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PubMed2002

Patterning of human dental arch wire blanks using a vector quantization algorithm.

We objectively and automatically classified arch wire blank forms represented by a series of facial surface points on tooth crowns in human adults with normal occlusions using a vector quantization algorithm on the basis of the generalized Lloyd algorithm. We investigated also the descriptive dental arch form parameters that were most effective in distinguishing the classified groups of dental arch wire blanks and examined if they were associated with specific anatomical traits. Dental casts, taken from 79 adults with complete dentitions, were laser scanned with a computer-assisted stereotaxic device. Coordinates of the tooth crown points (FA points) were measured for each dental arch expressed as a vector having positional elements in a series of 14 FA points and categorized into several codes (ie, patterns) according to the similarity of the quantized vector patterns. We found that classifying the dental arches into four patterns maximized the difference between arch wire blank patterns. The classified patterns were differentiated by a gradual broadening of the interarch widths posterior to the lateral incisor. The code with the narrowest arch had the longest coronal arch, whereas the code with the widest arch had the shortest coronal arch (P < .01). The interpremolar and intermolar basal arch widths determined for the code showing the widest arch were significantly greater than those for the code with the narrowest width (P < .01).

Adult↗
PubMed1996

Prediction of coronal size of third molars by factor and multiple regression analyses.

Factor analysis and multiple regression analysis were made to establish a method for the prediction of the unerupted third molar size. The samples were dental casts of 138 adults (69 women and 69 men) who had all their teeth from the central incisor to the third molar, at least in one side of each maxillary and mandibular dentition. Mesiodistal and buccolingual tooth crown sizes were measured with sliding calipers. Five factors were selected from the factor analysis on the tooth crown sizes. Multiple regression analysis with the third molar as the dependent variable was carried out. Independent variables were selected on the basis of the factors obtained from the factor analysis. Two kinds of multiple regression equations were obtained (the first molar was used as an independent variable in one equation and the second molar was used in the other). The accuracy of the prediction was highest when the lateral incisor, the second premolar, and the second molar were used as independent variables in the maxillary dentition, and the central incisor, the first premolar, and the second molar in the mandibular dentition. The mean of the absolute values of the differences between the predicted values and the actual values was 0.5 mm in the maxillary third molar, and 0.42 mm in the mandibular third molar.

Adult↗
PubMed2005

Variability of the cranial and dental phenotype in Williams syndrome.

INTRODUCTION: Williams syndrome (WS) is a rare congenital disorder involving the cardiovascular system, connective tissue, and the central nervous system, resulting in mild to moderate mental retardation, a specific cognitive profile, unique personality characteristics, distinctive facial features, and cardiovascular disease. The majority of individuals with a clinical diagnosis of WS have a contiguous gene deletion at chromosome 7 (7q11.23). Physical features include characteristic facial features with full prominent cheeks, wide mouth, long philtrum, small nose with depressed nasal bridge, heavy orbital ridges, medial eyebrow flare, dental abnormalities, hoarse voice, growth retardation, and cardiovascular abnormalities (most commonly supravalvular aortic stenosis and/or peripheral pulmonary artery stenosis). The cognitive profile is distinctive, consisting of strengths in auditory memory, language, and face-processing, but extreme weakness in visuospatial, numerical and problem-solving abilities. Neurological studies have identified a significantly decreased brain volume in adult individuals with WS with relatively normal development of the limbic, frontal and cerebellar structures. AIMS: The aims were to analyse the neurocranium, the craniofacial region, and the dentition in a well defined Norwegian group of individuals with WS. In order to accomplish this, normative cephalometric standards for the neurocranium, including the cranial base and the sella turcica, were established for Norwegian males and females from 6 to 21 years of age, using lateral radiographic cephalograms from the Oslo University Craniofacial Growth Archive. MATERIAL AND METHODS: The study material comprised radiographic lateral cephalograms, orthopantomograms and dental casts from 62 individuals with WS ranging from 4 to 44 years. The lateral cephalograms, orthopantomograms and dental casts were analysed using standard methods reported in the literature. RESULTS: Neurocranium: The results from the cephalometric analyses showed that the size and shape of the neurocranium in WS differed from normal controls. A flattening of the superior aspect of the parietal bone was found and the posterior prominence of the occipital bone was larger. These findings were in concordance with published neuroanatomical/neuropathological studies on WS and fit well with the reported anatomical aberrations in the WS brain, e.g. a smaller brain volume where some parts are of relatively normal size while others are decreased. The anterior and posterior cranial base was shorter in WS, but with a normal cranial base angle. The thickness of the calvarian bones, especially the frontal and occipital bones, was greater in WS than in normal controls. Sella turcica: The size of the sella turcica was somewhat smaller in WS compared with normal controls, though not significant. Aberrant types of shape of the sella turcica in WS are demonstrated. The correlation between prenatal malformation in the pituitary gland/sella turcica and the postnatal morphology of the sella turcica is discussed. The craniofacial skeleton: Two areas, in addition to the cranial base, have been identified to contribute to the characteristic facial appearance in WS; the anterior inclination of the maxilla, and the shape of the mandible. The severely deficient bony chin in combination with the high mandibular plane angle can explain earlier clinical descriptions of a retrusive mandible in WS. Frequent mouth breathing during childhood and the smaller cranial base may be associated with the characteristic craniofacial pattern. Dentition: In individuals with WS over 10 years of age 40.5 per cent had agenesis of one or more permanent teeth and 11.9 percent had agenesis of 6 teeth or more. The missing permanent teeth in the maxilla most commonly included 2nd premolars, 1st premolars, and lateral incisors. In the mandible most commonly 2nd premolars, 1st premolars, and central incisors were absent. The tooth crowns of permanent teeth were smaller, both in the mesio-distal and labio-lingual dimension. The permanent tooth crowns have several characteristic deviations from normal shape; especially incisors in both jaws were tapered or screwdriver-shaped. An evaluation of taurodontism on permanent molars was performed. However, most of the molars rated as being taurodontic had short total tooth lengths and could thus be rated taurodontic without meeting the classical definition. CONCLUSIONS: These studies have shown aberrations in the neurocranium including the sella turcica in WS not previously reported. In the craniofacial skeleton specific traits have been identified to contribute to the characteristic facial appearance in WS. Dental aberrations in the permanent dentition including agenesis, smaller size, and aberrant shape of teeth, are common in WS.

