Three-dimensional reconstruction of enamel thickness and volume in humans and hominoids.

Enamel thickness is an important diagnostic characteristic in Hominoidea. However, the sample size is extremely small, relying upon mostly fractured specimens and a few sectioned specimens, providing an estimate of enamel thickness only. What is needed to fully understand the significance of enamel thickness is a non-destructive technique that is able to obtain the thickness, density, and volume of the dental hard tissues of large samples, thereby providing an accurate means of relating thickness, area, volume, and the pattern of distribution of both enamel and dentin. Investigators have attempted to circumvent this problem by developing a variety of indexes. However, we are still left with subjective descriptions, such as 'thin', 'thick', 'intermediate thick', and 'hyperthick'. The purpose of this investigation was therefore to demonstrate the ability of high-resolution X-ray computed microtomography (HRXCT), as a non-destructive method, to produce, accurately and reliably, contiguous slices revealing the thickness and area of enamel, dentin, and pulp chamber. Using imaging software, three-dimensional reconstructions were produced, which provided volume data for enamel and dentin. Three-dimensional reconstruction of HRXCT images provide, for the first time, the capability of accurately quantifying enamel and dentin thickness, distribution and volume, thereby eliminating the necessity of destructive thin-sectional analysis.

The effect of opening wedge thoracostomy on thoracic insufficiency syndrome associated with fused ribs and congenital scoliosis.

BACKGROUND: Thoracic insufficiency syndrome is the inability of the thorax to support normal respiration or lung growth and is seen in patients who have severe congenital scoliosis with fused ribs. Traditional spinal surgery does not directly address this syndrome. METHODS: Twenty-seven patients with congenital scoliosis associated with fused ribs of the concave hemithorax had an opening wedge thoracostomy with primary longitudinal lengthening with use of a chest-wall distractor known as a vertical, expandable prosthetic titanium rib. Repeat lengthenings of the prosthesis were performed at intervals of four to six months. Radiographs were analyzed with respect to correction of the spinal deformity, as indicated by a change in the Cobb angle, and lateral deviation of the spine, as indicated by the interpedicular line ratio. Spinal growth was assessed by measuring the change in the length of the spine. Correction of the thoracic deformity and thoracic growth were assessed on the basis of the increase in the height of the concave hemithorax compared with the height of the convex hemithorax (the space available for the lung), the increase in the thoracic spinal height, and the increase in the thoracic depth and width. The thoracic deformity in the transverse plane was measured with computed tomography, and the scans were analyzed for spinal rotation, thoracic rotation, and the posterior hemithoracic symmetry ratio. Clinically, the patients were assessed on the basis of the relative heights of the shoulders and of head and thorax compensation. Pulmonary status was evaluated on the basis of the respiratory rate, capillary blood gas levels, and pulmonary function studies. RESULTS: The mean age at the time of the surgery was 3.2 years (range, 0.6 to 12.5 years), and the mean duration of follow-up was 5.7 years. All patients had progressive congenital scoliosis, with a mean increase of 15 degrees /yr before the operation. The scoliosis decreased from a mean of 74 degrees preoperatively to a mean of 49 degrees at the time of the last follow-up. Both the mean interpedicular line ratio and the space available for the lung ratio improved significantly. The height of the thoracic spine increased by a mean of 0.71 cm/yr. At the time of the last follow-up, the mean percentage of the predicted normal vital capacity was 58% for patients younger than two years of age at the time of the surgery, 44% for those older than two years of age (p < 0.001), and 36% for those older than two years of age who had had prior spine surgery. In a group of patients who had sequential testing, all increases in the volume of vital capacity were significant (p < 0.0001), but the changes in the percentages of the predicted normal vital capacity were not. There was a total of fifty-two complications in twenty-two patients, with the most common being asymptomatic proximal migration of the device through the ribs in seven patients. CONCLUSIONS: Opening wedge thoracostomy with use of a chest-wall distractor directly treats segmental hypoplasia of the hemithorax resulting from fused ribs associated with congenital scoliosis. The operation addresses thoracic insufficiency syndrome by lengthening and expanding the constricted hemithorax and allowing growth of the thoracic spine and the rib cage. The procedure corrects most components of chest-wall deformity and indirectly corrects congenital scoliosis, without the need for spine fusion. The technique requires special training and should be performed by a multispecialty team.

The characteristics of thoracic insufficiency syndrome associated with fused ribs and congenital scoliosis.

