Determination of the N=16 shell closure at the oxygen drip line.

The neutron unbound ground state of (25)O (Z=8, N=17) was observed for the first time in a proton knockout reaction from a (26)F beam. A single resonance was found in the invariant mass spectrum corresponding to a neutron decay energy of 770_+20(-10) keV with a total width of 172(30) keV. The N=16 shell gap was established to be 4.86(13) MeV by the energy difference between the nu1s(1/2) and nu0d(3/2) orbitals. The neutron separation energies for (25)O agree with the calculations of the universal sd shell model interaction. This interaction incorrectly predicts an (26)O ground state that is bound to two-neutron decay by 1 MeV, leading to a discrepancy between the theoretical calculations and experiment as to the particle stability of (26)O. The observed decay width was found to be on the order of a factor of 2 larger than the calculated single-particle width using a Woods-Saxon potential.

Clear cell carcinoma of the palate.

A case of minor salivary gland clear cell adenocarcinoma of the palate with metastasis to the lungs in a 53-year-old female is presented. Histologically, the cells were characterized by glycogen rich clear cells arranged in solid nests, trabeculae, surrounded by hyalinized fibrous stroma. We believe this represents an aggressive form of this type of tumor.

Alcohol withdrawal syndrome: current management strategies for the surgery patient.

PURPOSE: As advances in the therapeutic management of alcohol withdrawal syndrome occur, oral and maxillofacial surgeons should be aware of the current treatment philosophies and modalities. This article provides a comprehensive review of alcohol withdrawal syndrome and presents some of the current management strategies that can be used for these patients, whether it be in the office or in the hospital.

Surgical documentation form for TMJ arthroscopy.

The use of a form to document the findings observed during arthroscopy of the temporomandibular joint will allow oral and maxillofacial surgeons not only to consistently record the abnormal observations but also to compare their findings with the findings of other surgeons and possibly even establish a national database. The form presented has been used by the author for 6 years with periodic modification and has provided a means to review and evaluate surgical findings in patients who had arthroscopic procedures.

Efficacy of temporomandibular joint arthroscopy: a retrospective study.

One hundred fifty temporomandibular joints (TMJs) in 109 patients underwent arthroscopic surgery with lysis, lavage, and debridement. The patients were evaluated for preoperative and postoperative interincisal opening, lateral and protrusive excursions, and pain. There was general improvement in all categories, with a reduction of pain to a level that was manageable in 93% of the patients. Temporomandibular arthroscopic surgery is an effective procedure, improving TMJ hypomobility and reducing pain.

Bone hole diameter as a function of drill guide length and drilling method in rigid internal fixation.

This study examines drill guide length and drilling method to see which technique produces the most accurate hole diameter. Two hundred twenty-five holes were produced in fresh porcine mandibles and then measured with a micrometer. A long guide, a short guide, and no guide were used with a drill press, a pneumatic drill, and a manual drill. Using a 2-mm drill bit, the overall average diameter was 2.03 mm and the overall range was 1.85 mm to 2.60 mm. Statistical analysis of the data indicates the drilling method and the guide length made no difference in the hole diameter at the 95% level (P = .05).

Assessment of Proplast-Teflon disc replacements.

This retrospective study reports the findings in the follow-up of 31 temporomandibular joints in which Proplast-Teflon (Vitek Inc, Houston, TX) replacements were used. Among the problems noted were pain, malocclusion, restricted opening, and degenerative changes in the condyle and fossa.

Mechanical behavior of mandibular continuity defects reconstructed using combinations of hydroxylapatite and autogenous bone.

The purpose of this investigation was to determine the mechanical behavior of primate (Macaca mulatta) mandibles with continuity defects reconstructed using varying ratios of an alloplastic hydroxylapatite (HA) implant material mixed with autogenous bone (AB). The defects were allowed to heal for 6 and 18 months before killing the animals and mechanical testing. Each animal had one side of the mandible restored with 100% AB as control. The fracture strength and section modulus of the opposite side of the mandible, containing the test ratio of HA-AB, were directly compared with the mechanical behavior of the control side. The fracture strength and section modulus were evaluated by a cantilever type of mechanical test that took into account the anisotropic, viscoelastic, and geometric nature of the mandible. The type of bone and tissue at the fracture site was examined by scanning electron microscopy and a direct correlation between the amount of bone and/or fibrous tissue growth around the HA implant material and the fracture strength and section modulus values was established. The average fracture strength of the AB graft sites at 18 months was 9,975 +/- 4,300 psi, with ratios of 25:75 and 50:50 HA-AB giving test results approaching those of the AB graft sites.

