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International Journal of Implant... Oct 2020Implant-supported removable partial dentures (ISRPDs) are an effective treatment for partially edentulous patients. ISRPDs improve patients' satisfaction and oral...
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.
PubMed: 33089410
DOI: 10.1186/s40729-020-00260-4 -
European Journal of Dentistry Feb 2022The aim of the study was patients' satisfaction evaluation and radiographic evaluation of the terminal abutments of attachment-retained maxillary obturators with...
OBJECTIVE
The aim of the study was patients' satisfaction evaluation and radiographic evaluation of the terminal abutments of attachment-retained maxillary obturators with metal framework versus milled polyetheretherketone (PEEK) framework in the management of maxillectomy cases.
MATERIALS AND METHODS
Eighteen participants were randomly divided into three parallel groups ( = 6). Participants of the PEEK group received attachment-retained obturators with milled PEEK framework, the metal group received an attachment-retained obturator with a metallic framework, and the conventional group received conventional clasp-retained obturators with a metallic framework (Control group). The evaluation included was radiographic evaluation and patients' satisfaction in this study included two scales-"The Obturator Functioning Scale" and "The European Organization for Research and Treatment of Cancer Head and Neck 35" using one-way ANOVA test.
RESULTS
Both PEEK and metal groups showed a statistically significant lower mean bone loss ( <0.050) compared with the conventional group during all follow-up periods. There is no statistically significant difference between the PEEK and metal groups during all follow-up periods. Regarding patient satisfaction, both the PEEK and metal groups showed a statistically significant decrease score ( <0.050) compared with the conventional group in various aspects of patients' satisfaction scales as satisfaction with the look and difficulty of talking to the public, and noticeable clasps. In comparison, the PEEK group showed a statistically significant decrease score ( <0.050) than the metal group with respect to satisfaction with the look along all follow-up periods.
CONCLUSIONS
PEEK attachment-retained maxillary definitive obturators could be considered a promising treatment modality for patients with acquired maxillary defects with regard to esthetics and satisfaction.
PubMed: 34814222
DOI: 10.1055/s-0041-1731839 -
Clinical, Cosmetic and Investigational... 2021This clinical report describes a technique for fabricating a retrofit zirconia crown and clasp for an existing removable partial denture (RPD) using computer-aided...
This clinical report describes a technique for fabricating a retrofit zirconia crown and clasp for an existing removable partial denture (RPD) using computer-aided design and computer-aided manufacturing (CAD/CAM). A 58-year-old patient developed acute pulpitis of a tooth, and the RPD clasp was broken on the tooth. A pre-preparation scan was captured using an intraoral scanner. The existing RPD was placed in the mouth, and scans of the post-preparation, antagonist arch, and interocclusal record were made. A zirconia crown was designed by superimposing the pre-preparation scan and the post-preparation scan of the abutment tooth. The design data were transferred to a 5-axis milling machine, and the crown was milled from zirconia. The crown was luted using resin cement. An intraoral scan of the crown with RPD was taken, and the RPD was removed to re-scan the proximal guide plane of the crown. The I-bar clasp was designed, and the casting pattern was built using a 3D printer. The pattern was used to cast the clasp. The clasp was set using autopolymerizing acrylic resin to the RPD. The main advantages of this efficient process are that patients can use their RPDs during fabrication of the crown of the abutment tooth. The limitations of using this technique include the cost of the intraoral scanner and the education for the dental clinicians and technicians. In this clinical report, CAD/CAM technology prevented human error, required no adjustment, and uninterrupted use of the RPD for fabricating a retrofit zirconia crown and clasp for an existing RPD.
PubMed: 34675685
DOI: 10.2147/CCIDE.S332944 -
Journal of Prosthodontic Research Oct 2023Although digital removable partial dentures have been previously described, there have been no reports on how to fabricate them in one piece. This study proposes a new...
PURPOSE
Although digital removable partial dentures have been previously described, there have been no reports on how to fabricate them in one piece. This study proposes a new method for fabricating patient-specific digital removable partial dentures using a custom plate.
METHODS
First, a gypsum model was scanned using a laboratory scanner and a removable partial denture was designed using computer-aided design (CAD) software based on standard tessellation language data. The metal clasp was fabricated from Ti-6Al-4V using a 3D printer. For custom plate fabrication, a resin plate frame was designed using computer-aided design (CAD) software and fabricated using a 3D printer. An artificial tooth and metal clasp were fixed on the base surface of the frame, an auto-polymerizing resin was poured into the frame for the denture base, and the artificial tooth and metal clasp were packed to form a custom plate. The plate was cut using a milling machine. Subsequently, the support attached to the denture was removed and polished for complete fabrication of the denture.
CONCLUSIONS
Our novel removable partial denture fabrication method is more efficient than the conventional method. The obtained removable partial dentures demonstrated satisfactory accuracy.