Adolescent↗
PubMed2005

Alternative dental measurements: proposals and relationships with other measurements.

Most archaeological and fossil teeth are heavily worn, and this greatly limits the usefulness of tooth crown diameter measurements, as they are usually defined at the widest points of the crown. There are alternatives, particularly measurements at the cervix of the tooth, where the crown joints the root, and measurements along a diagonal axis in molars, that are much less affected by wear. These would allow a wider range of specimens to be included, e.g., in the study of dental reduction in Upper Palaeolithic and Mesolithic Homo sapiens. In addition, they would allow the little-worn teeth of children to be compared directly with well-worn teeth in adults. These alternatives, however, have been little used, and as yet there have not been any studies of the repeatability with which they can be measured, or of the extent to which they are related to the more usual crown diameters. The present study is based on a group of unworn teeth, where direct comparisons could be made between the alternative measurements, which are not much affected by wear, with the usual crown diameters, which are very much affected. In an interobserver-error study of this material, cervical and diagonal measurements could be recorded as reliably as the usual crown diameters. The buccolingual cervical measurement was strongly correlated with the normal bucclingual crown diameter in all teeth, whereas the mesiodistal cervical measurement was highly correlated with the normal mesiodistal crown diameter in incisors and canines, but less so in premolars and molars. The molar diagonal measurements showed high correlations with all other measurements. Crown areas (robustness index) calculated from the usual diameters were strongly correlated with crown areas calculated from cervical measurements, and crown areas calculated from molar diagonals were strongly correlated with both other areas. Despite the long usage of the more usual maximum crown diameters, the alternative dental measurements could be measured just as reliably, could record similar information about tooth crown size, and would be better measures for the worn dentitions seen in archaeological and fossil material.

Fossils↗
PubMed2006

High-level similarity of dentitions in carnivorans and rodents.

The study of mammalian evolution depends greatly on understanding the evolution of teeth and the relationship of tooth shape to diet. Links between gross tooth shape, function and diet have been proposed since antiquity, stretching from Aristotle to Cuvier, Owen and Osborn. So far, however, the possibilities for exhaustive, quantitative comparisons between greatly different tooth shapes have been limited. Cat teeth and mouse teeth, for example, are fundamentally distinct in shape and structure as a result of independent evolutionary change over tens of millions of years. There is difficulty in establishing homology between their tooth components or in summarizing their tooth shapes, yet both carnivorans and rodents possess a comparable spectrum of dietary specializations from animals to plants. Here we introduce homology-free techniques to measure the phenotypic complexity of the three-dimensional shape of tooth crowns. In our geographic information systems (GIS) analysis of 441 teeth from 81 species of carnivorans and rodents, we show that the surface complexity of tooth crowns directly reflects the foods they consume. Moreover, the absolute values of dental complexity for individual dietary classes correspond between carnivorans and rodents, illustrating a high-level similarity between overall tooth shapes despite a lack of low-level similarity of specific tooth components. These results suggest that scale-independent forces have determined the high-level dental shape in lineages that are widely divergent in size, ecology and life history. This link between diet and phenotype will be useful for inferring the ecology of extinct species and illustrates the potential of fast-throughput, high-level analysis of the phenotype.

