Oral health-related quality of life in patients with non-metal clasp dentures: a randomised cross-over trial

Oral health-related quality of life of conventional removable partial dentures, unilateral nonmetal clasp dentures, and shortened dental arch with 2- or 3-tooth unilateral distal extension tooth loss in the mandible: A randomized, crossover, clinical trial

STATEMENT OF PROBLEM

Conventional removable partial dentures with metal clasps are still a common option for patients with distal-extension tooth loss. However, unilateral nonmetal clasp dentures fabricated by using a thermoplastic denture base resin are increasingly being used. Furthermore, the shortened dental arch concept remains controversial, in spite of being advocated for many years. Nevertheless, these treatment options remain controversial, particularly in patients with the loss of a few distal teeth unilaterally.

PURPOSE

The purpose of this randomized, crossover, clinical trial was to investigate the oral health-related quality of life of participants who requested a new dental prosthesis (unilateral nonmetal clasp dentures or conventional removable partial dentures) at a private practice.

MATERIAL AND METHODS

A 3-period, randomized, crossover design was used in a within-subject, controlled, clinical trial. Twenty-four participants (mean age 59.0 years [7 men: 62.6 {45-85} years; 17 women: 57.5 {24-75} years]) were enrolled. All experimental procedures were approved by the Ethics Committee of Nagasaki University Hospital (#15022313) and registered in the International Standard Randomized Controlled Trial Number registry (ISRCTN49105064). All participants were fully dentate in the maxilla and had unilateral distal-extension loss of 2 or 3 teeth in the mandible. Participants were allocated to 1 of 6 groups and treated with prescribed options in accordance with their allocated sequences and used a dental prosthesis or nothing for 2-week periods. At the end of each intervention, the participants were asked to answer the Oral Health Impact Profile questionnaire. Differences in Oral Health Impact Profile scores among groups were estimated with a mixed-effects model (α=.05).

RESULTS

Total Oral Health Impact Profile scores were higher for unilateral nonmetal clasp dentures (P=.002) and shortened dental arch (P=.049) than for conventional removable partial dentures, with medium and small effects. The unilateral nonmetal clasp dentures had a similar effect compared with shortened dental arch (P>.05). unilateral nonmetal clasp dentures (P=.011) and shortened dental arch (P=.005) demonstrated medium effects in the oral function dimension compared with conventional removable partial dentures. Unilateral nonmetal clasp dentures exhibited large and medium effects in the orofacial appearance dimension compared with conventional removable partial dentures (P=.001) and shortened dental arch (P=.006). In the orofacial pain dimension, shortened dental arch showed effects similar to those of conventional removable partial dentures and unilateral nonmetal clasp dentures (P>.05), and no significant differences were observed in the psychosocial impact dimension (P>.05), but the unilateral nonmetal clasp denture score was lower than the conventional removable partial denture score, with a small effect. Men had significantly lower total Oral Health Impact Profile scores for shortened dental arch than women (P=.033).

CONCLUSIONS

Unilateral nonmetal clasp dentures and shortened dental arch were better than conventional removable partial dentures for the oral health-related quality of life of individuals with unilateral distal-extension tooth loss in the mandible, and sex had a significant effect on removable prosthetic planning.

Effectiveness of a 3D simulation tool to teach the designing of metal removable partial dentures: A mixed-method study

INTRODUCTION

Acquiring insights into the framework design of metal-based removable partial dentures (mRPD) is a current challenge in dental education. The aim of the present study was to explore the effectiveness of a novel 3D simulation tool to teach designing mRPD by investigating the learning gain and the acceptance and motivation towards the tool of dental students.

MATERIALS AND METHODS

A 3D tool based on 74 clinical scenarios was developed for teaching the design of mRPD. Fifty-three third year dental students were randomly divided into two groups, with the experimental group (n = 26) having access to the tool during 1 week while the control group (n = 27) had no access. Quantitative analysis was based on a pre- and post-test in order to evaluate the learning gain, technology acceptance and motivation towards using the tool. Moreover, qualitative data was collected by means of an interview and focus group to get additional insights into the quantitative results.

RESULTS

Although the results showed a higher learning gain for students in the experimental condition, the study did not find a significant difference between both conditions based on quantitative results. However, during the focus groups, all students of the experimental group revealed that the 3D tool improved their understanding of mRPD biomechanics. Moreover, survey results revealed that students positively evaluated the perceived usefulness and ease of use of the tool and indicated to have the intention to use the tool in the future. Suggestions were made for a redesign (e.g. creating scenarios themselves) and further implementation of the tool (e.g. analysing the scenarios in pairs or small groups).