Restoration of mandibular continuity defects using combinations of hydroxylapatite and autogenous bone: microscopic observations.

The purpose of this investigation was to assess by light, transmission, and scanning electron microscopy the healing of mandibular continuity defects reconstructed with varying ratios of an alloplastic hydroxylapatite implant material (HA) mixed with autogenous bone (AB). This study reports the microscopic observations of implant and control sites at 6 and 18 months postsurgery. The results confirm the biocompatibility of dense HA granules. Specimens exhibited differing degrees of osseous regeneration that appeared related to the percent composition of HA. At 18 months, 86% and 91% of the HA granules were completely surrounded by bone in those specimens reconstructed with implants consisting of 25% and 50% HA, respectively. In contrast, specimens receiving implants consisting of 75% and 100% HA features osseous encapsulation of 75% and 66% of the granules, respectively. The results of this limited study indicate that dense HA granules mixed with AB in ratios ranging from 3:1 to 1:1 (AB:HA) may be successfully used as a bone extender during reconstructive surgery.

Surgery of the temporomandibular joint: facial nerve injury with modified dissection technique.

This paper describes a modified preauricular surgical approach to the TMJ used in more than 272 joint surgeries since October 1984. During this time, only four surgical procedures have resulted in postsurgical paresis of the frontal branch of the facial nerve. The technique is a modification of the preauricular approaches described by Al Kayat, Bramley, and Dolwick. Relevant anatomic studies that relate to the frontal branch of the facial nerve and associated fascial layers are discussed. From findings of current anatomic dissections, a safe preauricular approach to the TMJ is described, with emphasis on following certain landmarks.

Temporomandibular disorders: what to teach in dental school.

Temporomandibular joint disorders continue to be a nemesis for health professionals and for patients who are afflicted. The medical/dental student must be taught to recognize this often complex disorder and be able to interact with the various disciplines within the medical/dental profession to provide the care needed. This article discusses problems and a possible approach for establishing continuity of format for classifying TM disorders so students can be taught to recognize them.

Nutrition and the head and neck cancer patient.

Patients with head and neck cancer have a unique nutritional problem that can affect their response to treatment. To properly manage these patients the oral and maxillofacial surgeon must be able to accurately assess their nutritional status and implement the proper metabolic treatment. This article reviews the benefits of nutritional support, the methods of patient assessment and nutritional repletion, and the advantages and disadvantages of the various alimentation modalities. Also, an analysis of the relationship of nutritional status and the surgical course of the head and neck cancer patient at our institution is presented.

Bilateral mandibular dentigerous cysts in a five-year-old child: report of a case.

This is the youngest patient reported in the literature with bilateral mandibular dentigerous cysts. This report confirms the importance of a panoramic radiographic examination in diagnosing bony lesions of the jaws. Early diagnosis and aggressive treatment of these lesions is essential to avoid the undesirable sequelae that could occur without treatment. Dentigerous cysts are bony lesions that have the potential to produce neoplasms.

Extubation criteria for oral and maxillofacial surgery patients.

An overview is presented of some of the factors that should be considered before extubating a patient who has undergone an oral and maxillofacial surgical procedure. A discussion of the possible preoperative assessment of the patient, complications of intubation, effects of narcotics and muscle relaxants, assessment of airway edema, and criteria for extubation is included.

Synovial chondromatosis of the temporomandibular joint: report of two cases.

Two cases of synovial chondromatosis of the temporomandibular joint are reported. This condition is rare but benign, with only 36 cases reported in the literature to date. Symptoms include tenderness, swelling, and limited range of motion, with deviation to the affected side. Diagnosis is made both from the clinical presentation and histologic examination. The etiology is thought to be cartilaginous foci within the synovial membrane that become detached and proliferate in the synovium as chondrocytes. Treatment includes removal of the "loose bodies" and possible resection of the synovial membrane, condyle, and disk.