Effects of varying mandibular protrusion and degrees of vertical opening on upper airway dimensions in apneic dentate subjects.

INTRODUCTION: Despite numerous studies investigating the dimensional and therapeutic effects of mandibular advancement splints (MASs), data regarding the effects of differently designed individual and non-adjustable MASs on the upper airway in fully dentate apneic subjects in the sagittal plane including comparison of these effects with a placebo device are sparse. The present study aimed to determine the dimensional changes in the sagittal plane created by differently designed MASs in the upper airway in fully dentate apneic subjects and to compare these changes with the effects of a placebo device. MATERIALS AND METHODS: Magnetic resonance (MR) images of 9 dentate apneic subjects with 5 differently designed MASs and without a MAS were obtained. We measured the area of the entire pharynx (velopharynx, oropharynx, hypopharynx) on these MR images and compared the dimensional changes. RESULTS: The dimensional changes triggered by two specific MASs (75% of the maximum mandibular protrusion with 5 mm vertical opening, and 75% of the maximum mandibular protrusion with 10 mm of vertical opening) in the entire pharynx in the sagittal plane were statistically significant compared to the other MASs (p < 0.05). The MAS effecting 75% of the maximum mandibular protrusion and 10 mm of vertical opening created a significant dimensional increase only in the velopharyngeal area among the three pharyngeal sites (p ≤ 0.003). CONCLUSION: While the degree of mandibular protrusion created by the MAS affects the dimensions of the upper airway, the degree of the vertical opening exerts no significant dimensional effect in the sagittal plane in fully dentate apneic patients. The mandibular protrusion effect is comparatively larger in the velopharyngeal region.

Effect of orthodontic brackets and different wires on radiofrequency heating and magnetic field interactions during 3-T MRI.

OBJECTIVES: To evaluate the heating and magnetic field interactions of fixed orthodontic appliances with different wires and ligaments in a 3-T MRI environment and to estimate the safety of these orthodontic materials. METHODS: 40 non-carious extracted human maxillary teeth were embedded in polyvinyl chloride boxes, and orthodontic brackets were bonded. Nickel-titanium and stainless steel arch wires, and elastic and stainless steel ligaments were used to obtain four experimental groups in total. Specimens were evaluated at 3 T for radiofrequency heating and magnetic field interactions. Radiofrequency heating was evaluated by placing specimens in a cylindrical plastic container filled with isotonic solution and measuring changes in temperature after T1 weighted axial sequencing and after completion of all sequences. Translational attraction and torque values of specimens were also evaluated. One-way ANOVA test was used to compare continuous variables of temperature change. Significance was set at p < 0.05. RESULTS: None of the groups exhibited excessive heating (highest temperature change: <3.04 °C), with the maximum increase in temperature observed at the end of the T1 weighted axial sequence. Magnetic field interactions changed depending on the material used. Although the brackets presented minor interactions that would not cause movement in situ, nickel-titanium and stainless steel wires presented great interactions that may pose a risk for the patient. CONCLUSIONS: The temperature changes of the specimens were considered to be within acceptable ranges. With regard to magnetic field interactions, brackets can be considered "MR safe"; however, it would be safe to replace the wires before MRI.

Analysis of 33 pediatric trauma victims in the 1999 Marmara, Turkey earthquake.

BACKGROUND/PURPOSE: The Marmara earthquake, which destroyed more than 150,000 buildings and caused 15,000 deaths and 40,000 casualties, resembled the Hanshin-Awaji earthquake in many respects. Previous reports from similar disasters from several centres have not addressed trauma in the pediatric age group. The aim of this study was to analyze the clinical and laboratory data of pediatric trauma patients referred to a tertiary center after the 1999 Marmara earthquake. METHODS: The medical records of 33 injured children, aged from 14 days to 16 years, were reviewed retrospectively. The time spent buried under rubble, type of injury, treatment given, complications, laboratory data, and development of acute renal failure (ARF) were noted. Patients in whom ARF developed were treated with a standard regimen of fluid replacement, alkalinization, and diuretics. Limbs with crush injuries were managed as conservatively as possible. RESULTS: All except 3 cases were evacuated from under the debris of collapsed buildings after 1 to 110 (mean, 30.04 +/- 6.48) hours. Seventy-eight percent were transported to our center within the first 3 days. Crush injury (CI) was present in 15 cases, and in 10 of them ARF had already developed by admission. Although serum levels of creatinine were elevated (1.2 to 5 mg/dL) in all cases with ARF, hyperkalemia was observed in only 4. The mean serum creatinine kinase (CK) level of cases with crush syndrome (CS) was 6,040 +/- 4,158 U/L. No significant correlations were detected between the development of CS, age, the time spent under the rubble, the time before admission, or the number of crushed extremities. CONCLUSIONS: CI and CS were the most common entities encountered among our pediatric patients after the 1999 Marmara earthquake. The high incidence of ARF indicates the importance of medical management of this age group during rescue. Because neither laboratory data nor clinical findings predicted CS in our patients, we recommend close observation and monitoring of children with CI for the development of ARF.