Burak Bayram

Comparison of Fixation Stability of Resorbable Versus Titanium Plate and Screws in Mandibular Angle Fractures

PURPOSE The aim of this study was to compare the fixation reliability and stability of titanium and resorbable plates and screws by simulating chewing forces. MATERIALS AND METHODS Mandibular angle fractures in 11 sheep hemimandibles were fixed with 4-hole straight titanium plates and 2.0 x 7-mm titanium screws; in addition, 11 hemimandibles were fixed with 4-hole straight resorbable plates and 2.5 x 6-mm resorbable screws according to the Champy technique. The hemimandibles were mounted with a fixation device in a servohydraulic testing unit for compressive testing. Displacement values under 20, 60, 100, 120, 150, and 200 N; maximum displacements; and maximum forces that the model could resist before breakage were recorded and compared. RESULTS Significant differences were found between resorbable and titanium plates and screws at all forces (20, 60, 100, 120, 150, and 200 N) (P < .05). We found no statistically significant differences in the breaking force and maximum displacement values (displacement values at the breaking forces) between the groups. CONCLUSIONS The stability of mandibular angle fractures with titanium miniplates under simulated chewing forces was significantly higher than with the resorbable system. Metallic and resorbable fixation systems cannot be used interchangeably to treat mandibular angle fractures under similar loading conditions.

Effects of different mandibular fracture patterns on the stability of miniplate screw fixation in angle mandibular fractures

The aim of the present study was to evaluate the effects of horizontally favourable and unfavourable mandibular fracture patterns on the fixation stability of titanium plates and screws by simulating chewing forces. Favourable and unfavourable mandibular fractures on 22 sheep hemimandibles were fixed with 4-hole straight titanium plates and 2.0mm×7mm titanium screws according to the Champy technique. Hemimandibles were mounted with a fixation device in a servohydraulic testing unit for compressive testing. Displacement values under 20, 60, 100, 120, 150, 200N, maximum displacements, and maximum forces the model could resist before breakage were recorded and compared. The authors found no statistically significant differences between the groups for the displacement values in the force range 60-200N (60, 100, 120, 150 and 200N). Statistically significant differences for maximum displacement values (displacement values at the breaking forces) between the groups were found (P<0.05). There was no evidence for the need to apply different treatment modalities to mandibular fractures regardless of whether the factures are favourable or not.

Implant-Box Mandible: Dislocation of an Implant into the Mandible

p t p l H l t t o h m t m p i t r m p t s i s m i l D 1 l r ental implant surgery has become a highly predictble procedure; however, risks are still associated ith the surgical or restorative therapy phase. The ntraoperative complications of implant surgery have een previously described in detail. The wellnown intraoperative complications and accidents reated to surgery have included hemorrhage, nerve amage, mandibular fractures, damage to adjacent eeth, lack of primary stability, and displacement or igration of implants. The displacement of an implant will occur intraopratively or within a short period because of poor urgical technique or anatomic variances. In contrast, igration is the long-term relative motion of an imlant. In either case, the bone quantity and/or quality ill be compromised. Changes in intrasinal and nasal ressure, autoimmune reactions to the implant, and ncorrect distributions of the occlusal forces have een the mechanisms proposed to explain the imlant migration. The mechanisms to explain the intraperative and early displacement of dental implants ave not been fully clarified. Failure of primary imlant stability can result from low trabecular bone ensity, decreased thickness of the cortical bone, natomic variances, previous infection, osteopenia or steoporosis, and/or poor surgical technique, such as nadequate planning, overworking of the implant bed, ncorrect manipulation and mishandling have been uggested as possible factors. The displacement of dental implants into the maxllary sinus and migration into the sphenoid or ethoid sinus, nasal floor, or anterior cranial fossa has een previously reported. The anatomic features of the edentulous posterior axilla with the limited amount of bone available ith poor quality and pneumatization of the maxillary

