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.     

Sex determination with a discriminant function analysis of deciduous teeth size in plaster models

Plaster models of the teeth of 3-year-old Japanese children (96 males, 98 females) were used to record the crown length, crown width and crown thickness of 5 maxillary and 5 mandibular deciduous teeth (30 measurement values). These measurements were used to devise a number of sex determination formulae. A sex-determination formula using all 30 values was calculated. Furthermore, a number of practical formulae were derived from only the crown width and crown thickness values because the deciduous teeth wear in 4 years and older children rapidly progress, making the crown length measurement unreliable. These formulae were calculated for the maxillary teeth alone and mandibular teeth alone. The formulae based on only the crown width or thickness were also calculated for both maxillary and the mandibular teeth. A step-wise discriminant analysis was then used to ascertain the most reliable measurements and a practical formula subsequently devised. The results obtained were as follows: 1. The mean value for each measurement was greater in males than in females. 2. Significant differences in the values recorded were seen in 28 out of the 30 measurements taken. The measurement items not exhibiting these significant differences were the crown width of the maxillary lateral incisor and the crown thickness of the mandibular second molar. 3. The accuracy rates for the sex-determination analysis and the step-wise sex determination analysis calculated using all 30 values were 78.6% and 75.7%, respectively. 4. The accuracy ranges for the modified sex-determination formulae and the associated step-wise sex determination analyses were 70.6-78.4% and 67.0-76.8%, respectively.     

Sexual transmission of GB virus C/hepatitis G virus

Tooth transposition is a positional interchange of two adjacent teeth. The most commonly transposed tooth is the permanent canine with either the first premolar or lateral incisor. The records of 54 subjects with transposed canines, both maxillary and mandibular, were collected. Pretreatment study models of these subjects were matched with a similar number of models from unaffected individuals. Bucco-lingual and mesio-distal tooth widths, arch depth and arch width were measured on each model. Thirty-four subjects (63 per cent) were female. Thirty-seven (68.5 per cent) of the cases involved the maxillary arch and thirty-three (89.2 per cent) of these upper arch transpositions were of the canine and first premolar. In cases involving the lower arch the canine was invariably transposed with the lateral incisor. Peg-shaped lateral incisors, supernumerary and/or congenitally absent teeth occurred in 19 subjects. There were some small, but significant differences in the dimensions of some teeth, however there were no statistically significant differences in arch depths, arch widths and most tooth dimensions in subjects with and without transposed canines. These factors do not appear to be related to the development of canine transposition.     

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.     

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)     

Human leucocyte antigens in pregnant women with pre-eclampsia associated with intrauterine growth retardation and in normal controls

Prenatal exposure to anticonvulsant medication has been shown to cause craniofacial dysmorphology, prenatal growth retardation, hypoplastic nails and phalanges, and visceral abnormalities. In this study we examined maxillary and mandibular stone dental casts (45) and panoramic radiographs (39) from 45 individuals with ages 4.5 to 22.0 years for changes in mesiodistal crown size of deciduous and permanent teeth, and the presence of dental anomalies. These individuals had been exposed prenatally to antiepileptic drugs (AEDs). Mesiodistal crown diameters were measured from the dental casts and converted into standard scores (Z), using published normative data from the University of Michigan Longitudinal Craniofacial Growth Series. A significant increase in mesiodistal crown dimensions of the posterior maxillary teeth was observed, specifically in primary molars and their permanent premolar successors, as well as permanent molars. Changes in tooth size were more common in females than in males. Dental maturity, assessed using the panoramic radiographs, was equal to chronologic age. An increased frequency of hypodontia was the only notable dental anomaly.     

