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At least 433 records · Page 24Linked to original sources

PubMed2006

Formation of a successional dental lamina in the zebrafish (Danio rerio): support for a local control of replacement tooth initiation.

In order to test whether the formation of a replacement tooth bud in a continuously replacing dentition is linked to the functional state of the tooth predecessor, I examined the timing of development of replacement teeth with respect to their functional predecessors in the pharyngeal dentition of the zebrafish. Observations based on serial semithin sections of ten specimens, ranging in age from four week old juveniles to adults, indicate that (i) a replacement tooth germ develops at the distal end of an epithelial structure, called the successional dental lamina, budding off from the crypt epithelium surrounding the erupted part of a functional tooth; (ii) there appears to be a developmental link between the eruption of a tooth and the formation of a successional dental lamina and (iii) there can be a time difference between successional lamina formation and initiation of the new tooth germ, i.e., the successional dental lamina can remain quiescent for some time. The data suggest that the formation of a successional lamina and the differentiation of a replacement tooth germ from this lamina, are two distinct phases of a process and possibly under a different control. The strong spatio-temporal coincidence of eruption of a tooth and development of a successional dental lamina is seen as evidence for a local control over tooth replacement.

Animals↗

PubMed1978

Tooth ontogeny in the upper jaw and tongue of the rainbow trout (Salmo gairdneri).

Tooth development has been studied in the upper jaw and tongue of a series of rainbow trout embryos (Salmo gairdneri). The sequence of tooth ontogeny in the maxillary bone differs significantly from that seen in the premaxillary bone. In the maxillary bone the teeth developed in an almost perfect alternating sequence from front to back, the teeth occupying the odd-numbered tooth positions developing ahead of those occupying the even-numbered tooth positions. However an alternating sequence was not encountered in the premaxillary bone of the rainbow trout where, from tooth position 4, teeth developed in sequence, and at approximately the same rate, in both directions. The significance of this difference was discussed. The teeth on the tongue developed in an alternating sequence, the fourth tooth developing first followed by the second tooth. The teeth in positions one, three and five later developed simultaneously. Evidence was presented which indicated that resorption of a tooth may commence from its pulpal surface in association with the appearance of multinucleated giant cells and not from the external surface in relation to a successional tooth. This was particularly so in the case of lingual teeth where the successor was laterally positioned or in midline teeth which lacked successional teeth.

Animals↗

PubMed2005

Tooth caries detection by curve fitting of laser-induced fluorescence emission: a comparative evaluation with reflectance spectroscopy.

BACKGROUND AND OBJECTIVES: Nitrogen laser-induced fluorescence (LIF) spectra of sound tooth consists of two broad bands centered at 440 and 490 nm, with two apparent side bands on either side. In order to locate the exact peak position of these bands and to effectively utilize the LIF spectral signatures for detection of tooth caries, the LIF spectra were curve-fitted using Gaussian spectral functions and the results were compared with those from diffuse reflectance spectral measurements. STUDY DESIGN/MATERIALS AND METHODS: The excitation light at 337.1 nm was guided to the sound and caries-affected tooth samples through the central fiber of the fiber-optic probe of a laser-induced fluorescence reflectance spectroscopy (LIFRS) system. Six surrounding fibers of the probe collect tooth fluorescence or diffuse reflectance from the lesion and direct it to a miniature spectrometer. The in vitro spectra were obtained from healthy enamel, dentin, and pulp level tooth caries. RESULTS: As compared to sound tooth, the caries tooth showed lower fluorescence and reflectance intensities in the 350-700 nm region. The deconvoluted peaks in the LIF spectra of sound tooth were found centered at 403.80, 434.20, 486.88, and 522.45 nm, whereas in the case of pulp level caries, a new peak was observed at 636.78 nm. Curve-fitted parameters, such as peak center, Gaussian curve area, full width at half intensity maximum (FWHM), and their ratios, were also found to vary with the stage of tooth caries. The ratios involving the 435 nm band, such as F405/F435, F435/F490, and F435/F525 ratios derived from curve-fitted areas and amplitudes, were found to be sensitive to discriminate between sound, dentin, and pulp level caries. Among the various diffuse reflectance spectral intensity ratios, the R500/R700 was found to be most sensitive to distinguish between pulp and dentin level caries. CONCLUSIONS: Nitrogen laser-excited fluorescence spectral studies were found to be more suited for detection of caries lesions. The LIF measurement with spectral analysis, done by curve fitting, outscores the diffuse reflectance methodology and shows the potential to screen different levels of tooth decay in a clinical setting.