PubMed: 36725080
DOI: 10.2186/jpr.JPR_D_22_00100 -
The Journal of Clinical Pediatric... 2016Lab appliances are an integral part of orthodontics, from active treatment to retention. The quality and fit of an appliance can affect the treatment result and...
UNLABELLED
Lab appliances are an integral part of orthodontics, from active treatment to retention. The quality and fit of an appliance can affect the treatment result and stability.
AIMS
This study aims to determine common points of failure in orthodontic appliances, and suggest methods to reduce this rate.
METHODS
A survey consisting of 23 questions was distributed to active members of the American Association of Orthodontists (AAO) via Survey Monkey.
RESULTS
The most common appliance to need an adjustment was the wrap-around retainer, with the Hawley retainer as a close second. The least common appliance needing adjustment was the Essix/clear retainer. Respondents were asked which component of each appliance was most commonly responsible for an ill-fit. For Hawley and wrap-around retainers, clasps were the most common problem at 50%, whereas spring aligners had two components - clasps and labial bows, both at 38%. Ill-fitting Essix/clear retainers had gingival impingement (52%) closely followed by poor posterior seating (43%).
CONCLUSIONS
Communication between the orthodontist and lab technician can be improved by establishing a quality assurance protocol for outgoing and incoming cases. The labial bow of Hawley's, wrap-arounds and spring aligners should be clearly demarcated on the casts. Impressions should be free of distortion and casts should be inspected for accuracy. Clear retainers and positioner should be trimmed to avoid gingival impingement. The type of clasp should be selected based on the anatomy of the teeth, and bands should be checked for accuracy of fit.
Topics: Dental Technicians; Dentists; Humans; Interprofessional Relations; Laboratories, Dental; Orthodontic Appliance Design; Orthodontic Appliances; Orthodontic Retainers; Quality Control
PubMed: 27805883
DOI: 10.17796/1053-4628-40.6.506 -
BMC Oral Health Sep 2023Digital technologies have recently been introduced into the fabrication of removable partial dentures (RPDs). However, it is still unclear whether the digitally... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Digital technologies have recently been introduced into the fabrication of removable partial dentures (RPDs). However, it is still unclear whether the digitally fabricated RPDs fit better than conventionally cast ones in the rest region. The aim of this study was to evaluate the fit accuracy in the rest region of RPDs fabricated by digital technologies and compare it to those made by conventional lost-wax (CLW) technique.
METHODS
A comprehensive search was conducted in Cochrane Library, PubMed, EMbase, Web of Science and SpringerLink. Studies published up to August 2022 were collected. Two authors analyzed the studies independently and assessed the risk of bias on the modified methodological index for non-randomized studies (MINORS) scale. The mean values of gap distance between rests and corresponding rest seats of each study were extracted as outcome. A random-effects model at a significance level of P < 0.05 was used in the global comparison and subgroup analysis was carried out.
RESULTS
Overall, 11 articles out of 1214 complied with the inclusion criteria and were selected, including 2 randomized controlled trials (RCTs), 1 non-randomized clinical trial and 8 in vitro studies. Quantitative data from Meta-analysis revealed that fit accuracy in the rest region of RPDs fabricated with CLW showed no statistically significant difference with digital techniques (SMD = 0.33, 95%CI (-0.18, 0.83), P = 0.21). Subgroup analysis revealed a significantly better fit accuracy of CLW-fabricated RPDs in the rest region than either additive manufacturing (AM) groups or indirect groups (P = 0.03, P = 0.00), in which wax or resin patterns are milled or printed before conventional casting. While milled RPDs fit significantly better than cast ones in the rest region (P = 0.00). With digital relief and heat treatment, hybrid manufactured (HM) clasps obtained better fit accuracy in the rest region (P < 0.05). In addition, finishing and polishing procedure had no significant influence in the fit accuracy in all groups (P = 0.83).
CONCLUSIONS
RPDs fabricated by digital technologies exhibit comparable fit accuracy in rest region with those made by CLW. Digital technologies may be a promising alternative to CLW for the fabrication of RPDs and additional studies are recommended to provide stronger evidence.
TRIAL REGISTRATION
CRD42020201313.
Topics: Humans; Denture, Partial, Removable; Digital Technology; Research Design; Rest; Dental Casting Technique
PubMed: 37715159
DOI: 10.1186/s12903-023-03348-6 -
PloS One 2021Flipped classroom may overcome weaknesses of live demonstration in teaching orthodontic wire-bending. This study aims to compare the effectiveness between flipped...
