CATEGORY AUSTRALASIAN DENTIST 77 However, Canabarro et al. (2000), found no correlation between age and MMF19, thus further studies are required that would include a bigger variety of ages to draw more conclusive results21. The medial mandibular flexure can affect the oral rehabilitation as Sivaraman et al., demonstrated in their research that during oral rehabilitation not a lot of attention is attributed to the deformation from MMF during protrusion and opening of the jaw8. It was not believed that mandibular flexure could cause any major implications in the longevity of treatments6,8. However, MMF has been proven to affect many aspects of the stomatognathic system and also affect treatments. It could influence periodontal treatment, restorative treatments and also fixed, removable or implant supported prosthesis4,13,14. The importance of taking into account the flexure of the mandible was highlighted, not only for a favorable outcome of dental treatments but also for the maintenance of health of periodontal, periimplant and gingival tissue4,27. The fabrication of bridges and crowns for posterior teeth is usually based on impressions that are taken when the patient opens the mouth and thus the mandible is subjected to deformation by MMF9,28. As a result, the prosthesis might not adapt on the abutments or there might be extra contacts during occlusion8. MMF has also been found to interfere with certain stages of implant based oral rehabilitation. It can interfere with the osseointegration of implants as MMF causes stress on the lateral surface of implants which could lead to greater loss of the bone that surrounds the implants30-32. Consequently, mandibular flexure could lead to loss of anchorage of implants, fracture of material, screw loosening and even discomfort and/or pain of patients6,8. The presence of the periodontal ligament in natural teeth reduces the amount of deformation caused by MMF. Osseointegrated implants on the other hand don’t have periodontal ligament and thus don’t absorb any displacement, which results in a greater deformation of the mandible33. Full arch restorations with implants that have distal cantilevers are more rigid than the mandible and don’t experience anequal amount of deformation as the mandible from MMF. This generates stress on the bone that leads to bone loss1,6. Sectioning the framework in the symphysis into two frameworks can decrease the stress on the bone and permit a more natural deformation of the mandible by MMF1,8,9,33-35. However, this could negatively influence the esthetics of the final restoration and the hygiene of the patients as it could lead to food impaction at the connection area of the two frameworks6,33. According to the revised study, the list of problems is: u Increased stress in dental implantrelated prosthesis and abutments u Poor fit of fixed or removable prostheses u Impression distortion u Pain during function u Fracture of screws of implants or porcelain crowns u Loosening of cemented prostheses u Screw loosening u Resorption around implant Clinical implications According to the literature, it is advisable to split the framework at least along the midline if we must rehabilitate a mandibular edentulous patient. Another option would be to split the framework into three parts: 6-4, 3-3, 4-6. By cutting in the midline or in three parts, we reduce the risk of having the problems listed because we do not get in the way of the patient’s natural mandibular flexion. u For a list of references email: gapmagazines@gmail.com Fig. 1: Different images showing bone resorption around distal (bilaterally) implants when rehabilitated with a rigid splinted framework in the edentulous mandibular patient. We can see that only distal implants have bone resorption. LINICAL 1800 806 450 www.amalgadent.com.au THE BEST JUST GOT BETTER SEE BACK COVER FOR SPECIAL OFFER! Now for ALL Classes I – VI BulkEZPlus Footer #96.indd 3 25/10/2022 9:04:54 AM
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