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.

Evaluation of Patient Comfort and Impact of Different Anesthesia Techniques on the Temporomandibular Joint Arthrocentesis Applications by Comparing Gow-Gates Mandibular Block Anesthesia with Auriculotemporal Nerve Block.

Aim: Temporomandibular disorders (TMDs) are clinical situations that are characterized by pain, sound, and irregular movements of the temporomandibular joints. The most common method in the treatment of TMDs is arthrocentesis. This study aims to compare the effect of conventional extraoral auriculotemporal nerve block (ANB) and Gow-Gates (GG) mandibular anesthesia techniques on patient comfort in an arthrocentesis procedure. Materials and Methods: We performed this study on 40 patients who underwent TMJ arthrocentesis with ANB (n = 20) or GG (n = 20) mandibular anesthesia techniques at the Marmara University Faculty of Dentistry between 2016 and 2019. The predictor variable was the type of an anesthesia technique, and the outcome variables included were pain, maximum mouth opening (MMO), and protrusive movement (PM). They were compared at the preoperative period and 3rd and 6th month periods. Statistical analysis included means with standard deviations, a one-way ANOVA for continuous data, and the results were evaluated at the significance level of p < 0.05. Results: No statistically significant difference was observed between the VAS values, MMO, and PM averages of preoperative, 3rd and 6th months of ANB and GG (p=0.142, p=0.209, and p=0.148). Conclusion: Both anesthesia techniques have provided effective results in terms of pain and functional jaw movements in the postoperative period in arthrocentesis treatment.

Retrospective examination of complications observed in orthognathic surgical surgery in 85 patients.

BACKGROUND: The aim of our study is to examine the possible complications, risk factors, and solutions encountered in orthog-nathic surgery in the light of the cases; we performed in our clinic. METHODS: This study includes a retrospective analysis of the records of 85 patients who underwent orthognathic surgery between 2015 and 2020 in Istanbul Pendik District Hospital Oral and Maxillofacial Surgery Service. The types of complications encountered during the operations were recorded in the study. Independent variables such as gender, age, number of operations, surgical site, and type of osteotomy were evaluated. Complications were evaluated according to the Clavien-Dindo classification. The data were pre-sented for statistical analysis with a significance level of 0.05. RESULTS: Of the 85 patients included in the study, 40 were male and 45 were female. Of these patients, 65 had double chin operation and 20 had single chin operation. A total of 150 jaw osteotomies were performed, 78 of them in the maxilla and 72 in the mandible. While the maxilla was operated in 13 of the cases, in which single jaw operation was performed, only the mandible was treated in 7 of them. Complications were observed in 24 (10.57%) of a total of 227 osteotomies. Among the complications encountered, bleeding (8), nerve damage (7), malocclusion (3), infection (2), TMJ problems (2), bad split (1), and deviation at the tip of the nose (1) stand out, while complications were observed equally in men and women, complications were observed more frequently in cases with longer operative time (p<0.05). Complications were observed more frequently in bilateral sagittal split osteotomies (p<0.001) compared to Le Fort 1 osteotomies. Clavien-Dindo grade I complications were most common (72.04%) depending on the treatment. According to the Clavien-Dindo classification, there was no relationship between gender, age, duration of surgery, length of hospital stay, or surgical site, and the degree of complications (p≥0.05). CONCLUSION: Post-operative malocclusion, bleeding, inferior alveolar nerve injury, infection, poor division, and infection are the most common complications in orthognathic surgery. It can be associated with factors such as the duration of the operation, the number of operations, the site of the operation, and the type of osteotomy which performed. It is thought that positive contributions can be made to the success of the surgery by considering these factors in the treatment planning, during the operation and in the post-operative follow-up part.

Retromandibular transparotid approach for subcondylar mandibular fractures: A retrospective study.

