Validation of the Chick Embryotoxicity Screening Test (CHEST). A comparative study

The purpose of the present study was to compare the effects of Gjessing's canine retraction arch with a sectional arch including a reverse closing loop, which are both used for canine retraction in extraction cases. Our study involved both the maxilla and the mandible independently. After upper first premolar extractions and levelling of the teeth with 0.018-inch slot standard Edgewise appliances on 12 subjects, with a mean age of 15 years, the right maxillary canines were retracted by 0.016 x 0.022-inch sectional arches including a reverse closing loop, for a mean period of 7.75 months whereas the left maxillary canines were retracted by 0.016 x 0.022-inch Gjessing retraction arches for a mean period of 6.25 months. Following lower first premolar extractions and levelling of the teeth in eight subjects with a mean age of 13 years 7 months, the right mandibular canines were retracted by 0.016 x 0.022-inch sectional arches with reverse closing loop for a mean period of 7.75 months and the left mandibular canines were retracted by 0.016 x 0.022-inch Gjessing arches for a mean period of 6 months. The present study was carried out on 40 lateral cephalometric films of 20 subjects taken prior to and at the end of canine retraction. The differences between the mean changes of the sectional arch including reverse closing loop and Gjessing retraction arch groups were found to be statistically significant for the amount of upper canine crown retraction, mesial movement of upper first molar crown and duration and rate of upper canine distal movement.(ABSTRACT TRUNCATED AT 250 WORDS)     

Long-term effects of the Herbst appliance on the dental arches and arch relationships: a biometric study

The purpose of this study was to evaluate biometrically the treatment and post-treatment effects of the Herbst appliance on the dental arches and arch relationships. The sample consisted of 53 Class II, division 1 malocclusion patients (33 boys and 20 girls) treated with the Herbst appliance. The mean age of the patients before treatment was 12.5 years (SD = 1.2 years). Dental casts were analysed before treatment, after treatment, 6 months post-treatment and at the end of the growth period (5-10 years post-treatment). The following variables were assessed: sagittal molar and canine relationships, overjet, overbite, maxillary and mandibular arch perimeters, and inter-molar and inter-canine dental arch widths. During treatment, the overjet, overbite, and sagittal molar relationship were overcorrected in most of the cases, while the sagittal canine relationship was normalized. The maxillary and mandibular arch perimeters increased during treatment, as did dental arch widths (molar and canine). In the long-term (mean = 6.7 years after treatment), Herbst appliance treatment resulted in a normal or over-corrected sagittal molar relationship in 79 per cent and a normal canine relationship in 68 per cent of the cases. Eighty-three per cent of the subjects had an overjet of 4.5 mm or less. In the long-term, the arch perimeters seemed to follow a normal dental development pattern. The increase of the upper molar and canine dental arch widths during treatment remained virtually stable whilst the lower intermolar arch widths seemed unaffected by treatment.     

A study of anterior guidance

PURPOSE: This study focuses on the curvature and inclination of the lingual surfaces of the maxillary anterior teeth from the transition point on the cingulum to the incisal edge. MATERIALS AND METHODS: On 32 sets of mounted casts, 768 measurements were made of the curvature of the lingual surfaces utilizing radius gauges. The inclination of the lingual surface relative to the occlusal plane was recorded. The relationship of the incisal edge of the mandibular teeth to the transition point on the cingulum of the maxillary teeth was determined. Centric occlusion contact was noted on each tooth. RESULTS: Significant differences were found between the measured areas of any one tooth and between the types of teeth. The average radius ranged from 20.5 mm on the mesial ridge of the canine to 5.3 mm in the fossa of the central. The average inclination of the lingual surfaces was 46 degrees. In centric occlusion, 97% of the canines and 59% of the centrals and laterals were in contact with the opposing teeth. These contacts occurred 2.8 mm incisal to the transition point. The centrals contracted two opposing teeth (45%), and canines contacted one opposing tooth (53%). CONCLUSIONS: The function and curvature of the incisor teeth vary considerably from those of the canines. Overcontouring the lingual surfaces of the maxillary incisors to gain contact is not normal and may be detrimental.     

