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Indian Journal of Dental Research :... Jan 2024Rehabilitation of partially edentulous arches with a cast partial denture is a commonly opted treatment modality where fixed prosthesis is not indicated. However, due to...
Rehabilitation of partially edentulous arches with a cast partial denture is a commonly opted treatment modality where fixed prosthesis is not indicated. However, due to the aesthetic compromise of the various metal components when placed in the esthetic zone, different modifications have been considered for its fabrication. This case report describes a novel way of restoring partially edentulous arches with increased masticatory efficiency and good emergence profile without compromising the patient's esthetic desires. The report describes an aesthetic alternative using thermoplastic denture base clasp like extension for anterior abutment teeth while restoring the missing teeth with a cast partial denture.
Topics: Humans; Dental Abutments; Denture Design; Denture Bases; Jaw, Edentulous, Partially; Esthetics, Dental; Dental Clasps; Female; Male
PubMed: 38934758
DOI: 10.4103/ijdr.ijdr_97_23 -
The Saudi Dental Journal Jun 2024This in vitro study aimed to evaluate the additive manufacturing (AM) of cobalt chromium Co-Cr and titanium Ti alloy clasps for clinical use. After scanning the Ni-Cr...
This in vitro study aimed to evaluate the additive manufacturing (AM) of cobalt chromium Co-Cr and titanium Ti alloy clasps for clinical use. After scanning the Ni-Cr die of the first molar, Akers' clasps were designed using computer-aided design/ computer-aided manufacturing (CAD/CAM). The clasps were manufactured from Co-Cr-W dental alloy and Ti-6Al-4V alloy powder using AM machines. Then, they were divided into two groups. The initial retentive force of the clasps was measured using a universal testing machine. Cyclic loading of the clasps was carried out by a specially designed insertion-removal testing apparatus in wet condition up to 5000 cycles. Retentive force was measured at 1000, 2000, 3000, 4000, and 5000 cycles. Moreover, the intaglio surface of each clasp was scanned using the scanner; and superimposition between the pre- and post-cycling clasp files was performed to evaluate deformation after cyclic loading. The fitting surfaces of retentive clasp tips were examined with a scanning electron microscope (SEM). Finally, it has been found that the initial retentive force for the Co-Cr group was 10.81 ± 0.37 N, and for the Ti group was 5.41 ± 0.18 N. Additionally, during the testing periods, both Co-Cr and Ti clasps continued to lose retentive force within the cycles of placement and removal. This effect was more prominent in the Co-Cr than in the Ti clasps. The distances between pre- and post-cycling in the retentive arm were -0.290 ± 0.11 mm and -0.004 ± 0.01 mm in Co-Cr and Ti alloys, respectively, and in the reciprocal arm were -0.072 ± 0.04 mm and -0.032 ± 0.04 mm in Co-Cr and Ti alloys, respectively. The retentive force required to remove the Ti clasps was found to be significantly lower than those required to dislodge the Co-Cr clasps. Co-Cr and Ti clasps lost significant amounts of retentive force from the initial use to the 3.5-year periods of simulated clinical use.
PubMed: 38883903
DOI: 10.1016/j.sdentj.2024.04.001 -
Clinical Oral Investigations Apr 2024The primary objective of the present retrospective clinical study was to determine the survival time of obturators while analyzing possible influencing factors.
OBJECTIVES
The primary objective of the present retrospective clinical study was to determine the survival time of obturators while analyzing possible influencing factors.
MATERIALS AND METHODS
This retrospective clinical cohort study analyzed the influence of various clinical factors on the survival probability of obturators and their follow-up outcomes using Kaplan‒Meier analysis.
RESULTS
A total of 76 patients with 115 obturators were included in the study (47 men and 29 women, mean age 58.1 ± 18.1 years). The mean observation time was 3.0 ± 4.5 years (maximum 26.3 years). A total of 40.9% (47) of all obturators observed had to be replaced. The survival rate after 5 years was 79.5% for telescopic-crown-retained tooth-supported obturators, 86.9% for telescopic-crown-retained implant-supported obturators, 58.8% for removable full denture obturators, 22.1% for clasp-retained obturators and 0.0% for splints. The type of attachment, attendance at a regular follow-up and defect cause significantly influenced the survival of the obturators (p < .05).
CONCLUSIONS
The findings obtained in this study support the recommendation of using implant-supported obturators. Telescopic-crown attachments, either tooth- or implant-supported, seem to be favorable in terms of survival time. Attendance at a strict follow-up program seems to have a major influence on the longevity of the obturators.
CLINICAL RELEVANCE
The use of implant-supported obturators to cover permanent oral and maxillofacial defects is highly recommended. Additionally, the use of telescopic-crown attachments seems to be favorable in terms of survival time. Clasp-retained obturators and surgical splints should be used primarily for temporary restorations due to their shorter survival times.
