Peri-implant bone defects: A 1-year follow-up comparative study of use of hyaluronic acid and xenografts.

OBJECTIVE: The aim of this study was to compare the efficacy of hyaluronic acid (HA) and xenografts on the repair of peri-implant dehiscence-type bone defects occur during implant placement. PATIENTS AND METHODS: Forty-two dehiscence Class I type defects located on the buccal surface of the implants were included in this study. Defects were divided into two main groups as small sized (height of <3 mm) and medium sized (height between 3 and 5 mm). Both of the main groups were further divided into two subgroups as HA plus xenograft plus collagen membrane (HAXC) or xenograft plus collagen membrane (XC) applied groups. After grafting, repair of defect site was evaluated with the help of the cross-sectional images on cone-beam computed tomography at 6th and 12th months. RESULTS: In both main groups, vertical bone height (VBH) was higher in defects repaired with HAXC (2.65 ± 1.12 mm) than in the XC (2.45 ± 1.10 mm) groups at the 6th month. However, the difference between two subgroups was not statistically significant (P > 0.05). Reduction in VBH was observed up to 6-12 months after prosthetic loading in all defect sites. This reduction was found statistically significant in medium-sized defects that grafted with XC (P < 0.05, paired t-test). However, in other subgroups, the difference between measurements at 6th and 12th months was not statistically significant (P > 0.05). CONCLUSIONS: According to the data obtained from this study, it can be concluded that HA did not have a significant positive effect on the repair of defects around dental implants.

A possible etiology of the internal derangement of the temporomandibular joint based on the MRI observations of the lateral pterygoid muscle.

The purpose of this study was to evaluate the relationship of the temporomandibular joint (TMJ) internal derangement and lateral pterygoid muscle (LPM) by magnetic resonance imaging (MRI). In this study, 115 subjects with TMJ internal derangement (total 230 TMJs) and 21 subjects without clinical symptoms (total 42 TMJs) were included. TMJ disc position and LPM were evaluated using MRI. LPM attachments were categorized into two different types: type 1, where fibers of the superior head of the LPM (SLPM) were attached to the disc and fibers of the inferior head of the LPM (ILPM) were attached to condyle, and type 2, where fibers of the SLPM were attached to the disc and condyle, and fibers of the ILPM were attached to condyle. The presence of muscle atrophy and degeneration were also evaluated. LPM attachments were observed in two different parts. Disc displacements were common in the muscle attachments of both types. Type 1 muscle attachments were seen in 85.9% of all the anterior disc displacement without reduction (ADD) TMJs (total 64 TMJs). Atrophy was seen in a higher proportion (43.7%) in TMJs with ADD (28/64) than in TMJs with normal and anterior disc displacement with reduction (ADDR). Out of 74 TMJs with atrophy, 68 had type 1 muscle attachment. Four TMJs had atrophy in both superior and inferior heads of the lateral pterygoid. However, atrophy was not present only in the ILPM. It has been concluded that since the SLPM only attached to the disc in type 1, the disc may displace anteriorly very easily. Therefore, this situation will reduce the function of the SLPM. Reduced muscle function may cause muscle atrophy. The activity of the SLPM may be more reduced since the disc permanently dislocated in TMJs with ADD. Finally, spasm of the LPM causes disc displacement and atrophy and then the degeneration of the LPM may follow disc displacement.