Extraoral tooth eruption and transposition of teeth following trauma

A six-year-old boy presented with extraoral eruption of a mandibular permanent canine and a loosely attached lateral incisor in the labial vestibule, 3 months following trauma to the chin. The trauma not only caused displacement of the permanent tooth buds, but also resulted in transposition of the lateral incisor and canine with subsequent ectopic eruption. The case is presented to demonstrate one of the infrequent complications of trauma involving the unerupted tooth buds of permanent teeth and its unusual clinical presentation.     

Hypodontia of primary and permanent teeth in a sample of Saudi children

Hypodontia, congenitally missing teeth is more common in permanent than primary dentition. The present investigation reports the prevalence and pattern of hypodontia in the primary and permanent dentitions, excluding third molars in a sample of Saudi children. The sample consists of 1,300 children, aged 5 to 10 years of age. Clinical and radiographic examinations were performed. The prevalence of children with hypodontia was found to be 2.6 percent. The mandibular second premolar was the tooth most frequently absent and account for 45 percent of the total missing teeth. In primary dentition, the maxillary lateral incisor was the tooth most frequently absent (9%). A peg-shaped permanent maxillary lateral incisor was present in 0.7 percent of the sample. Congenitally missing teeth were almost equally distributed between maxillary (52%) and mandibular (48%) arches.     

The impacted maxillary canine. Further observations on aetiology, radiographic localization, prevention/interception of impaction, and when to suspect impaction

Adjacent anomalous or missing maxillary lateral incisors have been implicated in the aetiology of palatally displaced canines by not providing proper guidance to the canine during its eruption. However, a recent review of the literature suggests that the aetiology of palatally displaced canines is genetic in origin. The aetiology of labially impacted canines differs, being due to inadequate arch space. Vertex occlusal radiographs have been recommended for localization but have limitations, and a case is illustrated where this radiograph is deceptive. The prevention/interception of a palatally displaced canine by the extraction of the deciduous canine is best carried out as early as the displacement is detected, mostly soon after 10 years of age. Usually, prevention/interception will avoid the surgical and orthodontic treatment needed to align a palatally impacted canine and may help prevent resorption of the adjacent incisor root. Suspicions that an impaction could occur or has occurred arise a) before the age of 10 years if there is a familial history and/or the maxillary lateral incisors are anomalous or missing; b) after the age of 10 years if there is asymmetry in palpation or a pronounced difference in eruption of canines between the left and right side; or the canines cannot be palpated and occlusal development is advanced; or, the lateral incisor is proclined and tipped distally; and, on a panoramic radiograph of the late mixed dentition if the incisal up of the canine overlaps the root of the lateral incisor.     

Ketorolac (Toradol) as an analgesic in swine following transluminal coronary angioplasty

The arch forms of 38 cases (53 nonextraction and 23 extraction arches) in which expansion, while maintaining arch form, was the objective of the practitioner, were analyzed before treatment, after treatment, and an average of 6 to 8 years after retention. The cubic spline was used to fit a curve representing arch form. By superimposing the spline curves, changes in arch form were analyzed with the variables rebound change (RC), rebound index (RI), rebound number (RN), and stability number (SN). Traditional linear intraarch dimensions were also analyzed. Analysis of variance was used to determine differences between the maxillary and mandibular arches and between the extraction and nonextraction cases. Pearson correlation coefficients between spline variables and arch width variables were also computed. There was significantly more expansion in the maxillary arch than the mandibular arch during treatment, irrespective of extraction or nonextraction strategies. In the nonextraction cases, a greater amount of net expansion was achieved for all dimensions for the maxillary arch as compared with the mandibular arch. Overall, a relatively high stability in arch form was found. The findings suggest that stability may not be related to the amount of change produced during treatment. Significant expansion can be gained throughout the premolar regions and may be expected to be stable. The order of greatest net arch width gained was for the second premolars followed by first premolars, molars, and then the canines. The intercanine widths for both arches decreased toward pretreatment values, but were more stable in the maxillary arch in nonextraction cases. The cubic spline permits measurement of change in arch form both during treatment and retention periods.     

