Analysis of radiologic factors in determining premolar root canal systems

OBJECTIVES: Certain tooth groups pose problems as to radiologic determination of root canal morphology. For example, the premolars may have superimposed roots that give the appearance of a single canal when 2 are actually present. This study examined the effect of X-ray tube inclination so as to visualize the complete root canal system in premolars. STUDY DESIGN: One hundred extracted premolars were divided into 4 groups of 25 teeth each: 1MxP (first maxillary premolar), 2MxP (second maxillary premolar), 1MdP (first mandibular premolar), and 2MdP (second mandibular premolar). A total of 10 radiographs were made of each tooth in the horizontal and vertical planes (horizontal angles of 0, 20, and 40 degrees, then vertical angles of 0, 15, and 30 degrees). Logistic regression analysis was used for the statistical analysis of the results--the dependent variable being the number of canals visualized. RESULTS: On varying the horizontal angle (20 and 40 degrees), the number of root canals observed in the case of 1MxP, 2MxP, and 1MdP coincided with the actual number of canals present. In the case of 2MdP, only the 40 degree horizontal angle correctly identified the number of canals regardless of the vertical angle (although only 4% had more than 1 canal). CONCLUSIONS: Varying the horizontal angle improved the visualization of additional (superimposed) canals in premolars. Changing of the vertical angle had no statistically significant influence except for the first mandibular premolars.     

Arteriovenous fistula after temporomandibular joint arthroscopy successfully treated with embolization

Temporomandibular joint arthoscopy is a minimal invasive surgical procedure commonly used to effectively treat some internal derangement of the TMJ. However, this method is not free of complications. Arteriovenous fistula (AVF) is a lesion that communicates the high flow arterial system and the low flow venous network. We describe a new case of preauricular traumatic AVF successfully treated with external carotid embolization, along with a review of the medical literature.     

Temporomandibular joint and masticatory muscle involvement in myotonic dystrophy: a study by magnetic resonance imaging

OBJECTIVE: The purpose of this study was to evaluate the masticatory muscles and the temporomandibular joint (TMJ) by magnetic resonance imaging (MRI) in myotonic dystrophy (MD) patients. STUDY DESIGN: MRI of the masticatory muscles and TMJ was performed in 15 MD patients, 11 male and 4 female, aged 16 to 53 years (mean, 31 years). Many of them had dental malocclusion, especially Angle class III and anterior open bite, and 3 complained of recurrent TMJ dislocation. TMJ and masticatory muscle pain was not observed, and joint sounds were noted in only 1 patient. RESULTS: The analysis of MRI scans showed masticatory muscle involvement in 13 patients (86.6%). In 11, the involvement was moderate to intense. The main abnormalities observed were increased intramuscular tissue signal on T1 (fatty infiltration) and volumetric reduction of muscles. Regarding the TMJ, articular disk displacement was seen in only 1 patient, but abnormalities of disk shape were common. Mild bone abnormalities were frequently observed, including changes of shape and contour of bone surface, and sclerosis of bone marrow. In 4 patients the condyle moved anterior to the eminence with the mouth opened fully (condylar hyperexcursion). CONCLUSIONS: This study shows that masticatory muscles are frequently and intensively affected in MD patients. Bone changes are the most consistent abnormalities observed in the TMJ. It is possible that remodeling is caused by biomechanical changes in the jaw as a result of masticatory muscle involvement.     

Trigeminal neuropathy

Trigeminal neuropathies (TNs) are well recognized disorders characterized and manifesting as skin and mucosal numbness in the region innervated by the trigeminal nerve. Facial numbness indicates trigeminal sensory alteration affecting the trigeminal system. TNs always pose differential location difficulties as multiple diseases are capable of producing them: they can be the result of traumatism, tumors, or diseases of the connective tissue, infectious or demyelinating diseases, or may be of idiopathic origin. Their importance is explained by the fact that TN may represent the first manifestation of tumor disease, or of relapse in patients with prior neoplastic processes. As such, these manifestations are ominous, and patient life expectancy is often short. The clinical exploration reveals a loss of sensitivity in the cutaneous territory corresponding to the affected nerve, which can be partial (hypoesthesia) or complete (anesthesia). The sensory defect is occasionally associated with hyperesthesia (i.e., the patient suffers a decrease in sensory perception, but when sensation is perceived, it may cause considerable discomfort). Complementary studies are needed to establish the etiologic diagnosis, with laboratory tests to discard the possible causative diseases underlying the trigeminal neuropathy, and the opportune radiographic examinations in the form of plain X-rays or a routine cranial computed tomography scan.     

Polymerization shrinkage and depth of cure of packable composites.