Dental Caries↗

PubMed2006

Interspecific and intraspecific relationships between tooth size and jaw size in primates.

The association between mandibular robusticity, postcanine megadontia, and canine reduction in hominins has led to speculation that large and robust jaws might be required to spatially accommodate large canine and molar teeth in hominins and other primates. If so, then variations in mandibular form that are generally regarded as biomechanical adaptations to masticatory demands might instead be incidental effects of functional requirements of tooth support. While the association between large teeth and deep, robust jaws in hominins is well known, the relationship between tooth size and jaw size has not been systematically evaluated in a comparative sample of primates. We evaluate the relationships between molar tooth size, canine tooth size, and mandibular corpus and symphyseal dimensions in a sample of adult anthropoids in interspecific (n=84 species) and intraspecific (n=36 species) contexts. For intraspecific comparisons, tooth size and jaw size are correlated, but for a majority of species this is a function of sexual size dimorphism. Interspecific comparisons lend little direct support to the hypothesis that jaw breadth directly covaries with molar tooth breadth, but they do support the hypothesis that mandibular depth is associated with canine tooth size in males. The latter observation suggests that if there is a causal association between canine size and mandibular depth, it is subject to a threshold effect. In contrast, neither corpus nor symphyseal robusticity, measured as a shape index of breadth/height, are correlated with tooth size. Our results suggest that further studies of the relationship between tooth size and corpus morphology should focus on tooth root size and corpus bony architecture, and that species-specific factors should have a strong impact on such relationships.

Animals↗

PubMed2005

Cortical representation of experimental tooth pain in humans.

Cortical processing of electrically induced pain from the tooth pulp was studied in healthy volunteers with fMRI. In a first experiment, cortical representation of tooth pain was compared with that of painful mechanical stimulation to the hand. The contralateral S1 cortex was activated during painful mechanical stimulation of the hand, whereas tooth pain lead to bilateral activation of S1. The S2 and insular region were bilaterally activated by both stimuli. In S2, the center of gravity of the activation during painful mechanical stimulation was more medial/posterior compared to tooth pain. In the insular region, tooth pain induced a stronger activation of the anterior and medial parts. The posterior part of the anterior cingulate gyrus was more strongly activated by painful stimulation of the hand. Differential activations were also found in motor and frontal areas including the orbital frontal cortex where tooth pain lead to greater activations. In a second experiment, we compared the effect of weak with strong tooth pain. A significantly greater activation by more painful tooth stimuli was found in most of those areas in which tooth pain had induced more activation than hand pain. In the medial frontal and right superior frontal gyri, we found an inverse relationship between pain intensity and BOLD contrast. We concluded that tooth pain activates a cortical network which is in several respects different from that activated by painful mechanical stimulation of the hand, not only in the somatotopically organized somatosensory areas but also in parts of the 'medial' pain projection system.

Adult↗

PubMed2005

Shading of ceramic crowns using digital tooth shade matching devices.