CONCLUSION

First results of the evaluation of the new 3D tool for teaching the design framework of mRPD are promising. Further research based on the design-based research methodology is needed to investigate the effects of the redesign on motivation and learning gain.

The effect of clinical interventions on the oral health-related quality of life in older adults

This paper reviews the literature to assess the effectiveness of oral health interventions in influencing oral health-related quality of life (OHRQoL) in older adults. Clinical studies published in 2010 onwards reporting oral health interventions in older adults and subsequent changes in OHRQoL were systematically searched in Medline, Web of Science and EMBASE databases. Reporting followed Preferred Reporting Items for Systematic Review and Meta-Analysis criteria. Eligibility evaluation and data abstraction from eligible studies were guided by predefined PICO questions and bias assessment by the Quality in Prognosis Studies tool. The search retrieved 144 articles. Of the 20 articles that met the eligibility criteria, 45% (9) reported a statistically significant improvement in OHRQoL. The majority of studies were conducted in adults with complete edentulism (70%) and mainly focused on implant provision to support a removable prosthesis (30%). The search indicates the limited scope of current literature on geriatric dental interventions, focusing mainly on denture realignments, denture fabrication and implant placement. Although the majority of the oral health interventions focused on edentulism and removable prostheses, there are many areas of oral health interventions and their potential impact on OHRQoL in this demographic group that have yet to be explored.

Effect of retention hole designs in artificial teeth on failure resistance of the connection with thermoplastic resin

This study aimed to evaluate the effect of retention hole designs in artificial teeth on failure resistance of the connection with a thermoplastic denture base resin. Artificial teeth with the following retention hole designs were attached to polyester and polyamide resins: no hole, vertical hole, horizontal hole, and vertical and horizontal holes. An artificial tooth with no hole attached to polymethyl methacrylate was prepared as the control. The load was applied until connection failure occurred between the artificial tooth and resin, and failure resistance was detected. Although the control showed the highest resistance, the artificial tooth with vertical and horizontal holes showed higher resistance than those with other retention hole designs in both thermoplastic resins. Providing vertical and horizontal retention holes in artificial teeth may be effective in improving failure resistance of the connection with thermoplastic resins.

Stress distribution and patient satisfaction in flexible and cast metal removable partial dentures: Finite element analysis and randomized pilot study

Purpose

To compare stress distribution in polyacetyl based flexible RPD (FRPD) with cast metal RPD (CRPD) by using three-dimensional finite element analysis (FEA) and patient satisfaction by using OHIP-14 questionnaire in participants with Kennedy's class I partially edentulous mandibular arch rehabilitated with CRPD and FRPD.

Material and methods

For FEA, 3D models of Kennedy's class I partially edentulous mandibular arch, CRPD in chrome-cobolt alloy, and polyacetyl based FRPD were geometrically modelled and subjected to a vertical load of 100 ​N bilaterally. The in vivo comparison of satisfaction was assessed by enrolling 22 participants with Kennedy's class I partially edentulous mandibular arch. After randomization, 11 participants were rehabilitated by CRPD (group C), and 11 participants by polyacetyl based FRPD (group F). OHIP-14 questionnaire in Hindi language was filled at 1 week and 1 year after denture insertion.

Results

Von Mises stress distribution in CRPD was maximum in mesial rest seat of the primary abutment (100 ​MPa) and minimum for edentulous ridge (7 ​MPa on bone and 6 ​MPa on mucosa). Von Mises stress distribution for polyaccetyl based FRPD was maximum in ridge (25 ​MPa) and minimum in periodontal ligament of the second premolar (3 ​MPa). Patient satisfaction in group F was significantly more than in group C at end of 1 year (P ​= ​.0158).

Conclusion

FRPD is useful in periodontally compromised abutment teeth and CRPD in resorbed ridge conditions. Patient satisfaction is more with polyacetyl based flexible RPD when compared with cast metal RPD at the end of 1 year.

Short-term effect of thermoplastic resin removable partial dentures on periodontal health: a randomized cross-over trial

PURPOSE

This study aimed to compare the short-term effects of thermoplastic resin removable partial dentures (TR-RPDs), referred to as non-metal clasp dentures, with those of metal-clasp-retained RPDs (MC-RPDs) on the periodontal health of abutment teeth.

