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At least 541 records · Page 30Linked to original sources
PubMed2000

Radix mesiolingualis and radix distolingualis in a collection of permanent maxillary molars.

Two lingual root structures are occasionally found on human permanent maxillary molars. One of these is the normal lingual root, which is always present, the other is a supernumerary structure which can be located either mesiolingually (radix mesiolingualis (RML)) or distolingually (radix distolingualis (RDL)). The available literature refers only to the existence and location of RML and RDL Very small materials have, quite simply, hitherto precluded a more detailed description of these roots. The large collection of extracted teeth at the School of Dentistry in Copenhagen now includes a non-random subcollection of 145 permanent maxillary molars, the root complex of which contains 2 lingual root structures. Based on this material it was possible to undertake a modern, systematic analysis of the macromorphological variation of RMLs and RDLs. In this study, which was mainly non-metric, criteria for the identification of RML and RDL were established. The analysis also showed that the lingual supernumerary roots were only rarely found on the first molar, but with increasing frequency on the second and third molars. Both separate and non-separate RML and RDL were observed. In the material, degrees of separation greater than 0.9 were registered, degrees of divergence up to approximately 45 degrees, an apical bend of approximately 90 degrees, and extreme apical slenderness. Even though the supernumerary roots described here do not occur very often, knowing about them is nevertheless clinically relevant in for example endodontic and surgical contexts.

Humans↗
PubMed2002

Treatment time of traumatic dental injuries in a cohort of 16-year-olds in northern Sweden.

The aim of the present study was to account for treatment time and number of visits required for treatment of traumatic dental injuries in a cohort of 16-year-olds, born in 1975, and residing in the county of Västerbotten, Sweden, and to analyze the correlation between total treatment time and background factors. The study material comprised 1012 dental records from the Public Dental Health Service containing information on dental injuries to primary and/or permanent incisors or canines. The mean total treatment time per individual was 1.3 h, with a range of 0.1 to 27.5 h. For injuries to the primary dentition, the mean number of visits per individual was 2.2. One visit was sufficient in 21% of the trauma episodes. In the permanent dentition, each trauma episode required a mean of 3.4 visits, and 90% of the patients had to return for follow-up visits. The correlation between explanatory variables and total treatment time was described and analyzed by linear multiple regression analyses. Degree of severity and number of injured teeth were two parameters of major significance to treatment time. Treatment by a specialist had an impact on time in the permanent but not in the primary dentition. In the permanent dentition, the treatment time increased if the dental injury occurred before the age of 11 years. Treatment time was not dependent on where the clinic was located or on gender of the injured child. Different diagnoses could explain 33% of the variation in treatment time in the permanent dentition.

Adolescent↗
PubMed2003

Assessment of dysplastic dentin in osteogenesis imperfecta and dentinogenesis imperfecta.

Two semiquantitative scoring systems, Clinical Radiographic Score (CRS) and Dysplastic Dentin Score (DDS), were introduced for analyzing degree of dysplastic manifestations in dentin. The utility of both systems was demonstrated in a large material of teeth from patients with dentinogenesis imperfecta (DI) and osteogenesis imperfecta (OI). Twenty teeth from healthy controls, 81 teeth from 40 patients with OI, and 18 teeth with DI without OI (DI type II) were examined. The degree of dysplasia was correlated with type and form of OI and type of DI. The median DDS did not differ between DI associated with OI (DI type I) and DI type II. DDS in OI patients without clinical signs of DI was above that of control teeth. Both circumpulpal and mantle dentin showed increased DDS, although circumpulpal dentin was more severely affected. The median DDS was highest for the most severe type of non-lethal OI (type III). DDS increased significantly with form (severity) of OI. A significant association between DDS and CRS was found, although diagnosis of DI in less severe cases was not possible based on radiographic or clinical signs alone. Thus, the DDS system proved valuable when the CRS system based on radiographic/clinical manifestations failed, the most significant finding being subclinical histological manifestations of DI in patients with OI but without clinical or radiographic signs of DI. These subtle dysplastic changes are most likely an expression of genetic disturbances associated with OI and should not be diagnosed as DI, but rather be termed histologic manifestations of dysplastic dentin associated with OI.