Effect of restored and unrestored non-carious cervical lesions on the fracture resistance of previously restored maxillary premolar teeth

OBJECTIVES: The effect of non-carious cervical lesions (NCCL) on tooth fracture resistance has not previously been investigated. The aims of this in vitro study were to examine the fracture resistance of a group of extracted maxillary premolar teeth with mesio-occlusal-distal (MOD) restorations of amalgam, and restored or unrestored simulated NCCL. METHOD: Forty sound maxillary, premolar teeth were divided at random into four groups, each of 10 teeth, which were fixed crown uppermost and long axis vertical in stainless steel moulds. Groups 1,2,3 and 4 were prepared with standardized parallel-sided MOD cavities, then restored with amalgam. Groups 1, 2 and 3 were further prepared with standardized NCCL. The NCCL in Group 1 were restored using a resin-modified polyalkenoate (glass-ionomer) cement, and the NCCL in Group 2 were restored with an adhesive composite resin system. The NCCL in Group 3 were left unrestored. The specimens were loaded compressively at 1 mm min-1 using a universal testing machine. RESULTS: Mean fracture loads (KN) of 1.08, 1.03, 0.98 and 1.14, respectively, were recorded for Groups 1, 2, 3 and 4. Two-way ANOVA and Scheffe's Multiple Range Test showed no statistically significant difference between the groups. CONCLUSIONS: It is concluded that the presence of a standardized NCCL in an extracted maxillary premolar tooth does not reduce the fracture resistance of the tooth when loaded compressively at 1 mm min-1. The restoration of NCCL with the materials tested did not result in an increase in the fracture resistance of the previously restored premolar teeth, when loaded compressively at 1 mm min-1.     

Prognosis of lymphogranulomatosis in children with mediastinal damage

Patients are conscious of esthetics and demand natural-appearing dentures. If an undersized mandibular first premolar is used in the denture arrangement, the result may not be esthetically pleasing. This article will show the dental technician how denture arrangements for a Class II jaw relationship can become simplified, more predictable and less frustrating by positioning the mandibular first molar in a distal occlusion, relative to the maxillary first molar. This technique uses zero degree teeth.     

Decisions about prostate cancer screening in managed care

The primary object of this research project was to establish the amount of incisor retraction to be expected during full fixed mechanotherapy and to generate regression models that could provide more accurate prediction of each of the three most popular combinations of symmetrical premolar extractions, where extraoral anchorage would not be used. Pretreatment and posttreatment records of 73 cases that had their four first premolars extracted (group 44), 74 cases with four second premolar extractions (group 55), and 59 cases with upper first and lower second premolar extractions (group 45) were selected. All these cases were treated by one orthodontist, who used the same edgewise technique throughout. The results indicate that, on average, maxillary retraction in relation to the facial plane (N Po) differed only slightly between group 55 (mean 4.2 +/- 2.4 mm) and group 44 (mean 4.7 +/- 2.3 mm), with relatively more retraction for group 45 (mean 6.6 +/- 2.5 mm; p < 0.05). In contrast, the mandibular incisors were retracted slightly more in group 44 than in the other two groups (p < 0.05). The regression models that were developed could be useful as an additional tool to assist the practitioner in the selection of which teeth to extract for a particular case.     

Novel pyrimidinediones and thiazolidinones as anti depressants

2-Mercapto-5-[4'-methoxy phenyl thiourea]-1,3,4-thiadiazole (2a-c) prepared by the condensation of 2-amino-5-mercapto-1,3,4-thiadiazole (1) with substituted phenyl isothiocyanates. Further on cyclisation with malonic acid in the presence of acetyl chloride gave the corresponding 2-mercapto-5-[3-(4-methoxy phenyl)-2-thioxo-2-5-dihydro-4, 6-pyrimidionoyl]-1,3,4-thiadiazole (3a-c) [sequence: see text]. This on further reaction with substituted aryl aldehydes in presence of zinc chloride gave 2-mercapto-5-[3-(4'-methoxy phenyl)-2'-thioxo-2',5'-dihydro-4',6' -pyrimidionoyl 5'-phenyl carboxaldehyde]-1,3,4- thiadiazole (4a-g) [sequence: see text]. The compounds were screened for antidepressant activity and compared with antidepressant (imipramine).     