METHODS

A randomized cross-over trial was conducted in 28 partially dentate patients. Participants were randomized into two groups and received MC-RPDs followed by TR-RPDs, or vice versa, for 3 months. Periodontal clinical parameters, such as the plaque index, gingival index, probing pocket depth, tooth mobility, and microbiological status of the abutment teeth, were evaluated at the delivery and 3 months after using each RPD.

RESULTS

Of the 28 patients enrolled, 24 (mean age, 67.3 years) completed the trial, and 55 abutment teeth were evaluated. The periodontal condition of the abutment teeth did not deteriorate after 3 months of using both types of RPDs. There was no statistically significant difference in the plaque index, gingival index, probing pocket depth, tooth mobility, and the red complex bacteria between TR- and MC-RPDs (p >0.05). The Periotest value for TR-RPDs was significantly lower than that for MC-RPDs (p <0.05). However, this difference was not clinically significant.

CONCLUSIONS

These results suggest that the influence of TR-RPDs on the periodontal health of abutment teeth was limited within 3 months of use.　Trial registration number: The study protocol was registered at UMIN-CTR (UMIN000007310).

Bond strength of artificial teeth to thermoplastic denture base resin for injection molding

This research was conducted to investigate the bond strength between artificial teeth and a thermoplastic denture base resin for injection molding with different surface preparations for use in flexible resin removable partial dentures. Composite resin denture teeth and acrylic denture resin teeth were bonded to three types of thermoplastic denture base resins for injection molding (polyamide, polyester, and polycarbonate) and a conventional heat-polymerized polymethyl methacrylate (PMMA) resin (control). The ridge lap surfaces of the artificial teeth were classified into four groups based on the type of ridge lap surface treatment applied (n=10): no treatment, ethyl acetate, small T-shaped tunnel, and large T-shaped tunnel. The specimens were tested for bond strength. The results showed that the ethyl acetate treatment was ineffective for enhancing the bond strength (p>0.05) between the artificial teeth and thermoplastic denture base resin for injection molding, whereas the T-shaped tunnel was quite effective in this regard (p<0.05).

Cost-effectiveness analysis of prosthetic treatment with thermoplastic resin removable partial dentures

PURPOSE

The aim of this study was to compare the cost-effectiveness of thermoplastic resin removable partial dentures (TR-RPDs) with metal clasp-retained removable partial dentures (MC-RPDs), from the patients' perspective.

METHODS

Patient-reported outcome measures (Oral health-related quality of life [OHRQoL], patient satisfaction, oral appearance) were assessed among 24 partially dentate subjects who completed a randomized crossover trial comparing TR-RPDs and MC-RPDs. The prosthetic treatment fee for patients was used as the direct cost. The cost of achieving a clinically minimum important difference (MID) in Oral Health Impact Profile (OHIP) summary score, and the incremental cost-effectiveness ratio (ICE R) for each outcome measure were determined.

RESULTS

OHRQoL, patient satisfaction, and oral appearance was rated higher with TR-RPDs compared to MC-RPDs. The median cost of achieving a MID in OHRQoL with TR-RPDs ($698) was 6.5 times higher than that with MC-RPDs ($107). The ICER was $67 for the OHIP summary score, $195 for the satisfaction score, and $1,169 for the oral appearance rating.

CONCLUSIONS

Although TR-RPDs provide better OHRQoL, patient satisfaction, and oral appearance than MC-RPDs, the cost-effectiveness of TR-RPDs was inferior to MC-RPDs from the patients' perspective.

Attachment-retained removable prostheses: Patient satisfaction and quality of life assessment

STATEMENT OF PROBLEM

Studies on the impact of incorporating attachments in removable prostheses on patient-based outcomes are scarce.

PURPOSE

The purpose of this clinical study was to investigate oral health-related quality of life (OHRQoL) and patient satisfaction in partially edentulous participants before and after rehabilitation with mandibular attachment-retained removable prostheses as compared with conventional removable prostheses.