Adult↗
PubMed2004

A premaxilla with a supernumerary tooth indicating a developmental region with a variety of dental abnormalities: a report of nine cases.

The aim of this study was to elucidate whether a premaxilla with a supernumerary tooth has additional dental abnormalities. The study does not include premaxillas with a mesiodens, only premaxillas with parasagittally located supernumerary teeth. Radiographs from eight children, followed from 1 year and 5 months to 11 years and 5 months in the municipal dental health service in Denmark, were analyzed. One patient was seen only once. Dental abnormalities recorded included: invaginations on permanent incisors, resorption of roots of incisors, curved roots of incisors, delayed eruption, and delayed formation of roots. The study shows that there are dental abnormalities within the premaxillary region where the supernumerary tooth is located. This indicates that, apart from the supernumerary tooth, a more widespread deviation from normal conditions including tooth malformation, arrested eruption, and root resorption occur within the premaxillary region. The most important outcome of this study is that in the region with a supernumerary tooth the adjacent incisor shows delayed eruption after surgical removal of the supernumerary tooth. The deviations in root morphology, including root resorption, are not limited to patients who have had orthodontic treatment, but patients who did not receive orthodontic treatment also revealed deviations in root morphology. Therefore the treatment outcome can be different from the expected outcome.

Adolescent↗
PubMed2006

Facial talon cusp in primary maxillary lateral incisor: a report of two unusual cases.

Talon cusp is an uncommon dental anomaly in which an accessory cusp-like structure projects from the cingulum area or cemento-enamel junction of the maxillary or mandibular anterior teeth. This anomalous cusp resembles an eagle's talon. It occurs in both the primary and the permanent dentition. A comprehensive literature review shows that only 37?cases of talon cusps have been reported in the primary dentition, of which only 4?cases report this anomaly on the primary maxillary lateral incisor. Though labial/facial talon cusps have been reported in the permanent dentition, no case of a labial talon has been reported in the primary dentition. We report two females with cleft lip and palate with facial talon cusps on the primary lateral incisor and believe that these are the first cases to be reported. Clinical considerations and debate on the etiology of this anomaly are discussed.

Child↗
PubMed1991

Nutritional supplementation and the development of linear enamel hypoplasias in children from Tezonteopan, Mexico.

The purpose of this study was to compare the effect of nutritional intake during tooth-crown formation on the subsequent development of linear enamel hypoplasias (LEHs) in Mexican nonsupplemented (control) adolescents (n = 42) and adolescents who had received daily nutritional supplements since birth (n = 42). The proportion of individuals with LEHs was nearly two-fold greater (74.4%; 95% CI 64.7-84.1%) in the control than in the supplemented group (39.5%; 95% CI 28.6-50.4%; chi 2 = 9.44; P = 0.001). Although the estimated peak age at formation, approximately 2-2.5 y, is similar in both groups, the proportion of early (before 1.5 y) and late (after 3.0 y) LEHs was greater in the control group. LEH was also more common in females and was associated with an increase in illness days and a decrease in growth velocity. Results of this study suggest that mild to moderate undernutrition during enamel formation is causally linked to the formation of LEHs.

Anthropometry↗
PubMed1999

The length and eruption rates of incisor teeth in rats after one or more of them had been unimpeded.

The eruption rate and length of all four incisor teeth in rats were measured under ether anaesthesia by recording the position of marks on their labial surfaces at 2-day intervals, using calibrated graticules in microscope eyepieces. The rats were divided into four groups and either a lower, an upper, both a lower and an upper, or no incisors were unimpeded. This paper describes the changes when the unimpeded incisors returned to the occlusion. Neither the unimpeded nor the impeded incisors simply returned to control values immediately the period of unimpeded eruption ended, but showed transient changes in their lengths and eruption rates. The results confirm that eruption rates are determined by the sum of the lengths of the lower and upper incisors, rather than by their own lengths, with longer teeth erupting more slowly. Specifically, restoring the bevel to the incisors did not slow their eruption below normal impeded rates. The slowing of the eruption of the longer of two adjacent incisors was related to the length differences of the incisors in the same jaw, not to the sum of the differences in both jaws. Contact with the contralateral incisor in the opposite jaw slowed the eruption of an incisor more than contact with the ipsilateral incisor.

