Effect of different fabrication workflows on the passive fit of screw-retained bar splinting two interforaminal implants: a parallel blinded randomised clinical trial.

BACKGROUND: To clinically compare the effect of the conventional and the digital workflows on the passive fit of a screw retained bar splinting two inter-foraminal implants. METHODS: The current study was designed to be a parallel triple blinded randomised clinical trial. Thirty six completely edentulous patients were selected and simply randomized into two groups; conventional group (CG) and digital group (DG). The participants, investigator and outcome assessor were blinded. In the group (CG), the bar was constructed following a conventional workflow in which an open top splinted impression and a lost wax casting technology were used. However, in group (DG), a digital workflow including a digital impression and a digital bar milling technology was adopted. Passive fit of each bar was then evaluated clinically by applying the screw resistance test using the "flag" technique in the passive and non passive situations. The screw resistance test parameter was also calculated. Unpaired t-test was used for intergroup comparison. P-value < 0.05 was the statistical significance level. The study protocol was reviewed by the Research Ethics Committee in the author's university (Rec IM051811). Registration of the clinical trial was made on clinical trials.gov ID NCT05770011. An informed consent was obtained from all participants. RESULTS: Non statistically significant difference was denoted between both groups in all situations. In the passive situation, the mean ± standard deviation values were 1789.8° ± 20.7 and1786.1° ± 30.7 for the groups (CG) and (DG) respectively. In the non passive situation, they were 1572.8° ± 54.2 and 1609.2° ± 96.9. Regarding the screw resistance test parameter, they were 217° ± 55.3 and 176° ± 98.8. CONCLUSION: Conventional and digital fabrication workflows had clinically comparable effect on the passive fit of screw retained bar attachments supported by two dental implants.

Clinical evaluation of the effect of two resilient attachments retaining mandibular over-denture supported by implant and natural tooth on the supporting structures

Aim: This study aimed to assess the effect of two resilient attachments used for retention of mandibular over-denture supported by an implant and a natural tooth on the supporting structures throughout a one-year follow-up period. Materials and methods: Fourteen patients with maxillary completely edentulous arches and only one standing natural mandibular canine were selected. Each patient received a dental implant with 10.5 mm length and 3.8 mm diameter at the canine region of the contralateral side of the mandible. The patients were divided into two groups according to the type of attachment used (n=7); BC group included patients who received mandibular over-dentures retained by bar clip attachment supported by an implant on one side and a natural tooth on the other side. BS group involved patients who received a mandibular implant splinted to the natural canine by bar joint attachment utilizing soft liner material. The patients of both groups were rehabilitated with conventional maxillary complete dentures. Clinical and radiographic assessment were performed immediately after over-denture delivery, six and twelve months from denture insertion. Clinical evaluation involved gingival index. Radiographic evaluation included measuring mesial, distal, buccal and lingual bone height differences. Results: BC group recorded significantly higher bone loss compared to BS group around both dental implants and natural teeth. Conclusion: Considering the limitations of this study, it could be concluded that soft liner retained over-dentures are more effective in decreasing bone resorption around the implants and natural teeth compared to clip retained over-dentures.

Electromyographic Connectivity of Masseter Muscle with Different Retentive Attachments for Implant Overdentures in Patients with Atrophied Mandibular Ridges: A Crossover Study.

PURPOSE: The aim of this crossover study was to evaluate electromyographic (EMG) connectivity of masseter muscle with different attachments used to retain implant overdentures in patients with atrophied mandibular ridges. MATERIALS AND METHODS: Twenty-four edentulous participants with atrophic mandibular ridges received conventional dentures (control). Three months after the adaptation period, two implants were placed in the canine areas of the mandible. After osseointegration, each participant was successively given the following prostheses in a crossover manner: (1) ball-retained overdentures, (2) bar-retained overdentures, and (3) -retained overdentures. The EMG parameters (amplitude, chewing area, chewing rate, duration of chewing cycle, duration of chewing burst, and chewing time) were measured 3 months after wearing the following prostheses: conventional dentures, ball overdentures, bar overdentures, and Locator overdentures. Measurements were made during chewing of hard (carrot) and soft (cake) foods. RESULTS: The highest EMG activity/amplitude, chewing area, duration of chewing cycle, and duration of chewing burst were noted with ball overdentures, followed by bar overdentures and Locator overdentures, and the lowest values were observed with conventional dentures. The highest chewing rate and masticatory time were noted with conventional dentures and the lowest values were observed with ball overdentures. With the exception of chewing area, no significant differences in all tested parameters between bar overdentures and Locator overdentures were observed. Except for duration of chewing cycle, all tested parameters were significantly higher during chewing of hard food than soft food. CONCLUSION: Within the limitations of this study, two-implant overdentures recorded higher muscle functions compared to conventional dentures regardless of the type of attachment used. For such overdentures, ball attachment may be recommended over bar and Locator attachments, as it was associated with improved muscle activity and function.