Concomitant hypohyperdontia: simultaneous occurrence of a mesiodens and agenesis of a maxillary lateral incisor

A 13-year-old boy appeared for evaluation with a missing maxillary left lateral incisor. He also had an abnormally shaped tooth in the midline between his maxillary central incisors. This mesiodens had an incompletely developed root. The unusual association of these 2 anomalies is discussed as a possible transposition of the lateral incisor to the mesiodens position.     

Dynamics of the drug scene in Switzerland 1977-1990

A mathematical model of anterior inter-arch relations was described in a previous article. This model is modified and manipulated and, using hypothetical dental measurements, results are generated and presented. The present work continues the two-dimensional examination of anterior dental relations in the first article, the emphasis remaining on incisor and canine overjet. Other authors have started by observing ideal occlusions, then have worked backwards to gain ratios of preferred maxillary to mandibular teeth widths; this restricts their studies to Class I occlusions with complete anterior dentitions and similar anterior form of both arches. This paper has no premise of normal or initial ratios. Incorporation of multiple factors allows forming and testing of hypotheses of anterior dental relations. Many factors influence anterior dental relations in varying degrees. Some dental measurement changes examined here are: the sum of teeth widths in each arch; spacing; crowding; angle of the arc of each arch and the antero-posterior buccal relation. Summary tables are presented to aid the prediction of the direction of inter-arch response to change in a dental measurement. Some inferences are discussed and are presented as a series of principles considered valid for this model. The principles may warrant testing with other arch form models.     

Long-term assessment of early alveolar bone grafts using three-dimensional computer-assisted tomography: a pilot study

Fifteen patients with complete unilateral cleft lip and palate who had primary alveolar bone grafting were studied with computer-assisted tomography at a mean age of 12 years. Keeping the maxillary alveolar crest parallel to the plane of the scan, 1.5-mm cuts of the maxilla were made from the infraorbital rim to the gingival third of the crowns of the teeth. A single operator reformatted the data into three-dimensional images using the Maxiview 3200 computer workstation. This allowed examination of the position, size, and spatial relationship of the grafted area and quantification of the amount of bone coverage of root surface and bone height of the alveolus in or adjacent to the graft site. Ten patients showed a lateral incisor in the line of the cleft. The average bony coverage of these tooth roots was 76.5 percent. In the five patients in whom there was lateral incisor agenesis, the canine root had average bony coverage of 82.6 percent. The average height of bone at the lateral incisor was 8.7 mm; at the canine, 14.1 mm. In two patients in whom there was only 42 percent tooth root coverage, the teeth were still viable, stable, and without mobility. Computed tomographic (CT) scans of the 15 patients demonstrated good graft survival with adequate volume. The functional and aesthetic status of the dentition in the area of the cleft also was demonstrated.     

Dynamic relationships of the mandibular anterior segment

The hyperbolic cosine function is shown to be an accurate representation of the form of the mandibular anterior teeth from the canine/first premolar contact on one side around the perimeter to the opposite side (r = 0.951). On the basis of this mathematical function, the changes in canine width, anterior segment depth, arch perimeter, and their related incisor angular alterations are forecastable. This knowledge will allow the clinician to predict the effects on various aspects of the anterior segment arch form as one or more of these variables are altered without resorting to trial and error or performing a wax-up. For example, the clinician can predict the change in the anterior segment arch depth and incisor angulation that would occur with alterations in canine width.     