Analysis of Variance↗
PubMed1999

Longitudinal post-eruptive mandibular tooth movements of males and females.

Unbiased estimates of post-eruptive eruption and migration of the mandibular teeth for large representative samples are presently unavailable. The purpose of this study was to evaluate pure tooth movements of untreated children and adolescents longitudinally. Lateral cephalograms of 214 French-Canadians, followed bi-annually between 8 and 15 years of age, were traced, and the positions of the mandibular permanent central incisors and first molars were digitized. Temporal changes in tooth position were evaluated relative to naturally stable mandibular reference structures, using the mandibular reference line for orientation. The statistical analyses included t-tests to assess gender differences and Pearson product-moment correlations to evaluate associations. The results showed that the incisors proclined significantly more for males (6 degrees) than females (3 degrees). The incisor tips displayed early mesial movements that were countered by later distal movements. The incisor apex showed a consistent pattern of distal migration between 8 and 15 years. Mandibular arch length decreased over the 7-year observation period. Rates of mesial molar migration accelerated until 11 years of age and then decelerated. There was no significant change in the mandibular occlusal plane angle between 8 and 15 years of age. Incisor eruption showed the greatest rates during adolescence, attaining peaks at approximately 12 years for females and 14 years for males. The molars erupted approximately 5 mm between 8 and 15 years of age. The greatest gender differences occurred at the older ages, with males showing greater eruption potential than females. It was concluded that the mandibular teeth show significant migration and eruption during childhood and adolescence, with gender differences in the amount, direction, and timing of movement.

Adolescent↗
PubMed1999

Blood vessel response to pan-endothelium (RECA-1) antibody in normal and tooth loaded rat periodontal ligament.

Immunolabelling of the normal rat molar periodontal ligament (PDL) with RECA-1 antibody, an endothelial cell surface marker, demonstrated the endothelium in the different categories of blood vessels. The intensity of immunolabelling was similar for venous capillaries (VC), post-capillary-sized venules (PCV), and collecting venules (CV). Arterial capillaries (AC) and terminal arterioles (TA) showed a different response, both having a high intensity of endothelium and smooth muscle cell labelling, whether they were located in the PDL or alveolar bone. An experimental, continuous loading of approximately 100 g was applied unilaterally to the mandibular molars for 10 minutes. In the PDL apical compression zone this load resulted in a loss of RECA-1 immunolabelling of the VC, PCV, and CV. Adjacent to the alveolar crest, where shear and tension loads were judged to have occurred, there was enhanced immunoreactivity of VC, PCV, and CV. In the loaded PDL, the AC and TA, irrespective of their location in the ligament or bone, showed strong immunofluorescence of their endothelium and the enveloping smooth muscle layer. Vessel and PDL immunofluorescence were analysed with standardized grey scale densitometry, and the data subjected to ANOVA. Comparison between individual vessel means showed significant differences (P < 0.05). Control teeth showed no immunostaining difference between the coronal and apical region vessels, whereas in the loaded teeth the overall cervical vessel endothelium had a significantly higher value than the apical vessel endothelium (P < 0.001). These findings demonstrate that the endothelium of this microvascular bed can undergo significant immunoreactivity changes when exposed to short-term, continuous, tooth loading.

Alveolar Process↗
PubMed1999

The effect of tooth position on the image of unerupted canines on panoramic radiographs.

The purpose of this study was to evaluate whether panoramic tomograms, which are routinely used in orthodontic practice, can provide adequate information to localize an impacted canine. The effect of changes in position and inclination of an impacted canine on orthopantomograms was investigated in an experimental set-up. An upper canine was removed from a human skull and replaced in a positioning system, enabling simulated positional variations in impactions. In comparison with the image of a contralateral well-aligned canine, the length of the impacted tooth always decreased or remained unchanged, whereas the tooth width increased or remained unchanged. The angulation of the image was unaffected by varying the position of the impacted canine, but altered when the inclination of the tooth in a sagittal or frontal direction was changed. If there was any transversal shift of the impacted canine on the orthopantomogram, it was always towards the mid-sagittal plane. The curvature of the tooth increased after dorsal inclination and decreased after ventral inclination (in comparison with the contralateral well-aligned canine).