Topics: Humans; Middle Aged; Retrospective Studies; Male; Female; Dental Restoration Failure; Dental Prosthesis, Implant-Supported; Aged
PubMed: 38684542
DOI: 10.1007/s00784-024-05681-8 -
Medicine Apr 2024This paper demonstrates a digital manufacturing technique of a removable orthodontic appliance from an intraoral scan. An intraoral scan was made for the maxillary and...
This paper demonstrates a digital manufacturing technique of a removable orthodontic appliance from an intraoral scan. An intraoral scan was made for the maxillary and mandibular arches. 3Shape Orthodontics Appliance Designer produced the virtual Hawley retainer, consisting of alloy components (Adam Clasps and Fitted Labial bow) and a base plate. The base plate design was modified to adapt to inserting the alloy components, which were combined using cold-cured acrylic. The finished Hawley retainer was assessed intraorally. The described technique emphasizes the design specifications of digitally designed and manufactured removable orthodontic appliances. A combination of additive and subtractive techniques was successfully employed to manufacture the alloy components and base plate. This novel method provides an alternative approach to manufacturing removable appliances with computer-aided design (CAD)/computer-aided manufacturing (CAM) technologies. The described process offers a precursor to digital manufacturing of other developed designs of dental appliances.
Topics: Humans; Printing, Three-Dimensional; Computer-Aided Design; Orthodontic Appliance Design; Polymers; Benzophenones; Polyethylene Terephthalates; Ketones; Alloys; Orthodontic Appliances, Removable
PubMed: 38669369
DOI: 10.1097/MD.0000000000038004 -
General Dentistry 2024Squamous cell carcinoma (SCC) is the type of cancer that most frequently affects the oral cavity, mainly in men older than 50 years of age. Treatment for oral SCC often...
Squamous cell carcinoma (SCC) is the type of cancer that most frequently affects the oral cavity, mainly in men older than 50 years of age. Treatment for oral SCC often involves surgical excision of the affected margins, resulting in mutilation that affects the patient's quality of life. The objective of this case report is to describe the prosthetic treatment of a 56-year-old man who underwent total glossectomy, resulting in speech and swallowing difficulties. The proposed treatment was a tongue prosthesis retained by orthodontic clasps on the mandibular first molars. After maxillary and mandibular complete-arch impressions were performed and casts were prepared for prosthetic planning, an acrylic resin plate and 3 tongue prototypes were fabricated. Esthetic and functional tests were carried out, and 2 tongue models (1 for speech and 1 for eating) were selected for acrylization, finishing, and polishing. After placement of the prostheses, the patient was referred for follow-up with a speech therapist to improve his adaptation with the prostheses. The patient was satisfied with the prostheses and able to perform the functions of chewing, swallowing, and speech production, which helped in his social reintegration and improved his quality of life.
Topics: Male; Humans; Middle Aged; Glossectomy; Quality of Life; Dental Implants; Tongue; Mouth Neoplasms; Tongue Neoplasms
PubMed: 38640007
DOI: No ID Found -
Journal of the Mechanical Behavior of... Jun 2024Polyetheretherketone (PEEK) is considered as an alternative to metal material for removable partial denture (RPD). However, the retentive force is not strong as a metal...
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.
Topics: Denture Retention; Polyethylene Glycols; Polymers; Ketones; Chromium Alloys; Denture, Partial, Removable; Dental Stress Analysis; Dental Clasps; Benzophenones
PubMed: 38598917
DOI: 10.1016/j.jmbbm.2024.106539 -
The European Journal of Prosthodontics... Apr 2024The purpose of this study was to investigate the influence of undercut depths on abutment teeth regarding the retentive force of clasps fabricated through selective...
INTRODUCTION
The purpose of this study was to investigate the influence of undercut depths on abutment teeth regarding the retentive force of clasps fabricated through selective laser melting (SLM), and to compare them with conventional cast clasps.
METHODS
Akers clasps made of cobalt chromium alloy were fabricated using the SLM method (SLM), and the retentive forces were compared with clasps made with the conventional cast method (Cast). Three undercut amounts (0.25 mm, 0.15 mm, and 0 mm) were applied on the abutment tooth. The specimens were subjected to 10,000 repetitive insertion/removal cycles.
RESULTS
SLM-0.15 showed slightly lower initial retentive force than the Cast specimens, it remained within an acceptable range. During insertion/removal test, the SLM-0.15 specimen showed a significant difference between the initial retentive force and the retentive force after 5,000 cycles, indicating that SLM-0.15 was the least likely to change in retentive force within the parameters established in this study. The inner clasp surface on the SLM groups had higher surface roughness before testing compared to the Cast specimen.
CONCLUSIONS
Akers clasps fabricated by SLM demonstrated optimal initial retentive forces with smaller undercuts than conventional Cast clasps, and the retentive forces changed less with repetitive insertion/removal.