Animals↗
PubMed2003

The Periotest in traumatology. Part I. Does it have the properties necessary for use as a clinical device and can the measurements be interpreted?

The Periotest is a non-invasive, electronic device which provides an objective measurement of the reaction of the periodontium to a defined impact load applied to the tooth crown. In order for a clinician to interpret Periotest readings, normal physiological values must be known. In traumatology, using the contralateral tooth as a control is impractical, as it too may be affected by injury. The main purpose of this research project was to establish the normal physiological Periotest readings for upper permanent incisor teeth at an age when trauma to teeth is at a peak. This was achieved by taking Periotest readings on healthy upper permanent incisors of 250 children aged between 8-12 years. Test-retest reliability was investigated by taking repeated Periotest readings on the teeth of 13 dental nurses at timed intervals over a 2-h period. The practicality of using the device on children was examined by examiner observation and patient questionnaire. Results showed a wide variation of Periotest readings in healthy upper permanent incisor teeth in 8-12-year-olds, and thus it was felt that normal physiological measurements are best expressed as a range. The test-retest reliability of readings was good (R > 0.85) provided that the repeat reading was taken at least 15 min after the initial reading. The examiner found the equipment easy to use and taking measurement was readily acceptable by the sample group. It was concluded that Periotest could be utilised in traumatology, although the clinician needs to take into account the limitations of the device and the difficulty in interpreting the results.

Child↗
PubMed1988

Intradental nerve activity and jaw-opening reflex in response to mechanical deformation of cat teeth.

Mechanical stress was applied to canine teeth in anaesthetized cats to excite intradental A-fibres and to produce digastric muscle EMG responses. Activity in the intradental sensory units was recorded by two electrodes, one inserted in a dentinal cavity, the other in contact with the gingival sulcus. A pneumatically driven piston was used to cause a mechanical stress (10-150 N) on the stabilized tooth crown for 30 s, with instantaneous onset and release. Application of a load of 30 N produced a momentary burst of impulses in 2 of 12 teeth; 8 out of 10 teeth responded when 150 N was used. Digastric EMG responses were obtained at and above 60 N. Removal of the coronal pulp or cooling of the tooth crown with ethyl chloride abolished this reflex, whereas percussion of the tooth still produced a digastric response. Our results suggest that load-induced deformation of teeth activates intradental sensory mechanisms and a reflex withdrawal reaction unrelated to periodontal stimulation.

Animals↗
PubMed2005

Root growth in the teeth of 46,XY females.

The subjects of this study are women with a male sex chromosome complement or 46,XY females who show the complete form of the testicular feminization syndrome (CTF). The basic endocrine defect is end organ insensitivity to androgens. They are on average tall individuals and also show an increase in head and face dimensions relative to normal females. A size increase is likewise evident in permanent tooth crowns and here we report permanent tooth root lengths in eight 46,XY females, their five female relatives and population control females and males. Measurements were made from panoramic radiographs by a digital calliper according to established procedures on both sides of the jaws. The results show increased root lengths of 46,XY females relative to control females with values similar to those in population control males. The root and crown findings point to evident irreversible growth excesses in 46,XY females beginning 3 years after birth up to the age of 14 years expressing an effect which apparently is influencing in a continuous way. Excess root growth conceivably would develop independently of the possible androgen influence, and it is suggested that the increase results from the direct effect of the genes on the Y chromosome. It is possible that these genes on the Y chromosome are the same that promote tooth crown growth.

Androgen-Insensitivity Syndrome↗
PubMedDate not supplied

Internal bleaching with 10% carbamide peroxide in vitro.

This in vitro study assessed the efficacy of 10% carbamide peroxide to internally bleach discolored teeth. Following pulp removal, 38 tooth crowns were stained with erythrocytes and bleached 3 times over 14 days using either 10% carbamide peroxide or 30% H2O2 and sodium perborate. The pulp chambers were subsequently filled, and the tooth crowns stored for 3 months. The shades of the crowns were measured using reflectance spectroscopy prior to and at several time points following bleaching. Using statistical analysis, the authors determined that both materials significantly improved the shade of the crowns, and that 10% carbamide peroxide could be utilized clinically to internally bleach nonvital discolored teeth.

Analysis of Variance↗
PubMed1996

Comparison of the crown dimensions between the maxillary second deciduous molar and the first permanent molar.