Biomechanical and esthetic considerations for maxillary anterior overdenture abutment selection

Maxillary canine teeth traditionally have been selected as overdenture abutments. Undesirable aspects associated with the use of maxillary canines as overdenture abutments are described. The use of maxillary lateral incisors as overdenture abutments offers vertical support to the prosthesis, favorable stress distribution, improved esthetics, and preservation of the premaxilla.     

A dosimetric analysis of behavioral effects of acute toluene exposure in rats and humans

Contradictory findings from studies on pretreatment malalignment as a risk factor for relapse of maxillary incisor alignment may be due to inappropriate sample selection and measurement technique. In an attempt to clarify the issue, 745 sets of study models made before (T1) and after (T2) orthodontic treatment and at long-term out of retention (T3) were screened. On the basis of the configuration of the maxillary anterior teeth on the T3 study models, three groups were established: one with significant spacing (group 1, n = 30); one with significant irregularity (group 2, n = 49); and one with perfect alignment (group 3, n = 28). The occlusal surfaces of the 321 maxillary study models at T1, T2, and T3 were photocopied and the tooth anatomic contact points digitized. An algorithm was used to fit the dental arch to the digitized points. Amount of incisor rotation and anatomic contact point displacement of the maxillary anterior teeth relative to the dental arch were computer generated. Interdental spaces in the maxillary anterior segment, as well as overjet and overbite, were measured manually. Nonstructural data were collected from the charts. Logistic regression analyses revealed that irregularity was associated with greater anatomic contact displacement and with greater incisor rotation both at T1 and T2 (P < 0.01). Similar analyses also revealed that spacing was associated with greater interdental spaces at T1 and T2 (P < 0.01). Correlation analyses revealed that the pattern of pretreatment rotational displacement has a strong tendency to repeat itself after retention (P < 0.001), as opposed to the pattern of contact point displacement and interdental spacing.     

Influence of the arterial blood pressure and nonhemodynamic factors on regional arterial wall properties in moderate essential hypertension

OBJECTIVES: The technique of resin-bonded bridgework is a well-accepted clinical technique to replace missing teeth. This study assesses the clinical performance of cantilevered resin-bonded bridgework provided in a university teaching hospital environment. METHODS: One-hundred and twelve patients who had a total of 142 cantilevered bridges were either examined or completed a questionnaire regarding their bridgework. The following data were recorded for each resin-bonded bridge: gender of patient, age at bridge cementation, date of initial cementation, tooth replaced, abutment(s) involved, and grade of clinician responsible for the provision of the bridge. Details of the incidence of debonding with date(s) and the subsequent treatment in relation to the debonded resin-bonded bridge were recorded. The subjects examined indicated their degree of satisfaction with their bridgework on a visual analogue scale. RESULTS: There were 112 patients with a total of 142 bridges, 116 (82%) maxillary and 26 (18%) mandibular. The mean length of clinical service was 36.2 months (s.d. 17.2 months). Only single pontics were included in the bridges, with almost half (49%) replacing a lateral incisor. Of the cantilever resin-bonded bridges studied, 88% remained bonded over the period of the study. A success rate of 94% is reported. CONCLUSION: This study confirms the clinical success of cantilever resin-bonded bridges particularly in the replacement of maxillary lateral incisors, maxillary premolar and permanent mandibular teeth.     