BACKGROUND: The aim was to evaluate the effectiveness and complications of retromandibular transparotid approach performed for the reduction of dislocated subcondylar fractures. METHODS: Fourteen patients with subcondylar mandibular fractures were evaluated (8 male, 6 female, age range 19-43 years). The primary predictor variable in the present study was time (preoperative vs postoperative). The primary outcome variables were inflammatory complication, facial nerve deficit (House and Brackmann classification), and presence of parotid fistula. The secondary outcome variables were occlusal disturbances, maximal interincisal opening (MIO), and temporomandibular joint (TMJ) pain (VAS). RESULTS: Excellent occlusion and function was observed postoperatively. One salivary fistula occurred after surgery but was healed after 3 weeks. No inflammatory complication was observed. Three patients had grade III and one patient had grade II facial nerve deficit, all recovered in 6 weeks. All patients were free of pain and no malocclusion was observed. MIO was ranging from 34 to 58 mm (mean 44.4 mm) after 6 months. CONCLUSION: The retromandibular transparotid approach is feasible and safe. It facilitates reduction and fixation of subcondylar fractures with functional outcomes and rare complications.

Analyses of anatomical relationship between mandibular third molar roots and variations in lingual undercut of mandible using cone-beam computed tomography.

BACKGROUND/PURPOSE: Anatomical features of the lingual undercut region is a potential factor that might increase the risk of displacement of a tooth or fragment. The aim of this study was to report the normal anatomical relationship of impacted lower third molar roots to the lingual cortex and soft tissues of mandible and anatomical variations of lingual balcony in the impacted third molar region. MATERIALS AND METHODS: One hundred impacted third molars (54 males, 46 females) from 65 (31 men, 34 women) patients were evaluated for this study using cone-beam computed tomography. Three measurements [bone thickness, angle (Ang) 1 and Ang 2] were recorded on the coronal section slices of cone-beam computed tomography images; in these images, the impacted third molar root was closest to the lingual soft tissues. RESULTS: The average distance between the tooth root and the lingual outer cortical bone layer (bone thickness) was 1.03 mm. The averages of Ang 1 and Ang 2 were 140.61° and 153.44°. Ang 1 and Ang 2 of female patients were larger than those of male patients. CONCLUSION: The narrow angulation of the lingual balcony region and the relationship between roots and lingual soft tissues should be noted to avoid undesirable complication of displacement of a tooth or fragment into sublingual, submandibular, and pterygomandibular spaces. There was no relation in the floor of the mouth between the position of the impacted third molar roots and different lingual undercut angulation variations.

Implant Rehabilitation for Extremely Atrophic Maxillae (Cawood Type VI) with Le Fort I Downgrafting and Autogenous Iliac Block Grafts: A 4-year Follow-up Study.

PURPOSE: The aim of this 4-year retrospective follow-up study was to investigate treatment outcomes, including implant survival rate and marginal bone loss, in patients with maxillary Cawood type VI atrophy pattern who underwent Le Fort I downgrafting and iliac block augmentations for implant rehabilitation. MATERIALS AND METHODS: Retrognathic edentulous Class III patients with severe maxillary resorption (Cawood VI) were enrolled. Reconstructive procedures performed included Le Fort I maxillary osteotomy, iliac block grafting, labial sulcoplasties, and dental implant placement. Panoramic radiographs were used to assess marginal bone loss. The Nobel Biocare Replace and GMI Frontier dental implant systems and fixed partial dentures were used for dental rehabilitation. Statistical analyses were made using NCSS 2007 statistical software, with significance set at P < .05. RESULTS: Ten patients (six men and four women) with a mean age of 50.4 ± 12.55 years underwent maxillary osteotomy (advancement: 9 ± 1.4 mm; inferior repositioning: 8 ± 1.0 mm) and iliac block sandwich grafting (posterior ilium: n = 3; anterior ilium: n = 7) from 2009 to 2015. Nine patients were treated with a two-stage protocol. The mean graft healing period was 5.9 ± 0.73 months. A total of 98 implants were placed, 80 in maxillae and 18 in mandibles. The Nobel Biocare Replace system was used in two patients (n = 29 implants) and GMI Frontier system was used in eight patients (n = 69 implants). Implant numbers in the maxilla were: 6 implants in 2 patients, 8 implants in 6 patients, and 10 implants in 2 patients. The mean follow-up period was 47.8 ± 3.4 months. The success rate was 93.75%, with a 6.25% fail ratio (n = 9 implants) at a follow-up of 4 years. Marginal bone resorption was 1.8 ± 1.0 mm at the postoperative year 1 and 3.75 ± 0.85 mm at postoperative year 4. Marginal resorption in the 8-implant group was found to be higher than that in the 6-implant group and 10-implant group at the postoperative year 1 (P = .045, P = .026, P < .05, respectively). CONCLUSION: Le Fort I osteotomy and simultaneous iliac block grafting (downgrafting) is a valuable option for implant rehabilitation in extremely atrophic maxillae (Cawood VI). It showed a high survival rate (93.75%) at 4 years of follow-up in this study.