Cephalometry↗
PubMed2000

A mathematic-geometric model to calculate variation in mandibular arch form.

A mathematic-geometric model was used to evaluate the variation of mandibular dental arch length with respect to the incisor inclination, but without modifying the intercanine width. In analytical terms, the equations of the curves representing the lower dental arch, before and after incisor inclination of 1 mm and of 1 degree, with controlled and uncontrolled tipping, were studied. The length of the mandibular dental arch changed in the parabolic arch form by 1.51 mm for each millimetre of incisor inclination with respect to the occlusal functional plane, by 0.54 mm for each degree of controlled tipping and by 0.43 mm for each degree of uncontrolled tipping. In the elliptical arch form (e = 0.78), it changed by 1.21, 0.43, and 0.34 mm, respectively, in the hyperbolic form by 1.61, 0.57, and 0.46 mm, in the circular form by 1.21, 0.43, and 0.34 mm, and in the catenary form by 2.07, 0.74, and 0.59 mm. The results show that by changing the arch form without modifying the dimension of the dental arch, different arch lengths can be gained for each millimetre of proclination. In addition, by controlled tipping an inter-incisive arch one-fifth longer than by uncontrolled tipping can be obtained. It would be advisable in orthodontic treatment planning to evaluate the type of dental arch, since the space available or the space required changes depending on the arch form and on the orthodontic tooth movement.

Algorithms↗
PubMed2001

Relationships among facial type, buccolingual molar inclination, and cortical bone thickness of the mandible.

The purpose of this study was to evaluate the relationships between different facial types, and both the buccolingual molar inclination and cortical bone thickness of the mandible. The material consisted of 31 dry skulls of modern Japanese males from the Museum of the University of Tokyo. They all demonstrated normal occlusion with minimal dental discrepancy, and without crossbite or facial asymmetry. The buccolingual inclination of the second molar (M2) in the long-faced subjects was significantly smaller than the same dimension in the average- and short-faced subjects. It was found that the teeth of long-faced subjects were more lingually inclined than those of the short-faced subjects. The cortical bone thickness of the first molar (M1) and M2 sections was thicker in short-faced subjects than in average- and long-faced subjects. The results of this study provide evidence that a significant, but complex relationship exists between structures of the mandibular body and facial types. The morphological features that relate to masticatory function and facial types are associated with the cortical bone thickness of the mandibular body, and the buccolingual inclination of the first and second molars.

Adolescent↗
PubMed2001

Tissue reaction to orthodontic tooth movement--a new paradigm.

Direct or indirect resorption are both perceived as a reaction to an applied force. This is in contrast to orthopaedic surgeons who describe apposition as 'the reaction to loading of bone'. The article reviews the literature on intrusion of teeth with periodontal breakdown, and on the basis of clinical and experimental studies. The conclusion is reached that intrusion can lead to an improved attachment level, and that forces have to be to low and continuous. The tissue reaction to a force system generating translation of premolars and molars in the five Macaca fascicularis monkeys is described. Three force levels, 100, 200, and 300 cN were applied for a period of 11 weeks. Undecalcified serial sections were cut parallel to the occlusal plane and a grid consisting of three concentric outlines of the root intersected by six radii was placed on each section so that areas anticipated to be subject to differing stress/strain distributions were isolated. A posteriori tests were utilized in order to separate areas that differed with regard to parameters reflecting bone turnover. Based on these results and a finite element model simulating the loading, a new hypothesis regarding tissue reaction to change in the stress strain distribution generated by orthodontic forces is suggested. The direct resorption could be perceived as a result of lowering of the normal strain from the functioning periodontal ligament (PDL) and as such as a start of remodelling, in the bone biological sense of the word. Indirect remodelling could be perceived as sterile inflammation attempting to remove ischaemic bone under the hyalinized tissue. At a distance from the alveolus, dense woven bone was observed as a sign of a regional acceleratory phenomena (RAP). The results of the intrusion could, according to the new hypothesis, be perceived as bending of the alveolar wall produced by the pull from Sharpey's fibres.

Alveolar Bone Loss↗
PubMed2003

The effect of changes in tooth position of unerupted canines on cephalograms.