Posttreatment changes in male and female patients: a comparative study

The purpose of this study was to determine whether the posttreatment changes in patients with Class II, Division 1 malocclusions who were treated with either extraction or nonextraction express similar trends in the male and female patients. The material for this investigation was obtained from the records available in the Graduate Orthodontic Clinic at the University of Iowa. Ninety-one patients were treated for their Class II, Division 1 malocclusions, 44 subjects (21 males and 23 females) had four first premolar extractions and 47 subjects (20 males and 27 females) were treated with nonextraction. Matched normal subjects included 20 male and 15 female subjects for whom complete sets of data were available for the period of this study. None of these subjects had undergone orthodontic therapy. Thirty-nine cephalometric anteroposterior and vertical skeletal, dental, and soft tissue linear and angular measurements were derived. Twenty-four dental arch parameters were evaluated and included: overbite, overjet, maxillary and mandibular arch lengths, and arch widths, as well as tooth size-arch length discrepancies. Student t tests were used to compare male and female subjects for the following parameters: (1) absolute dimensions recorded before treatment, after treatment, and at retention; (2) the incremental changes between the various stages; (3) the relative posttreatment changes. The level of significance was predetermined at p < 0.05. From the current findings the following can be concluded: (1) There were significant differences in the size as well as the incremental changes of the various cephalometric dentofacial parameters between normal male and female subjects. (2) There were significant differences in the absolute posttreatment cephalometric changes between male and female subjects, particularly in linear dimensions. Similar, but less frequent, findings were observed in the relative posttreatment changes. (3) Significant differences in the posttreatment dental arch changes between male and female subjects were the least frequent. (4) Male and female subjects expressed similar statistical trends in the direction of posttreatment changes. Therefore clinicians should not expect to observe significant differences in the posttreatment trends on the basis of the gender of the patient. On the other hand, the changes in linear dimensions are larger in male than female subjects. Therefore, for a more accurate interpretation of growth and/or treatment changes, it is advisable to independently analyze data on male and female subjects.     

Maturation alters the contractile role of calcium in ovine basilar arteries

OBJECTIVE: To investigate the distribution patterns of primary and permanent teeth in the cleft area and the numerical variation in teeth in unilateral complete cleft lip and palate (UCLP) patients. DESIGN: A survey of the dentition in UCLP patients. SETTING: Craniofacial Center, Chang Gung Memorial Hospital, Taipei, Taiwan. PATIENTS: 137 UCLP patients who met the following criteria: (1) have had at least one panoramic film taken, (2) the first panoramic film illustrates either primary or early mixed dentition. Evaluation of both permanent and primary dentition was available in 91 cases. MAIN OUTCOME MEASURES: Two evaluators performed independent evaluations of number and distribution of teeth in UCLP patients. The hypothesis that there are two odontogenic origins for maxillary lateral incisors was proposed to explain the occurrence of distribution patterns of dentition in the cleft area and to explain differences between primary and permanent dentition in UCLP patients. RESULTS: Four distribution patterns in the cleft area were identified in both the primary and the permanent dentition. In the primary dentition, placement of the lateral incisor distal to the alveolar cleft was the predominant pattern (pattern y, 82.4%), followed by absence of the cleft side maxillary lateral incisor (pattern ab, 9.9%), presence of one tooth on each side of the alveolar cleft (pattern xy, 5.5%), and placement of the lateral incisor mesial to the alveolar cleft (pattern x, 2.2%). In the permanent dentition, the most common pattern was the absence of the maxillary lateral incisor on the cleft side (pattern AB, 51.8%), followed by lateral incisor placement distal to the alveolar cleft (pattern Y, 46%), lateral incisor placement mesial to the alveolar cleft (pattern X, 1.5%) and the presence of one tooth on each side of the alveolar cleft (pattern XY, 0.7%). The discrepancy between the distribution patterns of primary dentition and permanent dentition successors is 57.1%. Variations in tooth number in both primary and permanent dentition of UCLP patients occurred most often in the cleft area. Abnormalities in the number of teeth (hypodontia or hyperdontia) outside the cleft area were more common in the permanent dentition than in the primary dentition (24.1% versus 4.4%). CONCLUSIONS: Four distribution patterns in the cleft area were identified in both sets of dentition. Our findings of distribution patterns in UCLP patients support the hypothesis that there may be two odontogenic origins for maxillary lateral incisors. Clinicians involved in managing the dentition of UCLP patients should consider the high frequency of numerical variation both in and outside the cleft area before starting dental treatment.     

