Cone beam computed tomography-based cephalometric norms for Brazilian adults.

This study established cone beam computed tomography (CBCT)-based cephalometric norms for Brazilian adults, including the assessment of sexual dimorphism. An observer performed McNamara's cephalometric analysis twice on 60 CBCT datasets acquired from patients with a normal dental occlusion, divided equally into two groups by sex. Welch's t-test was applied to assess differences between the sexes in hard tissue cephalometric measurements, and Dahlberg's formula was used to calculate measurement error introduced by the observer. The cephalometric measurements of effective mandibular length, effective midfacial length, maxillomandibular differential, and lower anterior facial height presented sexual dimorphism. Linear measurements had error ≤0.78mm, and angular measurements had error ≤1.24°. The results show that (1) the CBCT-based cephalometric norms established in this study are reliable for use by researchers and clinicians, and (2) Brazilian adult males and females have similar craniofacial morphology, with males possessing larger jaws than females.

Nasal airway evaluation in obstructive sleep apnoea patients: volumetric tomography and endoscopic findings.

Obstructive sleep apnoea (OSA) results from the recurrent collapse of the upper airway during sleep. Nasal abnormalities influence the stability of the pharynx. The aim of this study was to evaluate the volumetric and anatomical changes of the nasal cavity in patients with OSA. The Nasal Obstruction Symptom Evaluation (NOSE) scale was used to grade nasal obstruction. Sleep-related breathing disorders were evaluated by polysomnography. The nasal airway volume was obtained from computed tomography scans through volumetric reconstruction of the nasal airway. Alterations to the nasal anatomy were identified by nasal fibre-optic endoscopy. Ninety-four patient charts were analyzed. The final sample comprised 32 patients with severe OSA, 16 with moderate OSA, 23 with mild OSA, and 20 without OSA. Three groups were established based on nasal obstruction and OSA. The groups were compared for nasal airway volume (P=0.464) and body mass index (P=0.001). The presence of nasal septum deviation and inferior turbinate hypertrophy were related to the NOSE score (P=0.05 for both), apnoea-hypopnoea index (P=0.03 and P=0.05, respectively), and nasal airway volume (P=0.71 and P=0.78, respectively). In this nasal airway evaluation of OSA patients, the presence of sites of obstruction was correlated with the severity of OSA; this was not the case for the evaluation of the nasal airway volume dimensions.

Nasolabial changes after two different approaches for surgically assisted rapid maxillary expansion.

This retrospective study evaluated the nasolabial changes in patients who underwent surgically assisted rapid maxillary expansion (SARME) using two different approaches. Nineteen patients were included in the study, divided into two groups according to the kind of surgical approach performed: group 1 (n=9), SARME performed through the standard Le Fort I circumvestibular approach followed by the alar base cinch, and group 2 (n=10), SARME performed through a subtotal vestibular approach associated to a V-shaped incision at the maxillary midline in the labial frenulum region, without alar base cinch. Measurements of width, length, and nasal projection as well as upper lip length were taken from cone beam tomographic images obtained before surgery (T1) and 6 months postoperatively (T2). Both groups presented an increase in the alar base width postoperatively (P<0.05). The approach used in group 2 resulted in smaller changes in the alar base width as measured at the superior alar curvature (P<0.05). Nasal length and projection and upper lip length were not altered by SARME. The type of surgical approach influenced nasolabial changes, but did not eliminate increase in width of the alar base.

Finite element evaluation of three methods of stable fixation of condyle base fractures.

The surgical treatment of mandibular condyle fractures currently offers several possibilities for stable internal fixation. In this study, a finite element model evaluation was performed of three different methods for osteosynthesis of low subcondylar fractures: (1) two four-hole straight plates, (2) one seven-hole lambda plate, and (3) one four-hole trapezoidal plate. The finite element model evaluation considered a load applied to the first molar on the contralateral side to the fracture. Results showed that, although the three methods are capable of withstanding functional loading, the lambda plate displayed a more homogeneous stress distribution for both osteosynthesis material and bone and may be a better method when single-plate fixation is the option.

Orthognathic surgery with or without induced hypotension.

This study involved a retrospective evaluation of patients subjected to surgery for dentofacial deformities treated without induced controlled hypotension (group I, n=50) and a prospective evaluation of patients who were subjected to surgery under hypotensive general anaesthesia (group II, n=50). No statistical differences were found between the study groups with regard to the duration of surgery. However, there were statistically significant differences in the need for blood transfusion and the occurrence of bradycardia during the maxillary down-fracture. Hypotensive anaesthesia decreased the need for a blood transfusion and the occurrence of bradycardia, and is therefore considered highly beneficial for patients undergoing orthognathic surgery.

In vitro biomechanical evaluation of sagittal split osteotomy fixation with a specifically designed miniplate.

Recent studies have evaluated many methods of internal fixation for sagittal split ramus osteotomy (SSRO), aiming to increase stability of the bone segments while minimizing condylar displacement. The purpose of this study was to evaluate, through biomechanical testing, the stability of the fixation comparing a specially designed bone plate to other two commonly used methods. Thirty hemimandibles were separated into three equal groups. All specimens received SSRO. In Group I the osteotomies were fixed with three 15 mm bicortical positional screws in an inverted-L pattern with an insertion angle of 90°. In Group II, fixation was carried out with a four-hole straight plate and four 6mm monocortical screws. In Group III, fixation was performed with an adjustable sagittal plate and eight 6mm monocortical screws. Hemimandibles were submitted to vertical compressive loads, by a mechanical testing unit. Averages and standard deviations were submitted to analysis of variance using the Tukey test with a 5% level of significance. Bicortical screws presented the greatest values of loading resistance. The adjustable miniplate demonstrated 60% lower resistance compared to bicortical screws. Group II presented on average 40% less resistant to the axial loading.

