Biomechanical Comparison of Asymmetric Implant Configurations for All-on-Four Treatment Using Three-Dimensional Finite Element Analysis.

The aim of this study is to examine the effect of unilaterally more posterior placement of implants (Straumann BLT 4.1 mm in diameter and 12 mm long) applied according to the all-on-four concept on the stress distribution on bone, implants, and other prosthetic components, using the finite element analysis method. Three scenarios were modelled: For Model 1 (M1), anterior implants were placed symmetrically perpendicular to the bone in the right and left lateral incisor region, while the necks of the posterior implants placed symmetrically in the second premolar region were angled at 30 degrees. For Model 2 (M2) the implant in the left second premolar region was placed to the first molar region unilaterally. For Model 3 (M3) the implant in the left lateral incisor region was placed to the canine region unilaterally. Vertical and oblique forces (100 N) were applied in the right first molar region. The von Mises and maximum (Pmax) and minimum (Pmin) principal stresses were obtained. The highest stress concentration on the cortical bone was observed in the second premolar region in all models when oblique forces were applied. M1 was highest (8.992 MPa) followed closely by M3 (8.780 MPa) and M2 was lowest (3.692 MPa). The highest stress concentration on the prosthetic parts was observed in this framework when oblique forces were applied. M2 was highest (621.43 MPa) followed by M3 (409.16 MPa) and the lowest was M1 (309.43 MPa). It is thought that placing the implant further posterior to first molar region may prevent the bone resorption that occurs with high stress around the crestal bone. However, increased stress on the implants and prosthetic parts may lead to failures.

Effects of leukocyte- and platelet-rich fibrin alone and combined with hyaluronic acid on early soft tissue healing after surgical extraction of impacted mandibular third molars: A prospective clinical study.

PURPOSE: In this prospective, randomized, double-blind, controlled study, we evaluated the effects of leukocyte- and platelet-rich fibrin (L-PRF) alone and combined with hyaluronic acid (HA) sponge on early healing of soft tissue after mandibular third molar (M3) surgery. PATIENTS AND METHODS: In total, 60 patients aged 18-30 (mean 22.3), 22 male and 38 female, were included in this study. After surgical extraction of the impacted M3, L-PRF was applied to the socket in the L-PRF group (n = 20), and a combination of L-PRF and HA was applied in the L-PRF + HA group (n = 20). Nothing was applied in the control group (n = 20). The primary outcome variable was healing score for the mucosa over the extraction socket on the 7th, 14th, and 21st days. Secondary outcome variables were frequencies of postoperative complications: hemorrhagic complications, alveolar osteitis (AO), and postoperative wound infection. RESULTS: Mean healing scores for the mucosa on the 7th, 14th, and 21st days for both the L-PRF group and the L-PRF + HA group were significantly better than those for the control group. The ratio of alveolar osteitis for the control group was 1:20 and the ratio of postoperative wound infection for the control group was 1:20. There were no cases of alveolar osteitis or postoperative wound infection in the L-PRF and L-PRF + HA groups. No hemorrhagic complications were observed in this study. CONCLUSION: The results of this study suggest that L-PRF alone and when combined with HA can be an effective way to improve soft tissue healing, and could be used to prevent postoperative alveolar osteitis and infection after M3 surgery. Further studies with larger study groups are necessary.

Effects of Leukocyte- and Platelet-Rich Fibrin Alone and Combined With Hyaluronic Acid on Pain, Edema, and Trismus After Surgical Extraction of Impacted Mandibular Third Molars.

PURPOSE: In this prospective, randomized, double-blind controlled study, we evaluated the effects of leukocyte- and platelet-rich fibrin (L-PRF) alone and combined with a hyaluronic acid (HA) sponge on pain, edema, and trismus after mandibular third molar surgery. PATIENTS AND METHODS: In total, 60 patients were included in this study. The patients were randomly divided into 3 groups: L-PRF group (L-PRF was applied to the socket), L-PRF-plus-HA group (L-PRF combined with HA was applied to the socket), and control group (nothing was applied). The primary outcome variables were edema (tragus to pogonion, tragus to labial commissure, and angulus mandibulae to lateral canthus), trismus on postoperative days 2 and 7, and postoperative pain scores on a visual analog scale from hour 6 to day 7. RESULTS: After extraction, the tragus-to-pogonion values were significantly higher in the control group both on day 2 (higher than L-PRF-plus-HA group) and on day 7 (higher than both groups). The mean increase in tragus-to-labial commissure values on day 2 was significantly higher in the control group than in the L-PRF-plus-HA group. The mean increase in angulus mandibulae-to-lateral canthus values on days 2 and 7 was significantly higher in the control group than in the L-PRF and L-PRF-plus-HA groups. There was no significant difference among groups in trismus and visual analog scale pain scores. Analgesic intake on the day of surgery in the L-PRF-plus-HA group was significantly lower. CONCLUSIONS: Our results imply that L-PRF, particularly when combined with HA, can be used to minimize postoperative edema after mandibular third molar surgery. However, further studies with larger samples are required.