Although many radiographic procedures have been described to localize an impacted canine, they all submit the patient to extra radiation. The purpose of the entire study was to evaluate if the combined interpretation of cephalograms and dental panoramic tomograms (DPTs), which are used in orthodontic practice, can provide adequate information as to the position of impacted canines. In a previous study the radiographic image of impacted canines on DPTs was evaluated. In this investigation, the effect of changes in position and inclination of an impacted canine on cephalograms was studied in an experimental set-up. An upper canine was removed from a human skull and placed in a positioning device to imitate various positions of impaction. Starting from a buccally impacted position, three different displacements were simulated: 10 mm frontally, 10 mm sagittally, and 5 mm vertically. In each of these positions nine different changes in inclination (in the sagittal and the frontal plane) were registered, resulting in 36 different cephalographic exposures. Analysis revealed the following: the degree of vertical and sagittal displacement of the incisal point of the impacted canine, the angulation of the tooth as well as the tooth length, measured on a cephalogram, appeared to give an accurate representation of the experimental set-up. Combining these findings and those from the previous study, it became possible to define a series of points to enable an adequate three-dimensional (3D) estimation of the canine's position. A clinical case of an impacted canine is used as an illustration of this experimental set-up.

Cephalometry↗
PubMed2003

Photo-elastic stress analysis of initial alignment archwires.

Photo-elastic models replicating a lower arch with a moderate degree of lower incisor crowding and a palatally displaced maxillary canine were used to evaluate the stresses transmitted to the roots of the teeth by initial alignment archwires. Six initial alignment archwires were compared, two multi-strand stainless steel wires, two non-super-elastic (stabilized martensitic form) nickel titanium wires, and two stress-induced super-elastic (austenitic active) nickel titanium wires. Three specimens of each archwire type were tested. Analysis of the photo-elastic fringe patterns, in the medium supporting the teeth, revealed that the non-super-elastic nickel titanium archwires produced the highest shear stresses (P = 0.001). However, the shear stresses generated by the super-elastic alignment archwires and the multi-strand stainless steel archwires were very similar (P = 1.00). These results show that even in situations where large deflections of initial alignment archwires are required, super-elastic archwires do not appear to have any marked advantage over multi-strand stainless steel alignment archwires in terms of the stresses transferred to the roots of the teeth.

Analysis of Variance↗
PubMed2003

Tooth size in dentitions with buccal canine ectopia.

Much interest has been expressed in recent years regarding various features common to dentitions with palatally displaced canines (PDC), particularly in relation to delayed dental development and reduced tooth size. The aims of the present study were to determine whether dentitions with buccally displaced canines (BDC) have features in common, which may be specific for the condition, when compared with PDC dentitions and those with normally erupting canines. Mesiodistal and buccolingual tooth dimensions were determined for 41 subjects with BDC (21 females and 20 males) aged between 11 and 15 years, who formed the experimental sample. The PDC sample was made up of 58 individuals (37 females and 21 males) and the control group comprised 40 age-matched and consecutively treated subjects (20 males and 20 females), exhibiting normally erupted and undisplaced maxillary canines. The results revealed marked sexual dimorphism. Larger-than-average teeth were present in BDC females, whereas the teeth in BDC males were normally sized. Unilaterally affected females had smaller teeth than bilaterally affected females. Tooth size in BDC was consistently larger than in PDC subjects, although the reason was different between the sexes. In females the PDC teeth were normally sized versus large BDC teeth, whereas in the males, the PDC teeth were small and the BDC teeth normal. It is concluded that combining male and female subjects into an overall BDC group obscures important differences that exist between the two sexes.

Adolescent↗
PubMed1997

Morphology of anterior teeth associated with displaced canines.

This clinical study compared tooth dimensions of maxillary central and lateral incisors on the same side as a palatally impacted maxillary canine with those of the contralateral side with a normally erupted canine, in a group of 33 consecutively referred patients. The dimensions recorded were the mesio-distal width, labio-palatal depth, obtained from models of the four upper anterior teeth and total tooth length obtained from an orthopantomographic radiograph. The results showed that there was no statistically significant evidence to support the view that palatally impacted maxillary canines are associated with diminutive maxillary lateral incisors.

Adolescent↗