Oral findings in a group of newborn Swedish children

Oral examinations were performed of 1021 newborn Swedish children, of whom 101 were re-examined after 2-3 or 4-5 months. The most common findings, registered in 74.9% of the children, were of oral mucosal cysts situated either palatally or on the alveolar ridges. The majority of the palatal cysts disappeared shortly after birth, and some alveolar cysts appeared after birth. Ankyloglossia was found in 2.5% of the children, and Fordyce spots in 1.0%. No natal teeth were found. The upper labial frenum was attached to the crest of the alveolar ridge in 76.7% of the children, palatally in 16.7% and buccally in 6.7%. The relationship of the alveolar ridges was recorded: the anterior segment of the mandibular ridge was distal to the maxillary in 99% of cases, and, posteriorly, the mandibular ridges were lingual to the maxillary in 97.6%. An open bite was found in 39.8% of the children.     

A twin study of dental dimension. II. Independent genetic determinants

To demonstrate the presence of independent genetic determinants of multiple correlated tooth dimensions from twin data, a multivariate analysis was performed on the covariance matrices of monozygotic and dizygotic within-pair differences for mesiodistal and buccolingual dimensions of 28 teeth of the secondary dentition. The results provided strong evidences that the correlation among tooth dimensions is primarily genetic in origin, probably attributable to the pleiotropic action of either independent genes or groups of genes. Among the genetic factors that were identified, one appeared to affect the maxillary teeth in general while a second influenced primarily the anterior mandibular teeth. There was a striking tendency for homologous measurements on the right and left sides to be associated with the same genetic factor. In contrast, genetic determination of the maxillary and mandibular dentition seemed to be independent of each other, and a wider range of genetic factors were found to influence the mandibular than the maxillary teeth, suggesting that a differential degree of evolutionary stability may have been achieved in the teeth of the two jaws.     

Monitoring of WT-1 gene expression in peripheral blood of patients with acute leukemia by semiquantitative RT-PCR; possible marker for detection of minimal residual leukemia

The effect of implanting autogenous and xenogenous (Bio-Oss) bone transplants into metabolically active sites within beagle dog mandibles during permanent premolar tooth eruption was examined. Ten 14-week-old beagles were used. Before commencing the radiographic experiments, metal bone markers were placed in the caudal margin of the mandible at the age of 10 weeks. The deciduous first and third molar teeth were extracted and their sockets over the permanent second and fourth premolars were implanted with autogenous particulate enchondral iliac crest bone, autogenous particulate membraneous mandibular body bone, xenogenous bovine anorganic bone mineral spongiosa granules (1-2mm3) (Bio-Oss, Geistlich Pharma, Switzerland) of left empty. The third premolar served as control site. Standardized oblique lateral radiographs were taken once a week. A number of coordinates of defined points and structures were determined by means of a coordinate digitizing system. Animals were killed 4, 10 and 16 weeks after bone transplantation for histological examination of the transplantation sites. All premolars showed no delay in eruption or disruption of crown and root development. On histology, the Bio-Oss particles were not resorbed or integrated in the alveolar bone but were pushed forward into the gingiva. We have demonstrated that there is on difference in the eruption curve of the permanent premolars in the four groups (ANOVA P > 0.5) and that bone transplantation has no inhibitory effect on eruption (ANOVA P > 0.3) and crown development of the underlying permanent premolar but that Bio-Oss does not have the same resorbable or integrating capability as autogenous bone grafts.     

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.     