Prevalence of developmental enamel defects and dental caries in rural pre-school Thai children

The prevalence of developmental enamel defects and dental caries was assessed in 344 Karen children aged 1-4 years who were chronically (70 per cent) and acutely malnourished (9.3 per cent) The teeth were cleaned with gauze to facilitate detection of hypoplastic lesions on labial surfaces of maxillary incisors. At least one tooth with defective enamel was seen in 31.9 per cent of children, while enamel hypoplasia was present in 22.7 per cent of children. Enamel defects were found in 21.2 per cent of teeth, with hypoplasia and opacities occurring in 14.6 and 6.6 per cent of teeth, respectively. Gender did not alter the prevalence of defects. The upper central incisors were affected more than lateral incisors. The prevalence of dental caries was 31.9 per cent with a mean dt of 1.1. The prevalence of caries associated with enamel hypoplasia was significantly greater than that associated with opacities and sound enamel (P < 0.0005).     

Malocclusion traits and symptoms and signs of temporomandibular disorders in children with severe malocclusion

The present study reports the prevalence of the various traits of malocclusion, as well as the occurrence of associations between malocclusion, and symptoms and signs of temporomandibular disorders (TMD) in children selected for orthodontic treatment by the new Danish procedure for screening the child population for severe malocclusions entailing health risks. The sample comprised 104 children (56 F, 48 M) aged 7-13. Malocclusion traits were recorded at the time of selection, symptoms and signs of TMD were recorded at recall. The most prevalent malocclusion traits were distal molar occlusion (Angle Class II; 72 per cent), crowding (57 per cent), extreme maxillary overjet (37 per cent) and deep bite (31 per cent). Agenesis or peg-shaped lateral teeth were observed in 14 per cent of the children. The most prevalent symptom of TMD was weekly headache (27 per cent); the most prevalent signs of TMD were tenderness in the anterior temporal, occipital, trapezius, and superficial and profound masseter muscles (39-34 per cent). Seven per cent of the children were referred for TMD treatment. The Danish TMD screening procedure was positive in 26 per cent, while 20 per cent had severe symptoms (Aill), and 30 per cent had moderate signs (Dill) according to Helkimo (1974). Symptoms and signs of TMD were significantly associated with distal molar occlusion, extreme maxillary overjet, open bite, unilateral crossbite, midline displacement, and errors of tooth formation. The analysis suggests that there is a higher risk of children with severe malocclusions developing TMD. Errors of tooth formation in the form of agenesis or peg-shaped lateral teeth showed the largest number of associations with symptoms and signs of TMD; these associations have not previously been reported in the literature.     

Examination of the degree of agreement among dental findings used for personal identification (report 5)--canonical correlation between dental findings on dental charts and those on radiographs

Findings obtained from dental charts and from radiograph taken one year later for the same individuals were examined and classified according to different criteria. Similarities between the two sources investigated by the canonical correlation method. The results obtained were as follows: 1. The correlation coefficient and the squared multiple correlations (R2) were calculated. Consequently, high similarities were seen between the two sources for the mandibular anterior teeth [sequence: see text], maxillary incisor teeth [sequence: see text], mandibular and maxillary first premolar teeth [sequence: see text], and the corresponding teeth of the same jaws. 2. Three roots showed high elucidative values by the canonical correlation method. The first root was understood to be the mandibular incisor factor, the second the maxillary incisor factor, and the third the first premolar factor. This seemed to indicate, that the similarities between the two sources in these regions were very high. 3. A study of the similarities between the two sources was done based on the individual scores of canonical variable loadings calculated in this analysis. High similarities were seen at [sequence: see text] in category 1 (intact & C1) for chart findings and category 1'(intact, C1-C3 & resin filling) for radiographic findings: at [sequence: see text] in category 2 (C2-C4, inlay & filling of repair) for chart findings and category 3'(stump of tooth) for radiographic findings; and at [sequence: see text] in category 3 (complete crown, jacket crown & post crown) for chart findings and category 3'(stump of tooth) for radiographic findings. 4. The present results suggest that if proper case in taken, one set of information can serve as a substitute for the other. In personal identification, higher efficiency may be achieved if this is borne in mind.