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Title Internal Reinforcement of Implant-Supported Overdentures Significantly Improves Fracture Resistance
Clinical Question For implant overdentures, does internal reinforcement of the resin denture base compared to overdentures without reinforcement decrease the incidence of denture base fracture?
Clinical Bottom Line Internal reinforcement of implant overdentures results in a decreased incidence of denture base fracture compared to implant overdenture bases with no internal reinforcement. Both metal and nonmetal materials can be used to advantage.
Best Evidence (you may view more info by clicking on the PubMed ID link)
PubMed ID Author / Year Patient Group Study type
(level of evidence)
#1) 26124604Murthy/201510 samples each of 3 maxillary denture bases with different methods of reinforcement + 1 control withoutLaboratory study
Key results4 groups (n=10) of maxillary denture bases were fabricated to include different reinforcement materials (no reinforcement, stainless steel mesh, woven glass fibers, and woven polyethylene fibers). Dentures were subjected to falling weight stress until crack initiation and complete fracture were occurred. Reinforcement of the dentures significantly improved fracture strength, with highest impact strength in the group with polyethylene fibers, followed by glass fibers, then metal mesh (P < 0.001).
#2) 26478980Takahashi/20155 experimental dentures: 4 reinforced with cast frames of different designs + 1 control with no frameLaboratory study
Key resultsFive experimental models of reinforcement were bench tested for strain from occlusal loads: no reinforcement (control) and cast cobalt-chrome reinforcement (4 mm wide x 0.5 mm thick) of four designs (reinforcement over the residual ridge and over the top of copings; over the coping tops with additional first molar to first molar reinforcement; reinforcement over the residual ridge and the sides of the copings; and around the coping sides with additional first molar to first molar reinforcement). Dentures with reinforcement experienced significantly less strain over implant sites than dentures with no reinforcement (P < .05). Reinforcement with cast chrome over the top of copings had significantly lower strain than reinforcement around the side of the copings (P<.05).
#3) 22024179Rached/20118 samples each of 6 implant overdentures with different methods of reinforcement + 1 control withoutLaboratory study
Key resultsTest specimens were fabricated out of acrylic resin, incorporating two metal O-ring capsules 20 mm apart. A space of 1 mm or 2.5 mm was created over the attachments for reinforcement of the acrylic denture base. Test materials (no reinforcement, stainless steel braids, stainless steel mesh, unidirectional E-glass, E-glass mesh, polyethylene braids, and polyaramid fiber) were incorporated and tested under fatigue and static loads. The space available for reinforcement did not significantly affect the strength or static load capacity of any group. Reinforcement material was the source of variance for fracture under fatigue and static load (P < .006 and P < .001 for 2.5 mm and 1 mm, respectively). For static loading, mean flexural strength showed no significant differences in reinforcement vs. control at 1 mm (P = 1.0), while unidirectional E-glass, polyethylene braids, and polyaramid fibers at 2.5 mm exhibited significantly higher flexural strength than control and E-mesh groups (P = .016, P = .003, P = .003, respectively).
Evidence Search ("denture, overlay"[MeSH Terms] OR ("denture"[All Fields] AND "overlay"[All Fields]) OR "overlay denture"[All Fields] OR "overdenture"[All Fields]) AND ("Stress"[Journal] OR "stress"[All Fields]) AND ("reinforcement (psychology)"[MeSH Terms] OR ("reinforcement"[All Fields] AND "(psychology)"[All Fields]) OR "reinforcement (psychology)"[All Fields] OR "reinforcement"[All Fields])
Comments on
The Evidence
Validity: The level of evidence regarding reinforcement of implant overdenture bases is remarkably low. Clinical studies are primarily case reports. Some of the cited studies are focused on conventional denture bases, but the results can presumably be extrapolated to implant overdentures. It is difficult to draw reliable conclusions from the available evidence on which material may provide superior fracture resistance, but it is clear overall that reinforcement provided superior resistance to stress. Perspective: In vivo studies with larger sample sizes are needed to assess the relative efficacy of reinforcing materials.
Applicability Implant supported overdentures have become a standard of care in the edentulous mandible, but they are not without complications. The top of the implant coping creates a fulcrum, acting as a site of stress concentration. Therefore, fatigue of acrylic resin over this site can lead to fracture of the denture base. Reinforcement over the residual ridge and implant copings is highly recommended in fabrication of implant-supported dentures for this reason. The benefits of reinforcement must be weighed against the risk of fracture without reinforcement and the added cost. Several bench studies have shown a variety of materials to be effective in reinforcing acrylic to reduce stress concentration over implant copings.
Specialty/Discipline (General Dentistry) (Prosthodontics)
Keywords Denture, denture base, overdenture, dental implant, resin fracture, reinforcement
ID# 3129
Date of submission: 11/26/2016spacer
E-mail pitz@uthscsa.edu
Author Anna Pitz, DDS
Co-author(s) e-mail
Faculty mentor/Co-author Stephan Haney, DDS
Faculty mentor/Co-author e-mail haneys2@uthscsa.edu
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