In the 1990s, there was great optimism due to the development of devices for measuring tooth shade. The frequently not so simple, visual determination of the shade of a tooth was to be done with the aid of a device which recognizes the shade and describes it accurately by reference to a color chart. However, the skepticism towards such devices was also great. It is known that the color effect frequently differs strongly when comparing a tooth from the shade guide with a metal ceramic crown, despite identical shade designation. Anyone who considers visual shade determination to be inadequate and places his hopes in digital shade matching devices will be disappointed. It is the shade-generating structures of the metal ceramic and frequently of the veneer layers that turn out to be too thin which, despite correct shade selection, cause a different color perception. Such problems have been reduced decisively with the development of fracture-proof hard porcelain caps (Vita In-Ceram) with optical characteristics similar to teeth. In addition, the Vita System 3D-Master tooth shade system developed in 1998 by Vita in cooperation with Dr. Hall from Australia, leads the practitioner to a better understanding of the primary tooth shade characteristics of "brightness (value)", "color intensity (chroma)" and "color (wave length of the visible light, hue)". These two innovations allow a more accurate estimate of the basic shade of a natural tooth (reference tooth) and the imitation in the laboratory of its natural, shade-generating structures. If digital shade measurement supplements the visual shade estimate, then a further improvement can be expected--especially in the recognition of the basic shade. Qualitative descriptions of subjective shade measurement of a natural tooth and of its imitation in the dental laboratory by ceramics can be found frequently in professional journals and publications. With digital tooth shade matching devices, which apart from the color code of the color chart also reproduce exact, colorimetric values, such work processes can be recorded quantitatively and objectively. Reports about this type of controlled shade determination and generation are found rarely in the literature, which is surprising in view of the large number of tooth shade matching devices and dental ceramic systems available. In the present paper, the influence of the individual ceramic layers on color perception is measured and described under standardized conditions. The creation of the basic shade as it results from the composition of the various ceramic layers is traced with a spectrophotometer. The Vita In-Ceram Alumina infiltration ceramic and the VitaVM7 veneer ceramic were selected as the ceramic system. MHT-SpectroShade and Vita Easyshade were used as shade matching devices.

Aluminum Oxide↗

PubMed1983

[Response characteristics of the tooth pulp-driven neurons in the 1st somatosensory cortex, especially in the facial sensory area, of the cat].

Unit activities elicited by electrical stimulation of the tooth-pulp and tactile stimulation of the face region were recorded in the face area of the cat's first somatosensory cortex (SI). The tooth pulp driven (TPD) neurons were diffusely distributed in this area and the recording electrode encountered them at the rate of 17.3% (94/542 neurons). All of TPD neurons were also excited by non-noxious tactile stimulation of the face. Therefore, they seem to be polymodal neurons. Although mono-tooth input type neurons appeared at the rate of 15%, the majority of TPD neurons were multi-tooth input type. Many TPD neurons received inputs more dominantly from the mandibular tooth than from the maxillar one, and more dominantly from the molar tooth than from the canine tooth. Half of them received inputs only or dominantly from the contralateral tooth, whereas the incidence of the neurons receiving inputs only or dominantly from the ipsilateral tooth was only about 20%. Generally, many of the former neurons responded with short latencies, while many of the latter neurons responded with long latencies. These findings suggest that the projection pathways from the contralateral tooth to the face area of SI are different from the ipsilateral.

Animals↗

PubMed2005

[The combination of a fused tooth and a supernumerary central incisor: a possible treatment plan].

An 8-year old boy was referred to the orthodontic department because of a fused tooth. The clinical and radiological examination showed that - besides the double tooth at the region of the 21 - there was a normal tooth 22 in eruption as well. Moreover a still impacted supernumerary tooth was present in the right upper front region. The treatment included the extraction of the fused tooth and an autotransplantation of the supernumerary tooth to the extraction site of the fused tooth. During the follow-up period the pulp showed a progressive obliteration starting at the crown level with a conservation of the vitality. Apexification of the root of the transplanted tooth proceeded successfully. Furthermore a review of the literature is given in this article on the aetiology and treatment of fused teeth and on the application of autotransplantation.