Flipped classroom may overcome weaknesses of live demonstration in teaching orthodontic wire-bending. This study aims to compare the effectiveness between flipped classroom and live demonstration in transferring skills for fabricating Adams clasp. Forty third-year undergraduate dental students were assigned to two groups. The students in group LD (n = 20) attended a live demonstration while students in group FC (n = 20) attended a flipped classroom. Both groups were taught on skills to fabricate Adams clasp in a standardised way. Each student from both groups were asked to submit an Adams clasp for a blinded quality assessment by two trained and calibrated assessors using a 18-item rubric, followed by validated students' satisfaction questionnaires to evaluate their perceived satisfaction on the teaching method received. A crossover study was then conducted three weeks later where LD attended a flipped classroom while FC attended a live demonstration. Students' satisfaction questionnaires were again collected from each student for blinded analysis. Mean scores for the quality of Adams clasp were 9.775 and 9.125 for LD and FC, respectively. No significant difference was detected between the two groups. Statistically significant association was found for one statement on the questionnaire, "I found the classroom arrangements conducive for the wire-bending activity" (p = 0.010). No significant differences were found between the two groups for other statements (p > 0.05). In conclusion, within the limitations of the study, flipped classroom is equally effective as conventional live demonstration in transferring orthodontic wire-bending skills for fabrication of Adams clasp. However, students perceived the classroom arrangements during the flipped classroom significantly more conducive for teaching orthodontic wire-bending.
Topics: Cross-Over Studies; Female; Humans; Male; Orthodontic Wires; Problem-Based Learning; Surveys and Questionnaires
PubMed: 34243187
DOI: 10.1371/journal.pone.0254478 -
European Journal of Dentistry 2017The purpose of this study was to investigate the importance of environments (dry and wet) to dislodge the clasp.
OBJECTIVE
The purpose of this study was to investigate the importance of environments (dry and wet) to dislodge the clasp.
MATERIALS AND METHODS
Mandibular test models with natural premolar and molar teeth were used to test four types of clasp (each 12) (Akers, rest plate Akers [RPA], half and half [H-H], and ring clasp) in dry and natural fresh saliva environments. Each clasp was pulled out 10 times with a crosshead speed of 10 mm/min and the force required to withdraw each was measured.
STATISTICAL ANALYSIS USED
A paired sample -test and Wilcoxon test were used.
RESULTS
There were significant differences between the dry and wet (natural fresh saliva) environment. However, while the mean of the environment for RPA and ring clasp type was significantly different, the H-H and Akers clasp type was not.
CONCLUSION
The environment has an effect on dislodging the clasp but differs according to the type of clasp.
PubMed: 28932146
DOI: 10.4103/ejd.ejd_158_17 -
Journal of Prosthodontic Research Jan 2014This position paper proposes a definition and naming standard for removable partial dentures (RPDs) using thermoplastic resin, and presents a guideline for clinical... (Review)
Review
This position paper proposes a definition and naming standard for removable partial dentures (RPDs) using thermoplastic resin, and presents a guideline for clinical application. A panel of 14 experts having broad experience with clinical application of RPDs using thermoplastic resin was selected from members of the Japan Prosthodontic Society. At a meeting of the panel, "non-metal clasp denture" was referred as the generic name of RPDs with retentive elements (resin clasps) made of thermoplastic resin. The panel classified non-metal clasp dentures into two types: one with a flexible structure that lacks a metal framework and the other having a rigid structure that includes a metal framework. According to current prosthetic principles, flexible non-metal clasp dentures are not recommended as definitive dentures, except for limited cases such as patients with a metal allergy. Rigid non-metal clasp dentures are recommended in cases where patients will not accept metal clasps for esthetic reasons. Non-metal clasp dentures should follow the same design principles as conventional RPDs using metal clasps.
Topics: Contraindications; Dental Clasps; Denture Design; Denture Retention; Denture, Partial, Removable; Humans; Metals; Resins, Synthetic
PubMed: 24461323
DOI: 10.1016/j.jpor.2013.12.002 -
Journal of Oral & Maxillofacial Research 2016Dentures are worn by around 20% of the population, yet if they become displaced they may enter the gastrointestinal or respiratory system, sometimes with grave... (Review)
Review
OBJECTIVES
Dentures are worn by around 20% of the population, yet if they become displaced they may enter the gastrointestinal or respiratory system, sometimes with grave consequences. The aim of this study was to review recent published literature in order to identify the epidemiology of patients and characteristics of swallowed and aspirated dental prostheses, and propose strategies to minimise these risks.
MATERIAL AND METHODS
A fifteen year retrospective of published case series and case reports was carried out. Photographs, radiographs and descriptions of the dental prostheses were gathered, as well as the patient's presenting complaint, the anatomical site where the denture was caught and the procedure required to remove the denture.
RESULTS
Ninety one separate events of swallowed or aspirated dentures were identified from 83 case reports and series from 28 countries. Average age was 55 years, and these were 74% male. Photographs were retrieved for 49 of these dentures. Clasps were present in 25 of the dentures. There was no significant difference between clasped and unclasped dentures for perforation rates, need for open surgery and spontaneously passed dentures.
CONCLUSIONS
We discuss the implications of this study regarding denture designs, specifically the importance of using a radiopaque acrylic, using clasps when required even if there is a risk of aspiration, advising patients to return if a denture is loose or damaged, and finally that all patients who wear a denture are at risk of aspiration and swallowing events, and associated morbidity and mortality.
PubMed: 27489607
DOI: 10.5037/jomr.2016.7203