Effects of Titanium Plate Fixation on Mandibular Growth in a Rabbit Model

PURPOSE The purpose of this study was to evaluate the effect of metallic rigid fixation of mandibular corpus fracture on mandibular growth in growing rabbits. MATERIALS AND METHODS Thirteen 90-day-old white New Zealand rabbits weighing 2 to 2.6 kg were included in this study. Unilateral mandibular fractures were created in all of the animals and fixed with microplates and screws. Microplates that had been adapted for fixation of the left (experimental) side were also used as a template for the drilling procedure on the right (control) side of the mandible. The plate was then removed, and screws were inserted. Digital submentovertex radiographs of each animal were taken before the operation and 6 months after surgery. Cephalometric values were analyzed. The distance between the centers of the 2 screws on the right side of the mandible was measured with a caliper in all samples, and values were compared with measurements taken from the left (experimental) side of the mandible upon which the plates had been placed. RESULTS The mean amount of mandibular growth was 4.38+/-2.43 mm on the right (control) side and 4.64+/-2.27 mm on the left (experimental) side. This difference was not statistically significant (P> .05). The distance between the 2 screws was 13.89+/-0.23 mm on the experimental side and 13.44+/-0.46 mm on the control side. This difference was statistically significant (P< .05). CONCLUSIONS Metallic fixation of a mandibular body fracture did not cause mandibular asymmetry or restricted mandibular growth in growing rabbits in this relatively small sample.

Change in Inferior Sclera Exposure Following Le Fort I Osteotomy in Patients With Midfacial Retrognathia

PURPOSE For facial esthetic reasons, no sclera should be exposed above or below the irises when the head of a patient who has a normal skeletal pattern is in a neutral position and the eyelids are in a relaxed position. This study evaluated the decrease in sclera exposure after maxillary advancement or impaction in patients with midfacial hypoplasia. PATIENTS AND METHODS Forty-seven consecutive patients (24 male, 23 female) who underwent Le Fort I osteotomy were included. The patients were divided into 2 groups according to type of maxillary movement: group I underwent maxillary advancement (n = 23) and group II underwent maxillary advancement and impaction surgery (n = 24). Standardized preoperative and 6-month postoperative photographs of the frontal view of patients were evaluated using Adobe Photoshop CS5. The proportion of inferior sclera exposure to eye height was determined, and the proportional difference between the preoperative and postoperative orbital views was statistically analyzed. RESULTS The proportion of inferior sclera exposure to eye height decreased by a ratio of 0.07 (P = .001) in the right and left eyes of the 47 patients, with an average maxillary advancement of 6.1 mm. The proportion of inferior sclera exposure to eye height of the right and left eyes decreased from 0.1 to 0.02 and from 0.09 to 0.02, respectively, in group I (P = .001). The proportion of inferior sclera exposure to eye height decreased in group II by a ratio of 0.06 in the right and left eyes (P = .001). CONCLUSION Inferior sclera exposure in patients with midfacial hypoplasia and retrognathia decreases significantly in accordance with the change in the lower eyelid position after maxillary advancement or impaction surgeries.

Is auditory function affected after Le Fort I osteotomy

The aim of this study was to evaluate changes to the Eustachian tube and middle ear function and hearing level in individuals undergoing Le Fort I osteotomy. 20 consecutive patients underwent Le Fort I maxillary osteotomy with advancement, impaction or a combination of both. All individuals underwent hearing sensitivity tests, including pure tone audiometry and acoustic impedance measurements (middle ear pressure and compliance), which were carried out by an audiologist 1 week before surgery (t(0)), and then again 1 week (t(1)) and 4 weeks (t(2)) after surgery. Regarding pure tone audiometry, the differences between t(0) and t(2) at a frequency of 125Hz (P=.002), between t(0) and t(1) and between t(0) and t(2) at a frequency of 250Hz, and between t(0) and t(1) at a frequency of 1000Hz (P=.006) were statistically significant. There was no statistically significant difference at any other frequency. Regarding middle ear pressure, no statistically significant difference was observed between t(0) and t(1), and t(0) and t(2). Following Le Fort I osteotomy, mild changes in hearing sensitivity and middle ear pressure are possible, but these changes were clinically insignificant.

Stress Distribution on Short Implants at Maxillary Posterior Alveolar Bone Model With Different Bone-to-Implant Contact Ratio: Finite Element Analysis

The aim of this study was to evaluate the stress distribution of the short dental implants and bone-to-implant contact ratios in the posterior maxilla using 3-dimensional (3D) finite element models. Two different 3D maxillary posterior bone segments were modeled. Group 1 was composed of a bone segment consisting of cortical bone and type IV cancellous bone with 100% bone-to-implant contact. Group 2 was composed of a bone segment consisting of cortical bone and type IV cancellous bone including spherical bone design and homogenous tubular hollow spaced structures with 30% spherical porosities and 70% bone-to-implant contact ratio. Four-millimeter-diameter and 5-mm-height dental implants were assumed to be osseointegrated and placed at the center of the segments. Lateral occlusal bite force (300 N) was applied at a 25° inclination to the implants long axis. The maximum von Mises stresses in cortical and cancellous bones and implant-abutment complex were calculated. The von Mises stress values on the implants and the cancellous bone around the implants of the 70% bone-to-implant contact group were almost 3 times higher compared with the values of the 100% bone-to-implant contact group. For clinical reality, use of the 70% model for finite element analysis simulation of the posterior maxilla region better represents real alveolar bone and the increased stress and strain distributions evaluated on the cortical and cancellous bone around the dental implants.