The morphologic relationship of the crown structures of the maxillary second deciduous molar (m2) and the first permanent molar (M1) was investigated with odontometric methods. Materials used were 124 male dental casts taken from Chinese living in Kaohsiung (Taiwan). The mesiodistal and buccolingual diameters, cusp sizes, and intercusp distances were measured. The mean crown diameters were larger in M1 than in m2. The tooth crown proportions were similar in m2 and M1. The intercusp distance was compressed buccolingually in m2. With respect to the relative cusp size, the paracone was not significantly different between m2 and M1. The metacone was relatively larger in m2 than M1, while lingual cusps (protocone and hypocone) were relatively smaller in m2 than in M1. Principal component analysis was performed to investigate factors influencing the variation in crown dimensions of the two teeth. Four components were extracted: (1) buccolingual intercusp distances, (2) crown proportion (mesiodistal and buccolingual diameters), (3) mesiobuccal and distolingual compression, and (4) protocone and mesiodistal intercusp distance. Analysis of principal component scores indicated that the crown proportions of m2 and M1 were similar. The m2 had a smaller protocone and more buccolingually compressed intercusp distances than did M1. The morphologic characteristics of the crown of m2 indicate that it is more primitive and has developed less than M1.

Humans↗
PubMed1980

Microleakage of composite resin and amalgam core material under complete cast crowns.

Ninety extracted human teeth were used to compare the microleakage of composite resin over, amalgam core, and regular crown preparations under a complete cast gold crown cemented with zinc phosphate cement as determined by 2% fluorescein dye solution. Specimens were compared with and without aging after cementation in a thermal bath by cycling some of them between 4 degrees C and 60 degrees C in a 2% fluorescein dye bath and others in a similar bath held at 37 degrees C. Fluorescein dye (under ultraviolet light) demonstrated microleakage of the specimens between the crown-tooth interface and the core-tooth interface. There were no significant differences in the microleakage due to aging. The specimens held at 37 degrees C in the fluorescein dye bath showed no significant differences between the core preparations and the regular crown preparations. However, when specimens were thermally cycled between 4 degrees C and 60 degrees C, there were significant differences. With thermal cycling, the regular crown preparations were better able to resist microleakage at the crown-tooth interface than either the composite resin core or the amalgam core preparations. The results of this investigation seem to indicate a need for further evaluation of core build-ups under cemented complete gold crowns.

Composite Resins↗
PubMed2004

Modulation of activin/bone morphogenetic protein signaling by follistatin is required for the morphogenesis of mouse molar teeth.

Teeth form as ectodermal appendages, and their morphogenesis is regulated by conserved signaling pathways. The shape of the tooth crown results from growth and folding of inner dental epithelium, and the cusp patterning is regulated by transient signaling centers, the enamel knots. Several signal proteins in the transforming growth factor-beta (TGF beta) superfamily are required for tooth development. Follistatin is an extracellular inhibitor of TGF beta signaling. To investigate the roles of follistatin during tooth development, we analyzed in detail the expression patterns of follistatin, activin beta A, as well as Bmp2, Bmp4, and Bmp7 during tooth morphogenesis. We also examined the tooth phenotypes of follistatin knockout mice and of transgenic mice overexpressing follistatin in the epithelium under the keratin 14 (K14) promoter. The folding of the dental epithelium was aberrant in the molars of follistatin knockout mice, and the cusps were shallow with reduced cell proliferation and lack of anteroposterior polarization. The functions of both primary and secondary enamel knots were apparently disturbed. In K14-follistatin transgenic mice, the molar cusp pattern was also seriously affected (although different from the follistatin knockouts) and the occlusal surfaces of the molars were whorled. Their enamel was prematurely worn. In addition, all of the third molars were missing. Our results indicate that follistatin regulates morphogenesis and shaping of the tooth crown. We propose that finely tuned antagonistic effects between follistatin and TGF beta superfamily signals are critical for enamel knot formation and function, as well as for patterning of tooth cusps.

Activins↗
PubMed2005

Halitosis manifestation and prevention means for patients with fixed teeth dentures.