OBJECTIVE: This investigation evaluated polymerization shrinkage and depth of cure of five packable composites. METHOD AND MATERIALS: Five materials were used for the investigation: Alert, Surefil, Solitaire, P60, and Prodigy Condensable. Groups of 10 specimens of each material were made measuring either 2 or 5 mm in thickness, mounted in a testing jig, and polymerized using a dental curing light. Linear shrinkage was recorded and converted to a volumetric value. To evaluate depth of cure, ten specimens of each material were fabricated in both 2- and 5-mm thicknesses, and a Knoop hardness number was recorded on the top and bottom surfaces 5 minutes after light curing. A one-way analysis of variance statistical test was used to determine if there was a significant difference among materials. A Tukey multiple comparison test was then used to determine where significant differences existed. RESULTS: The volumetric shrinkage for the 2-mm-thick specimens from highest shrinkage to lowest were: Solitaire (3.3%), Prodigy Condensable (1.8%), Surefil (1.4%), P60 (1.2%), and Alert (0.2%). The 5-mm-thick specimens were ranked as follows: Solitaire (2.1%), Prodigy Condensable (1.0%), P60 (0.9%), Surefil (0.8%), and Alert (0.3%). Hardness for the bottom surface of the 2-mm-thick specimens showed that P60 (48.5) and Alert (42.6) had the highest values. Solitaire (11.2) had a significantly lower value. Hardness for the bottom surface at 5-mm thickness showed Alert (16.5) and P60 (16.3) with higher values than Surefil (8.9). CONCLUSION: Solitaire had the most shrinkage and Alert the least at both 2- and 5-mm depths. Depth of cure was severely compromised for all materials at 5 mm.     

Mandibular distraction osteogenesis in hemifacial microsomia: Long-term follow-up

AIM: Prospective, longitudinal, clinical long-term follow-up study of a homogeneous sample of children affected by hemifacial microsomia and treated by mandibular distraction osteogenesis. MATERIAL: Eight patients affected by types I and II hemifacial microsomia were operated on at an average age of 5.6 years with an average follow-up of 5.8 years. METHODS: Vertical changes were measured on postero-anterior cephalometric and panoramic radiographs taken sequentially. RESULTS: Angular changes of the infraorbital and nasal floor planes were not significant, showing that distraction osteogenesis starting after 5 years of age did not influence the maxillary skeletal base. Occlusal (plane) cant was reduced by 7 degrees on average following distraction osteogenesis, showing good dentoalveolar plasticity. Mandibular vertical changes showed a gradual return of the asymmetry, with growth in all patients (the ratio between affected and non-affected rami returned by 77% of the correction obtained by means of distraction 5 years postoperatively). CONCLUSION: Although aesthetic and psychological advantages of distraction osteogenesis are well accepted it should only be applied after careful patient selection and honest explanation of the long-term recurrence by genetically determined craniofacial growth patterns.     

Bone defect formation during implant placement following alveolar distraction

PURPOSE: This retrospective study was designed to evaluate the volume of hard tissue generated at the time of implant placement in distracted alveolar bone. MATERIALS AND METHODS: All patients who underwent distraction osteogenesis between 2000 and 2003 were included. The preoperative bone height, amount of distraction performed, and presence or absence of complications affecting implant placement were recorded. The augmentation achieved was correlated with insufficient bone formation using the Spearman correlation and the Fisher exact test. RESULTS: The study included 43 implants placed in 17 cases of alveolar distraction. Of the 34 implants placed in bone augmented by 4.5 to 6.5 mm, bone defects were observed with 12. All 9 implants placed in ridges augmented by 7 to 10.5 mm demonstrated a bone defect. The "defect" and "no-defect" implant groups differed significantly with respect to preoperative bone height and amount of distraction performed (P < .001 for both). Significantly more defects were formed in bone augmented by > 25% compared to bone augmented by < 25% (P < .001). CONCLUSIONS: When considering distraction osteogenesis, augmentation of up to 25% of the initial bone height seems more predictable and less likely to be associated with complications at the time of implant placement. In distractions greater than 25% of the original height, additional treatment should be considered.     

Evaluation of minipigs as an animal model for alveolar distraction

OBJECTIVE: Alveolar distraction osteogenesis is a relatively novel tissue regeneration technique that remains, in some respects, at an experimental stage. The selection of an experimental animal biomodel is not clearly defined, with reports in the reviewed literature on dogs, sheep, and monkeys. The present objective was to compare 2 experimental biomodels (dog and minipig) using an alveolar distraction protocol with a novel prototype distractor. STUDY DESIGN: Three beagle dogs and 3 G?ttingen minipigs were evaluated, placing the distractor at the right hemimandible alveolar ridge after previous extraction of premolars. The radiological examination was carried out immediately after the distraction and at 2 weeks of consolidation. RESULTS: Satisfactory clinical and radiological results were obtained in 2 of 3 beagle dogs after the previous unilateral extraction of mandibular and maxillary premolars. During the consolidation, a height gain of approximately 5 mm was observed, with the appearance of radiodense bone trabeculae in the distraction chamber. The distraction failed in all of the minipigs. CONCLUSION: The minipig was not an appropriate biomodel for the study of alveolar distraction because the investigators were not able to maintain the seal of the distraction chamber or the stability of the distractor.