Does the titanium plate fixation of symphyseal fracture affect mandibular growth

Abstract The effect of metallic fixation on growth is a major concern in children and is not yet clear. The aim of this study was to evaluate the effect of metallic fixation of mandibular symphyseal fracture on mandibular growth. Eighteen 90-day-old growing white New Zealand rabbits weighing 1.6 to 2.5 kg were included in this study and divided into 2 groups of 9 subjects. In the experimental group, animals underwent mandibular osteotomy, simulating a symphyseal fracture on the midline of mandibular symphysis. The bone segments were fixed with microplates and microscrews (1.6 mm). In the control group, the same surgical incision without performing symphyseal osteotomy was conducted, and 2 screws were inserted on each side of the symphyseal midline. Digital cephalometric and submentovertex radiographs were taken before the operation and at postoperative 6 months for each animal in 2 groups, and cephalometric measurements were performed. The distance between the centers of the head of 2 screws measured at the end of surgery in the control group was compared with measurements at 6 months after surgery. Obtained data were statistically analyzed. There is no statistically significant difference between the 2 groups for growth amount of both sides of the mandible. Difference of ANS-Id (the most anterior points of nasal bone, the most anterior point on the alveolar bone between the lower incisors) and Cd-Id (the uppermost and most distal point of the mandibular condyle, the most anterior point on the alveolar bone between the lower incisors) values of the 2 groups is not statistically significant (P > 0.05). The distance between the 2 screws at the first application significantly increased at the postoperative sixth month (P < 0.05). Metallic fixation of mandibular symphyseal fracture does not affect the vertical and sagittal mandibular growth in growing rabbits.

Repositioning of the masseter muscle and its effect on skeletal growth

OBJECTIVE The aim of this study was to establish a model to aid in understanding the influences of bilateral masseter muscle relocation on the bone and muscle, and to determine the influences of bilateral masseter muscle relocation on mandibular growth pattern in rabbits. STUDY DESIGN Ten 3-month-old growing white New Zealand rabbits were included. Digital lateral cephalometric radiographs were obtained before operation and 6 months after surgery. The Co-Gn, gonial angle, FMA, ANS-Me, GoGn-SN, Y-axis, and Jarabak values were compared by using Student t test. RESULTS There was a statistically significant difference between the groups in the gonial angle (P < .05). Vertical height values (GoGn-SN, FMA, Y-axis, and ANS-Me) showed statistically significant increases in animals in the control group. In contrast, vertical height values in the experimental group did not show statistically significant increase. CONCLUSIONS Anterior relocation of the masseteric muscle influenced the direction of vertical growth significantly compared with the control group.

Alveolar Ridge Splitting Versus Autogenous Onlay Bone Grafting: Complications and Implant Survival Rates

Purpose: To compare the complications and implant survival rates of localized alveolar ridge deficiencies in the horizontal dimension reconstructed by alveolar ridge splitting (ARS) or autogenous onlay bone grafting (OBG). Materials and Methods: Twenty-eight ARS and 28 OBG were performed. The survival rate of the all included implants was evaluated using the clinical and radiographical evaluation criteria of Misch et al. Temporary exposure of graft, mild infection, temporary paresthesia, and bad split were defined as minor complications; permanent exposure of graft, loss of graft, and permanent paresthesia were defined as major complications. Major and minor complications of ARS and OBG groups were statistically compared. Results: When the minor and major complication rates are considered, there was not any statistically significant difference between OBG (P = 0.099) and ARS (P = 0.241) groups. The satisfactory survival rate of OBG group was 92% and was 100% in the ARS group, and the difference was not statistically significant (P = 0.116). Conclusion: When reconstructing vertically sufficient but horizontally insufficient alveolar ridges, ridge splitting technique could shorten the treatment period, decrease postoperative swelling and pain, eliminate the need for a second surgical site, reduce the treatment cost, and ease the patient cooperation to the surgery.