Peer approaches for increasing HIV awareness on a college campus

PURPOSE: To compare the accuracy of clinical examination performed with bitewing radiographs or clinical examination using tooth separation to identify carious lesion activity. MATERIALS AND METHODS: 320 surfaces from 40 bitewing radiographs were examined for approximal caries on the maxillary and mandibular primary molars of 20 patients 3-10 years old. The patients were divided into three groups: (1) Absence of the permanent first molar; (2) Partial eruption of the permanent first molar; and (3) Full eruption of the permanent first molar. Two examiners evaluated the radiographs using a megascope, a magnifying glass (x2), and an amplifying image screen. Approximal radiolucencies were identified on 72 surfaces. Following the radiographic examinations, the two examiners performed conventional clinical inspection using a No. 4 dental mirror, a No. 5 dental explorer, and an air-water syringe, with artificial light and relative isolation. The separation method was performed with elastic bands, which were removed after 24 hours, and the clinical examination conducted as in the non-separation group. RESULTS: The correlation between the extension of interproximal radiolucent lesions in primary dentition and their clinical diagnoses following separation of the teeth, was similar to findings on literature evaluating the permanent dentition. On radiographic findings for enamel lesions, white spots predominated both in the inner (100%) and in the outer (94%) half of enamel upon clinical examination with separation of teeth. For radiolucent lesions in dentin, on the other hand, cavities predominated over white spot lesions (84%). In Groups 1 and 2 (young primary), white spots occurred in cases where the radiolucent lesions reached the dentin (15% and 25%), similar to findings for young permanent teeth. Clinical diagnosis performed with the mechanical separation of teeth cannot be considered conclusive for the primary dentition.     

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.     

"Carious" and "noncarious" lesions of the hard dental tissues. Ultrastructural (SEM) and microanalytical (EDS) analyses of teeth from the 3rd century B.C

The study was carried out on 80 teeth (70 of permanent dentition and 10 of primary one) of mandibular and maxillary bones. The teeth owned to subjects lived in the III c.b.C. in Sicily, and they were found in Naxos necropolis. The teeth were examined as far as carious and non carious lesions, then they were prepared for instrumental analyses by Scanning Electron Microscopy (SEM) and Energy dispersed X ray spectrometry (EDS). To an objective examination of the sample no caries were detected in the teeth sample apart one tooth, on the other hand there was an extensive occlusal abrasion, from a macroscopic point of view there were no difference as far teeth morphology. SEM examination pointed out all around dentinal tubules a circle of sclerotic dentin as reaction to occlusal wear. The amelocemental junction showed from a ultramicroscopic point of view an overlap of cementum onto enamel. EDS analysis pointed out a higher P concentration on the crown versus the root in all the teeth of the sample.     

Nerve degeneration within the dental pulp after segmental osteotomies in the baboon (Papio ursinus)

Following dentofacial surgical procedures, teeth in segments often do not sense thermal or electric stimuli. This study was undertaken to assess changes in the neural component of the dental pulp after posterior maxillary and mandibular segmental osteotomies, with or without interpositional autogenous bone grafting, in 26 Chacma baboons. Innervation was assessed histologically immediately after operation, and at 3, 6, 12 and 18 months. Statistically significant differences were present between the experimental and control groups. Even after 18 months no nerves were present in any of the mandibular teeth. In maxillary teeth, 50 per cent had demonstrable nerves in the graft group and 40 per cent in the no graft group. As nerve degeneration was present in the experimental teeth, patients should be warned of possible change in tooth sensibility, following these operations. Careful post-operative follow up for long periods in humans following dentofacial surgical procedures is thus essential.     

Computerized 3-D reconstruction of two "double teeth"

"Double teeth" is a root malformation in the dentition and the purpose of this study was to reconstruct three-dimensionally the external and internal morphology of two "double teeth". The first set of "double teeth" was formed by the conjunction of a mandibular molar and a premolar, and the second by a conjunction of a maxillary molar and a supernumerary tooth. The process of 3-D reconstruction included serial cross-sectioning, photographs of the sections, digitization of the photographs, extraction of the boundaries of interest for each section, surface representation using triangulation and, finally, surface rendering using photorealistic effects. The resulting three-dimensional representations of the two teeth helped us visualize their external and internal anatomy. The results showed: a) in the first case, fusion of the radical and coronal dentin, as well as fusion of the pulp chambers; and b) in the second case, fusion only of the radical dentin and the pulp chambers.