PubMed: 38591550
DOI: 10.1922/EJPRD_2648Tomono09 -
Journal of Prosthodontic Research Feb 2024The processes and methods of treating and polishing additive-manufactured (AMed) cobalt-chromium (Co-Cr) alloy clasps were assessed in vitro to determine their...
PURPOSE
The processes and methods of treating and polishing additive-manufactured (AMed) cobalt-chromium (Co-Cr) alloy clasps were assessed in vitro to determine their suitability for constant clinical use and the reduction of dental technician work.
METHODS
AMed Aker clasps were fabricated by selective laser sintering of approximately 50 μm Co-Cr alloy powders. After the nodules and fins on the inner surface of the AMed clasps were removed and morphological correction was performed, a dental technician manually polished the clasps as a control. Four surface treatments, barrel finishing, shot peening, and wet and dry electropolishing, were performed to obtain smooth surfaces. In addition, hybrid manufacturing, which integrates repeated laser sintering and high-speed milling for one-process molding, was added to this study. After observing the treated surfaces using SEM and Hybrid Laser Microscope (HLM) the surface roughness, fitness accuracy, and retentive forces of the treated AMed clasps were measured, and their polishing efficiencies were compared.
RESULTS
Similar to manual polishing, dry electropolishing yielded the smoothest surfaces in all treatments. The fitness accuracy of all clasp regions and treatment methods ranged from 80 to 140 μm, without significant differences among the treatment methods. All treated clasps showed acceptable retentive forces for clinical use, and hybrid manufacturing and wet electropolishing showed significantly higher forces.
CONCLUSIONS
AMed Co-Cr clasps with all surface treatments could be clinically used if additional slight manual polishing was performed; however, each processing condition should be carefully selected.
PubMed: 38417870
DOI: 10.2186/jpr.JPR_D_23_00258 -
Cureus Dec 2023Maxillectomy defects can lead to oroantral communication, causing difficulties with chewing, swallowing, speech, and facial appearance. Prosthodontists play a crucial...
Maxillectomy defects can lead to oroantral communication, causing difficulties with chewing, swallowing, speech, and facial appearance. Prosthodontists play a crucial role in rehabilitating such defects using obturators. This case report presents the fabrication of a definitive obturator with a cast metal framework for a patient who had an acquired maxillary defect and previously experienced issues with an ill-fitting obturator. In this clinical report, the patient's canine teeth on both sides and the premolars and molars on the left side were used for rest placement. Retention was achieved by utilizing the remaining teeth, employing two embrasure Aker clasps on the left molars and premolars and a C-wrought wire clasp on the right canine. A complete palate was designed as the major connector to ensure optimal load distribution to the surrounding tissues. Additionally, an indirect retainer was planned for the right canine. This definitive prosthesis rehabilitated the patient, improving masticatory efficiency, enhancing speech clarity, and improving quality of life.
PubMed: 38222126
DOI: 10.7759/cureus.50578 -
Journal of Prosthodontic Research Jan 2024This study aimed to investigate the retentive force and deformation of double Akers' polyetherketoneketone (PEKK) clasps on removable partial dentures (RPDs) with...
PURPOSE
This study aimed to investigate the retentive force and deformation of double Akers' polyetherketoneketone (PEKK) clasps on removable partial dentures (RPDs) with varying designs and undercut depths.
METHODS
Thirty double Akers' PEKK clasps with two different widths and heights (Groups I and II) were fabricated using computer-aided design and computer-aided manufacturing (CAD/CAM). Each design was further subdivided (n = 5) into three undercut depths (0.25, 0.50, and 0.75 mm). The retentive force of the clasps was measured after 10 years of clinical use (15,000 insertion/removal cycles), and the deformation of the clasp tips was analyzed before and after cycling.
RESULTS
Clasps with 0.50-mm and 0.75-mm undercut depths exhibited greater initial retentive forces (3.15-3.51 N) compared to those in the 0.25-mm undercut group (2.40-2.80 N). Group I maintained consistent retentive forces over the cycles (P = 0.345), whereas Group II showed declining forces after the initial use (P < 0.003). In both groups, the 0.50-mm undercut exhibited a greater retentive force than the 0.25-mm (P < 0.001 and P < 0.004, respectively), with no significant differences between the 0.50-mm and 0.75-mm undercut depths. Despite a lower initial retentive force, the 0.25-mm undercut showed less deformation and clasp tip wear.
CONCLUSIONS
The PEKK clasps did not exhibit significantly reduced retentive forces or permanent deformations after 15,000 fatigue cycles. These results suggest that the PEKK polymer displays superior mechanical properties as an esthetic clasp material, and clasps with 0.50-mm and 0.75-mm undercut depths are recommended for long-term clinical use.
PubMed: 38220161
DOI: 10.2186/jpr.JPR_D_23_00080