The objective of this research is to analyse the causal relationship between construction of fixed bridge dentures and the intensity of halitosis manifestations, as well as to establish basic hygiene requirements for construction of fixed dentures which would completely exclude retention of food particles and avoid bad breath. 48 patients (36 men and 12 women), who use fixed dentures for 2-10 years, have been involved in this research. 26 patients wore fixed bridge dentures made of punched tooth crowns, the other 22 patients wore cast fixed dentures. The obtained measurements of halitosis magnitude point to the close connection between bad breath and the construction of fixed dentures. Fixed dentures with tooth crown laps, saddle intermediate parts, as well as denture constructions, which impede complex of mouth hygiene measures, cause bad breath. In this research, the condition of patients' teeth, periodontium, and oral cavity hygiene have been evaluated as satisfactory; the tongue is not perceptibly coated, and patients etiologically have not experienced problems caused by respiratorial or gastrointestinal diseases. The examined patients have not complained of xerostomia problems. In conclusion, it should be admitted that fixed dentures, which make difficult or even completely impede the complex of oral cavity hygiene measures, intensify the development of halitosis.

Adult↗
PubMed2003

Maxillary odontogenic keratocyst with respiratory epithelium: a case report.

We report a case of odontogenic keratocyst with a respiratory epithelial lining and a malformed impacted tooth in the maxilla of a 39-year-old Japanese female who suffered from swelling symptoms for half a year. CT examinations revealed an air-filled cystic lesion with an impacted tooth crown in the maxillary bone which expanded to the nasal cavity as well as to the maxillary sinus. Histopathologically, the surgically removed cyst wall consisted of fibrous granulation tissue with a lining of parakeratinized squamous epithelium as well as ciliated pseudostratified epithelium and with retention of desquamated keratin materials in the lumen. The impacted tooth was malformed lacking a root portion. We discuss the frequency of respiratory epithelium in odontogenic keratocysts.

Adult↗
PubMed1990

[Familial gingival fibromatosis: report of a case].

One family of familial gingival fibromatosis was presented. Case 1 is an 11 years old girl. Gingival fibromatosis was noted by delayed eruption of permanent teeth. Fibromatosis was seen in whole gingiva and lower 1/2 to 1/3 of the tooth crowns was covered. Gingivectomy was performed. Case 2 was 42 years old man, who was father of case 1. Firstly gingival swelling was noted at the age of 10 years. He had operations of gingivectomy at the age of 28 years. It recurred and fibromatosis was seen in whole gingiva and lower 1/2 to 1/3 of the tooth crowns was covered. Cytogenetically no abnormality was seen in the chromosomes of both cases. Reported cases of familial and non-familial gingival fibromatosis in Japan were reviewed.

Adult↗
PubMed1998

[Clinicopathological investigations of the dental diseases caused by maxillary lesions].

Clinicopathological investigations of five surgery-requiring dental diseases caused by maxillary lesions were conducted. 1) The maxillary lesions were acute maxillary sinusitis and a postoperative maxillary cyst. 2) The clinical symptom was persistent cheek pain, even though the maxillary lesions were improved and there were no lesions in the tooth crown or periodontal tissue. 3) All of the teeth with dental diseases caused by maxillary lesions had percussion pain. 4) The pathological findings of the dental diseases were ascending pulpitis and pulpal necrosis caused by maxillary lesions. 5) When patients complain of persistent cheek pain even though maxillary lesions are improved and there are no lesions of the tooth crown or periodontal tissue, we should doubt the presence of dental diseases caused by maxillary lesions (ascending pulpitis and pulpal necrosis).

Acute Disease↗
PubMed2004

Risk indicators for posterior tooth fracture.

BACKGROUND: Identifying posterior teeth that are at heightened risk of developing cusp fracture is an inexact science. Risk indicators based on controlled observations are not available, and dentists' assessments vary. METHODS: The authors conducted a case-control study of cusp fracture in restored posterior teeth. They evaluated 39 potential risk indicators identified in previous uncontrolled studies for an association with fracture in 200 patients with fractures and 252 patients without fractures. These risk indicators delineated patients' clinical characteristics and behaviors, as well as clinical characteristics of individual teeth. The authors used logistic regression to develop models identifying risk indicators associated with fracture, both between case and control subjects and between case and comparison teeth in case subjects. RESULTS: Two risk indicators appeared in both models. The presence of a fracture line and an increase in the proportion of the volume of the natural tooth crown occupied by the restoration substantially increased the odds of fracture (P < .001). Additional risk indicators were unique to the case subject-control subject model, including subject age and other measures related to the relative size of the restoration or to loss of dentinal support. Neither patient behaviors such as clenching, grinding and biting hard objects nor occlusal characteristics such as guidance, cusp anatomy and general wear patterns were strong predictors of fracture risk. CONCLUSIONS: Among posterior teeth with restorations, two clinical features were strongly associated with the risk of cusp fracture: presence of a fracture line in the enamel and proportional volume of the restoration. CLINICAL IMPLICATIONS: Dentists assessing the risk of fracture should consider a detectable fracture line or a high ratio of restoration-to-total-crown volume as important indicators of elevated risk.

Age Factors↗