MATERIAL AND METHODS

This crossover study included 74 participants (aged 36 to 57). Initially, 56 received conventional clasp-retained removable dental prostheses (RDPs), and 18 received conventional overdentures (ODs) based on their mandibular partially edentulous state. Two months later, of the 56 RDP participants, 24 had received extracoronal attachment-retained RDPs, 17 received telescope-retained RDPs, and 15 received bar-attachment retained RDPs. The 18 OD participants received ball attachment-retained ODs. Assessments included Oral Health Impact Profile-short version-14 for OHRQoL and a visual analog scale (VAS) for patient satisfaction. Assessments were done before treatment and 2 months after wearing each prosthesis with a 1-month washout period. Statistical analysis included the Friedman then the Wilcoxon signed rank test for Oral Health Impact Profile-short version-14 scores and repeated measures ANOVA then the Bonferroni or paired t test for VAS scores (α=.05).

RESULTS

There were no dropouts. Rehabilitation, irrespective of prosthesis type, significantly improved OHRQoL in all domains and significantly increased overall patient satisfaction (P<.05). When compared with the conventional prostheses, attachment-retained prostheses significantly improved functional limitation, psychological discomfort, and physical limitation domains in all groups (P<.05), as well as the physical pain domain in the OD group (P=.041). General satisfaction, stability, comfort, ability to speak, and ability to masticate significantly increased (P<.05) with attachment-retained prostheses. Conventional prostheses were significantly easier to clean (P<.05) in all groups, except for the telescope-attachment group.

CONCLUSIONS

Both conventional and attachment-retained prostheses significantly increased patient satisfaction and improved OHRQoL in all domains as compared with before treatment. However, incorporation of attachments further improved functional limitation, psychological discomfort, and physical limitation domains in all groups, as well as the physical pain domain in the OD group. Participants were more satisfied with their attachment-retained prostheses in most aspects.

Nonmetal clasp dentures: What is the evidence about their use?

The aim was to discuss the indications, contraindications, advantages, and disadvantages of Nonmetal clasp dentures (NMCDs), as well as the most relevant properties of its constituent materials. A search was conducted using the keywords: “nonmetal clasp dentures,” “thermoplastic resin,” “flexible resin removable partial denture,” “polyamide,” and “nylon” in databases PubMed/Medline, Lilacs, SciELO, and textbooks between 1955 and 2020. Theses and texts without reliable sources of publication were excluded. Once the analysis instruments were determined, the data were analyzed and discussed. NMCDs present high flexibility, easy adaptation to the abutments, color compatibility and biocompatibility with the oral mucosa, and absence of visible metal clasps. However, they need laboratory relining, grinding, and polishing, do not have criteria for its planning, become rougher and stained over time, and are able to traumatize supporting tissues. The association with metal components seems to be an alternative to increase the success of NMCDs by combining esthetics and biomechanical principles of conventional removable partial dentures. The lack of long-term clinical studies makes the professionals to rely solely on previous experiences or on the manufacturers' recommendations. It suggested that NMCDs must be indicated with caution when not used temporarily.

Patient satisfaction and preference with thermoplastic resin removable partial dentures: a randomised cross-over trial

PURPOSE

This randomised cross-over trial aimed to comparatively investigate patient preference and satisfaction with thermoplastic resin removable partial dentures (TR-RPDs) and conventional metal clasp-retained removable partial dentures (MC-RPDs).

METHODS

Twenty-eight partially dentate subjects were enrolled and randomised to receive MC-RPDs followed by TR-RPDs or vice versa (n=14, each group). The subjects were asked to score overall satisfaction and denture-related parameters 3 months after delivery of each denture. Additionally, they were asked to choose their preferred denture type at the end of the trial.

RESULTS

Of the 28 subjects, 24 (86%; mean age, 67.3 years) completed the trial. The overall satisfaction scores and ratings for oral appearance with TR-RPDs were significantly higher than those with MC-RPDs (P<0.05). Moreover, 75% (18/24) and 83% (20/24) of the subjects reported greater overall satisfaction and better oral appearance with TR-RPDs than with MC-RPDs (P<0.001, both). Scores for mucosal pain and food impaction were significantly better with TR-RPDs than with MC-RPDs (P<0.05). Relative to MC-RPDs, TR-RPDs provided slightly better oral comfort and speech, although the differences were not statistically significant (P>0.05). Scores for chewing ability, denture stability, and ease of denture cleaning were almost identical for both types of dentures.

CONCLUSIONS

These results suggest that TR-RPDs hold an advantage over MC-RPDs in terms of oral appearance and can offer greater satisfaction than MC-RPDs in partially dentate arches with at least an occluding pair in the posterior region.