1. Thoracic insufficiency syndrome is the inability of the thorax to support normal respiration or lung growth. 2. The rare condition of fused ribs and congenital scoliosis may result in a three-dimensional thoracic deformity with adverse effects on thoracic growth and function with development of thoracic insufficiency syndrome. 3. The normal thorax is defined by two characteristics: normal, stable volume and the ability to change that volume. Volume depends on the width and depth of the rib cage, and the thoracic spine provides height. The ability to change volume, termed thoracic function, is provided by the diaphragm and the secondary muscles of respiration. 4. On radiographs, the loss of the vertical height of the lung of the concave, restricted hemithorax is defined by the percentage of space available for the lung. 5. Spine rotation causes a windswept thorax, with both restriction of the volume of the convex hemithorax and restriction of the motion of the involved ribs. 6. Constrictive three-dimensional deformity of the thorax may cause extrinsic, restrictive lung disease. 7. Progressive thoracic insufficiency syndrome is diagnosed on the basis of clinical signs of respiratory insufficiency, loss of chest wall mobility as demonstrated by the thumb excursion test, worsening indices of three-dimensional thoracic deformity on radiographs and computed tomography scans, or a relative decline in percent predicted vital capacity due to thoracic "failure to thrive," as demonstrated by pulmonary function tests. 8. Treatment of progressive thoracic insufficiency syndrome should provide an acute increase in the thoracic volume with stabilization of any flail chest-wall defects and maintain these improvements as the patient grows, without the need for spine fusion.

Reporting of child abuse: a follow-up survey of Texas dentists.

PURPOSE: Child abuse is a disturbingly common finding in society today. There have been substantial and significant increases in the incidence of child abuse since the last national incidence study was conducted in 1986. Kassebaum first reported the under-reporting of child abuse by Texas dental professionals in a survey in 1986. The objective of the current study was twofold: (1) assess the level of knowledge and attitudes among dental professionals on the important issue of child abuse; (2) evaluate and compare the results of the current study with a similar survey conducted in 1986. METHODS: A 24-question survey similar in format and content to the 1986 questionnaire was mailed to 1,046 Texas dentists, randomly selected from a membership roster provided by the Texas Dental Association. Both general dentists and selected specialists were included in the study group. The questionnaire consisted of multiple-choice and dichotomous yes/no questions. RESULTS: There were 383 responses to the questionnaire, yielding a response rate of 38%. The majority (N=289) of the respondents were general dentists. In answering questions about suspected and reported cases of child abuse, nearly 50% of the responding dentists reported they had suspected at least 1 case of child abuse. In the 1986 study, only 36% of the responding dentists reported they had suspected at least 1 case of child abuse. Between 1986 and 2001, the survey has shown that the percentage of dentists who reported at least 1 case to authorities slightly increased from 19% in 1986 to 25% in 2001, but the ratio of suspected to reported cases had not changed since 1986. CONCLUSIONS: Although the composite percentage of suspecting and reporting cases of child abuse from this survey is higher than the percentage demonstrated in 1986 study, there was no significant change in the relative ratio of reported cases to suspected cases in both surveys. This indicates that under-reporting of child abuse cases is still a significant problem in the dental profession in Texas.

Maxillary sinus septa: a 3-dimensional computerized tomographic scan analysis.

PURPOSE: The purpose of this study was to determine the prevalence, size, location, and morphology of maxillary sinus septa in dentate, partially dentate, and edentulous maxillae. MATERIALS AND METHODS: Data from 312 sinuses were analyzed from reformatted computerized tomograms utilizing SIM/Plant software. The sample consisted of 156 patients (106 women and 50 men, with ages ranging between 24 and 86 years and a mean age of 55.4 years) who were being treatment-planned to receive implant-supported restorations. RESULTS: A total of 75 septa were found in 312 maxillary sinuses (24%), which corresponded to 32.7% of the patients (51 of 156). Completely edentulous patients presented with 33.3% of the total septa, while 66.7% of the septa were identified in partially edentulous patients. Analysis of the anatomic location of the septa within the sinus revealed that 18 (24.0%) septa were located in the anterior region, 31 (41.0%) were in the middle, and 26 (35.0%) were in the posterior region. Measurements of height of the septa varied among different areas. The lateral area ranged from 0 to 15.7 mm (with a mean of 3.54 +/- 3.35 mm), the middle area ranged from 0 to 17.3 mm (with a mean of 5.89 +/- 3.14 mm), and the medial area ranged from 0 to 20.6 mm (with a mean of 7.59 +/- 3.76 mm). A total of 20 septa (26.7%) were located in the immediate apical region of teeth. The remaining 55 septa (73.3%) were related to edentulous areas. DISCUSSION: Septa may arise in any of the 3 regions of the maxillary sinus irrespective of the degree of dentulism or edentulism present. CONCLUSION: To avoid unnecessary complications during sinus augmentation procedures, adequate and timely identification of the anatomic structures inherent to the maxillary sinus are required.