Anatomic study of the mandibular foramen, lingula and antilingula in dry mandibles, and its statistical relationship between the true lingula and the antilingula.

The authors verified the anatomical location of the mandibular foramen, lingula and antilingula in dry mandibles, aiming to obtain information that could be used when performing mandibular osteotomies. Forty-four mandibles (88 sides) were evaluated. The distances were measured using a sliding calliper, with the mandibles fixed in a reproducible position. Results showed that the mandibular foramen is on average 5.82 mm below the lingula. Regarding the statistical comparison between the mandibular foramen entrance and the antilingula position, there is no correlation between the position of those two structures in the studied sample. The mandibular foramen is slightly posterior in relation to the centre of the ramus. The lingula is an important anatomic landmark for ramus surgery, and for determining the distance to the mandibular foramen entrance. The use of the antilingula as a landmark for the position of the vertical ramus osteotomy is not recommended.

Traumatic carotid cavernous fistula associated with a mandibular fracture.

Carotid cavernous sinus fistula is an abnormal vascular interconnection between a branch of the carotid artery and the cavernous sinus. This is an uncommon complication of craniofacial injuries, as it occurs in only 0.17-0.27% of cases, according to the literature. The differential diagnosis should include superior orbital fissure syndrome, orbital apex syndrome, orbital haematoma and cavernous sinus thrombosis. The case is reported of an 18-year-old white woman who was involved in a motor vehicle accident. Clinical examination revealed only mandibular fractures, with the absence of skull-base, mid-face or any other fractures. Two days after the trauma, her condition deteriorated, and extraocular movements were totally absent. Magnetic resonance angiographic scanning was performed, and a carotid cavernous sinus fistula was found. This was treated by embolization resulting in restoration of eye movement and vision.

Comparison of peri-implant bone level assessment in digitized conventional radiographs and digital subtraction images.

OBJECTIVES: Radiographic assessment of marginal bone height is included in longitudinal control of osseointegrated implants. However, accurate and reproducible results are difficult to obtain. The aim of the present study was to examine the differences between linear measurements in digitized radiographs (DR) and digital subtraction images (DSI) around endosseous implants and the interobserver variability. METHODS: The bone height around 30 implants in 22 patients was assessed by 5 observers. Standardized periapical radiographs were obtained just after the surgery and 4 months later. The radiographs were digitized and manipulated by means of EMAGO software, and linear and logarithmic DSIs were produced. Furthermore, the logarithmic subtraction was enhanced with the use of a filter. The observers had the DRs and three methods of subtraction to assess bone height. ANOVA statistical procedures were applied to analyse differences between the observers in the four assessed images and the Tukey test was used to evaluate the differences between the images. RESULTS: Comparison of the bone height assessments indicated significantly (P<0.05) higher values in the DR than the three methods of DSI. The observers also had a statistically significant variability in this assessment (P=0.00003). CONCLUSIONS: DSI demonstrated lower values of linear measurements of the bone height around endosseous implants, compared with DR. Interobserver variability should be considered when comparing values from follow-up studies.

Evaluation of different treatments for oroantral/oronasal communications: experience of 112 cases.

This retrospective study analyzed the etiologic factors, location and treatments for patients with oroantral or oronasal communications (OAC or ONC). Data analysis extended to gender, age, etiology, location, type of treatment and short-term complications from January 1988 to May 2004. A total of 112 patients with 101 (90%) OAC and 11 (10%) ONC were included. The main etiology for OAC was tooth extraction (95%) with similar prevalence between right (49%) and left (51%) side. For ONC, pathological conditions (27%) and exodontia (27%) were the most prevalent. For the treatment of OAC, suture was the technique most frequently used (60%), followed by buccal fat pad (28%), buccal flap (9%), palatal flap (2%) and one dental transplant (1%). For ONC, the following treatments were used: suture (46%), buccal flap (36%) and palatal flap (18%). Failure to eliminate the communication occurred in six (6%) patients of the OAC group and three (27%) of the ONC group. The results confirm that tooth extraction was the most common etiologic factor for ONC and OAC. Suture, when the communication was small (3-5 mm), and the use of a buccal fat pad (100% successful), when a larger communication existed (>5 mm), seemed to be the two best choices for treatment.

Complications of nonrigid fixation of mandibular angle fractures.

This retrospective study analyzed complications in 96 patients with 99 mandibular angle fractures treated during a 3-year period with either closed reduction or nonrigid means of fixation combined with maxillomandibular fixation. An overall complication rate of 17% occurred. Infection was the most common complication, occurring in 17 fractures. Thirteen fractures had infection as the only complication; in the remaining four patients, infection was combined with malunion/malocclusion. The results of this study show that mandibular angle fractures in an inner-city population are associated with a high incidence of postsurgical complications.

Relationship of substance abuse to complications with mandibular fractures.

This retrospective study analyzed the relationship between complications and substance abuse following mandibular fracture. Over a 2-year period, the records of 352 patients with 589 mandibular fractures were reviewed for methods of treatment and other variables, including chronic abuse of drugs. An overall complication rate of 18.5% was found. Positive associations between complications and chronic abuse of alcohol and nonintravenous and intravenous drugs were found. Intravenous drug abusers had a 30%, nonintravenous drug abusers had a 19%, and chronic alcohol abusers had a 15.5% incidence of complications. Those individuals who did not use any drug chronically had a 6.2% complication rate. The results of this study show that chronic substance abuse can significantly affect treatment outcomes for management of mandibular fractures.