Bone healing after biodegradable mini-plate fixation.

PURPOSE: To compare bone healing in mandibular vertical body osteotomies (MVBO) after fixation with a resorbable 2.0mm-profile fixation system in the first and third postoperative months in rabbits. METHODS: Twenty hemimandibles of ten rabbits were divided into two groups according to duration of resorbable fixation-one or three months. The MVBOs were performed and one four-hole, resorbable, 2.0mm mini-plate fixation system was used on each side. The computed tomography (CT) scans, scanning electron microscopy (SEM), and histomorphometric outcomes of groups I and II were compared. RESULTS: Significant differences were found between the one- and three- month assessments in terms of newly formed bone ratio values (p<0.05). There was more new bone formation at the third month on both the CT and histomorphometric examinations. A better adaptation of the bone tissues to the resorbable mini-plate and screws was observed on SEM at three months. CONCLUSION: The resorbable mini-plates provided a fixation stable enough to allow immediate oral alimentation and callus formation in both groups.

Bone healing after biodegradable mini-plate fixation

ABSTRACT PURPOSE: To compare bone healing in mandibular vertical body osteotomies (MVBO) after fixation with a resorbable 2.0mm-profile fixation system in the first and third postoperative months in rabbits. METHODS: Twenty hemimandibles of ten rabbits were divided into two groups according to duration of resorbable fixation-one or three months. The MVBOs were performed and one four-hole, resorbable, 2.0mm mini-plate fixation system was used on each side. The computed tomography (CT) scans, scanning electron microscopy (SEM), and histomorphometric outcomes of groups I and II were compared. RESULTS: Significant differences were found between the one- and three- month assessments in terms of newly formed bone ratio values (p<0.05). There was more new bone formation at the third month on both the CT and histomorphometric examinations. A better adaptation of the bone tissues to the resorbable mini-plate and screws was observed on SEM at three months. CONCLUSION: The resorbable mini-plates provided a fixation stable enough to allow immediate oral alimentation and callus formation in both groups.

Hyaluronic Acid Versus Ultrasonic Resorbable Pin Fixation for Space Maintenance in Non-Grafted Sinus Lifting.

PURPOSE: An ultrasonic resorbable pin (SonicWeld, KLS Martin, Mühlheim, Germany) was compared with hyaluronic acid (Hyaloss Matrix, Anika Therapeutics, Bedford, MA) for their ability to maintain space in non-grafted sinus lifting. MATERIALS AND METHODS: A comparative split-mouth study was designed and implemented. Six women and 4 men were included (mean age, 56.7 yr). The primary predictors hyaluronic acid (HA) application and ultrasonic resorbable pin fixation (URPF) were coded as binary variables. The primary outcome variables were height of alveolar bone (HAB) and reduction in sinus volume (RSV). Secondary outcomes were bone density and implant survival. RESULTS: The postoperative mean HAB was significantly higher than the preoperative mean HAB on the 2 sides (P < .05). Mean increases in HAB and RSV on the URPF side were significantly greater than those on the HA side (P < .05). In total, patients were treated with 40 implants. No type I bone quality was identified; 14 (35%) implants were inserted in type II bone, 22 (50%) in type III bone, and 6 (15%) in type IV bone. There was no statistically meaningful difference between the 2 sides for implant survival or bone quality. At 6 months, all implants were clinically stable and the definitive prostheses were functional, resulting in a survival rate of 100%. CONCLUSIONS: There was sufficient bone height to eventually place implants on the 2 sides in all patients. The 2 techniques yielded predictable outcomes in implant survival and bone quality. However, HAB and RSV were considerably greater on the URPF side.