Child↗

PubMed1996

Polarizing activity, Sonic hedgehog, and tooth development in embryonic and postnatal mouse.

Tooth development involves reciprocal epithelial-mesenchymal interactions, polarized growth, mesenchyme condensation, and complex morphogenetic events. Because these processes bear similarities to those occurring in the developing limb, we asked whether morphogenetic signals found in the limb also occur in the developing tooth. We grafted mouse embryo tooth germs to the anterior margin of host chick embryo wing buds and determined whether the dental tissues had polarizing activity. Indeed, the grafts induced supernumerary digits. Activity of both molar and incisor tooth germs increased from bud to cap stages and was maximal at late bell stage in newborn. With further development the polarizing activity began to decrease, became undetectable in adult molar mesenchyme but persisted in incisor mesenchyme, correlating with the fact that incisors grow throughout postnatal life while molars do not. When different portions of neonatal incisors were assayed, a clear proximo-distal gradient of activity was apparent, with maximal activity restricted to the most proximal portion where undifferentiated mesenchyme and enamel organ reside. In situ hybridizations demonstrated that prior to induction of supernumerary digits, the tooth germ grafts induced expression in host tissue of Hoxd-12 and Hoxd-13. In addition, whole-mount in situ hybridizations and immunohistochemistry showed that developing tooth germs express Sonic hedgehog (Shh). Shh expression was first detected in bud stage tooth germs; at later stages Shh transcripts were prominent in enamel knot and differentiating ameloblasts at the cuspal region. We concluded that tooth germs possess polarizing activity and produce polarizing factors such as Shh. As in the limb, these factor(s) and activity probably play key roles in establishing polarity and regulating morphogenesis during early tooth development. Given its subsequent association with differentiating ameloblasts, Shh probably participates also in cytogenetic events during odontogenesis.

Aging↗

PubMed1998

Expression and function of FGFs-4, -8, and -9 suggest functional redundancy and repetitive use as epithelial signals during tooth morphogenesis.

To elucidate the roles of fibroblast growth factors (FGF) in the regulation of tooth morphogenesis we have analyzed the expression patterns of Fgf-4, -8, and -9 in the developing mouse molar and incisor tooth germs from initiation to completion of morphogenesis by in situ hybridization analysis. The expression of these Fgfs was confined to dental epithelial cells at stages when epithelial-mesenchymal signaling regulates critical steps of tooth morphogenesis. Fgf-8 and Fgf-9 mRNAs were present in the oral epithelium of the first branchial arch at E10 and 1 day later expression became more restricted to the area of presumptive dental epithelium and persisted there until the start of epithelial budding. Fgf-8 mRNAs were not detected later in the developing tooth. Fgf-4 and Fgf-9 expression was upregulated in the primary enamel knot, which is a putative signaling center regulating tooth shape. Subsequently, Fgf-4 and Fgf-9 were expressed in the secondary enamel knots at the sites of tooth cusps. Fgf-9 expression spread from the primary enamel knot within the inner enamel epithelium where it remained until E18. In the continuously growing incisors Fgf-9 expression persisted in the epithelium of the cervical loops. The effects of FGFs were analyzed on the expression of the homeobox-containing transcription factors Msx-1 and Msx-2, which are associated with tissue interactions and regulated by the dental epithelium. Locally applied FGF-4, -8, and -9 stimulated intensely the expression of Msx-1 but not Msx-2 in the isolated dental mesenchyme. We suggest that the three FGFs act as epithelial signals mediating inductive interactions between dental epithelium and mesenchyme during several successive stages of tooth formation. This data suggest roles for FGF-8 and FGF-9 during initiation of tooth development, and for FGF-4 and FGF-9 during regulation of tooth shape. FGF-9 may also be involved in differentiation of odontoblasts. The coexpression of Fgfs with other signaling molecules including Shh and several Bmps and their partly similar effects suggest that the FGFs participate in the signaling networks during odontogenesis.

