of start and conclusion of the prosthesis, type of prosthesis, amount and color of prosthesis, age, gender and address were used of the patient by district, canton and province. The processing was carried out by means of descriptive statistics using tables and graphs. Results: It was determined that the highest percentage of the age range of people who requested removable prostheses was 62 to 65 years, the patients that required two prostheses were 273 of 326. In their majority, the patients requested total prostheses for a total of 372 of 599 prostheses delivered. Of the color guide used in the HRBC, the most requested colors were the light yellowish-white tones corresponding to the number 62 and 65; of the files analyzed, most of the patients resided in San José with a total of 200 patients. Conclusion: It is concluded that the highest percentage of edentulism that is presented is total edentulism with 62%, the most commonly used prosthesis is the removable upper total prosthesis and for the most part patients require two prostheses, with respect to color it is inconclusive for this study due to data not available in the analyzed files.

Success and complication rates of non-precious alloy telescopic crowns in a general dental practice.

OBJECTIVES: This retrospective, single-center, practice-based cohort study aimed to analyze factors associated with the success of removable partial dentures retained by telescopic crowns (TRPD). MATERIALS AND METHODS: TRPD which were placed in a single practice of a practice-based research network were analyzed. Data from 139 patients (age (SD): 66 (11) years; 66 female) with 174 TRPD including 488 non-precious alloy telescopic crowns (TC) between 2004 and 2016 were included. TC without any technical complication were considered as successful, and as survived, if they were still in function at the last check-up. Multilevel Cox proportional hazard models were used to evaluate the association between clinical factors and time until failure. RESULTS: Within a mean follow-up period (SD) of 4.2 (3.3) years (min-max: 1 day-12 years), 372 (76%) TC (AFR5years,TC-level: 5.0%) as well as 136 (87%) TRPD (AFR5years,TRPD-level: 5.1%) ("worst-case scenario") and 150 (86%) TRPD (AFR5years,TRPD-level: 3.4%) ("best-case scenario") were considered as successful. The main failure types were recementation (n = 39), endodontic treatment (n = 36), and extraction (n = 35). TC in male patients showed 1.6 times higher risk for failure than in female patients (95%CI: 1.1-2.4; p = 0.023). TC on premolars showed 2.2 times higher risk for failure than on incisors (95%CI: 1.1-5.0; p = 0.023) and TC in dentures with ≤ 3TC showed 2.1 times higher risk for failure than TC in dentures with > 3TC (1.3-3.4; p = 0.042). Furthermore, TC on the most distal tooth in an arch showed 2.4 times higher risk for failure than TC on a more mesial tooth (1.5-3.8; p < 0.001). CONCLUSION: For removable partial dentures retained by telescopic crowns, high success rates could be found after up to 12 years. Patient-level and tooth-level factors were significantly associated with failure. CLINICAL RELEVANCE: For removable partial dentures retained by telescopic crowns, high success rates could be found after up to 12 years. Patient-level and tooth-level factors were significantly associated with failure.