CLINICAL TRIAL REGISTRATION

UMIN Clinical Trials Registry (UMIN000007310).

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

BACKGROUND

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Influence of block-out on retentive force of thermoplastic resin clasps: an in vitro experimental and finite element analysis

PURPOSE

The purpose of this study was to determine the effect of block-out preparation, used to eliminate the undercut area, on the retentive force and stress distribution of resin clasps.

METHODS

A total of 72 polyester and polyamide resin clasps were fabricated on a premolar abutment crown following six block-out preparations. A combination of two types of vertical block-outs and three types of horizontal block-outs (on the missing side) was used on the abutment tooth. Each clasp was subjected to an in vitro removal test using a universal testing machine. The retentive force and traces of the clasp on the abutment tooth were recorded and analyzed with one-way analysis of variance and post hoc comparisons (α=0.05). Non-linear finite element analysis was performed to assess the stress distributions of the resin clasps.

RESULTS

Resin clasps with a vertical block-out of 0.75mm undercut showed significantly higher retentive force than those with the 0.5mm undercut. Resin clasps with horizontal block-out showed significantly lower retentive force than those without horizontal block-out. There was no significant difference between the two thermoplastic resins. The maximum first principal stress of the resin clasp was concentrated under the shoulder of the clasp and strongly influenced by the width of horizontal block-out in the finite element analysis.

CONCLUSIONS

This in vitro experiment suggested that a horizontal block-out is necessary even for a 0.5-mm undercut. The design of the resin clasp should be considered from two aspects: retentive force and deformation risk.

Effects of polishing on surface roughness and hardness of glass-fiber-reinforced polypropylene

Removable partial dentures (RPDs) with resin-clasp retentive parts, which are known as non-metal-clasp dentures (NMCDs), have been used as alternatives for conventional RPDs with metal clasp, in case of aesthetic prosthodontic treatments. In this study, a profilometer and dynamic micro-indentation tests were used to investigate the effects of polishing on the surface properties such as surface roughness (Ra), dynamic hardness, and elastic modulus of high-rigidity glass-fiber-reinforced thermoplastics (GFRTPs) composed of E-glass fibers and polypropylene for NMCDs. The Ra values of the GFRTPs after polishing were significantly lower than those before polishing. The values were close to the Ra threshold level of 0.2, which corresponds to an acceptable surface smoothness for denture base materials. Polishing did not significantly change the dynamic hardnesses and elastic moduli of the GFRTPs. The fiber loading did not greatly affect the micromechanical properties of the GFRTPs because the glass-fiber reinforcement is embedded in the polypropylene matrix.

Glass fiber-reinforced thermoplastics for use in metal-free removable partial dentures: combined effects of fiber loading and pigmentation on color differences and flexural properties

PURPOSE

The purpose of this study was to investigate the combined effects of fiber loading and pigmentation on the color differences and flexural properties of glass fiber-reinforced thermoplastics (GFRTPs), for use in non-metal clasp dentures (NMCDs).

METHODS

The GFRTPs consisted mainly of E-glass fibers, a polypropylene matrix, and a coloring pigment: the GFRTPs with various fiber loadings (0, 10, and 20mass%) and pigmentations (0, 1, 2, and 4mass%) were fabricated by using an injection molding. The color differences of GFRTPs were measured based on the Commission Internationale de l'Eclairage (CIE) Lab color system, by comparing with a commercially available NMCD. The flexural properties of GFRTPs were evaluated by using a three-point bending test, according to International Standards Organization (ISO) specification number 20795-1.

RESULTS

The visible colors of GFRTPs with pigment contents of 2mass% were acceptable for gingival color, and the glass fibers harmonized well with the resins. The ΔE* values of the GFRTPs with pigment contents of 2mass% obtained by using the CIE Lab system were lowest at all fiber loadings. For GFRTPs with fiber contents of 10 and 20mass% at 2mass% pigment content, these GFRTPs surpassed the ISO 20795-1 specification regarding flexural strength (> 60MPa) and modulus (> 1.5GPa).

CONCLUSIONS

A combination of the results of color difference evaluation and mechanical examination indicates that the GFRTPs with fiber contents of 10 or 20mass%, and with pigment contents of 2mass% have acceptable esthetic appearance and sufficient rigidity for NMCDs.