Animals↗

PubMed2002

Changes in tooth position in humans in relation to arterial blood pressure.

The three-dimensional physiological tooth movement synchronized with the heartbeat is called periodontal pulsation. This study utilized a computer-assisted amorphous sensor to evaluate the relation between tooth position and arterial blood pressure, and also between the amplitude of periodontal pulsation and arterial blood pressure. The measuring device consisted of a small magnet attached to the tooth and an amorphous sensor that was used to detect displacement of the tooth without actually contacting it. The sample consisted of the upper left central incisors of six healthy Japanese volunteers. The three measuring points for each tooth were on the labial surface. The cold-pressor test was used as an autonomic nerve stimulus that induces an increase in blood pressure and heart rate. Periodontal pulsation, electrocardiogram, blood pressure and heart rate were recorded simultaneously during a 1 min pre-test relaxation, a 2 min cold-pressor test and a 1 min recovery. The results showed significant correlations between tooth position and mean blood pressure in five of the six volunteers and between tooth position and pulse pressure in four. Moreover, it was confirmed that tooth position shifted in the labial direction in conjunction with an increase of the mean blood pressure induced by cold stimulation. Significant correlations were found between the amplitude of periodontal pulsation and pulse pressure in four of the volunteers. These findings suggest that in humans tooth position might be affected by the force of blood pressure transmitted through periodontal vessels and that the amplitude of periodontal pulsation tends to reflect changes of pulse pressure rather than changes in mean blood pressure.

Adult↗

PubMed1989

Reduction in tooth stiffness as a result of endodontic and restorative procedures.

Endodontically treated teeth are thought to be more susceptible to fracture as a result of the loss of tooth vitality and tooth structure. This study was designed to compare the contributions of endodontic and restorative procedures to the loss of strength by using nondestructive occlusal loading on extracted intact, maxillary, second bicuspids. An encapsulated strain gauge was bonded on enamel just above the cementoenamel junction on both the buccal and lingual surfaces, and the teeth were mounted in nylon rings leaving 2 mm of root surface exposed. Under load control, each tooth was loaded at a rate of 37 N per s for 3 s and unloaded at the same rate in a closed loop servo-hydraulic system to measure stiffness. A stress-strain curve was generated from each gauge prior to alteration of the tooth and after each procedure performed on the tooth. Cuspal stiffness, as a measure of tooth strength, was evaluated on one of two series of sequentially performed procedures: 1. (a) unaltered tooth, (b) access preparation, (c) instrumentation, (d) obturation, and (e) MOD cavity preparation; or 2. (a) unaltered tooth, (b) occlusal cavity preparation, (c) two-surface cavity preparation, (d) MOD cavity preparation, (e) access, (f) instrumentation, and (g) obturation. Results on 42 teeth indicate that endodontic procedures have only a small effect on the tooth, reducing the relative stiffness by 5%. This was less than that of an occlusal cavity preparation (20%). The largest losses in stiffness were related to the loss of marginal ridge integrity. MOD cavity preparation resulted in an average of a 63% loss in relative cuspal stiffness.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed2000

The effect of tooth size discrepancy on occlusion: An experimental study.

The purposes of this experimental study are the following: (1) to compare the anterior and overall tooth size ratios reported by Bolton to values reported in epidemiologic studies, (2) to assess the accuracy of tooth size discrepancy measurements, (3) to investigate to what extent generalized tooth size discrepancy affects occlusion, (4) to investigate the effect of leveling the curve of Spee, and (5) to evaluate the effect of extraction therapy of 4 premolars on occlusion. For the first part of the study, Bolton's mean anterior and overall tooth size ratio (as well as the extraction values) were compared with calculations derived from 4 publications reporting mean mesiodistal tooth width by using the t test (P </=.05). The second part of the study was carried out on a setup made from 1 dental cast of a male patient judged to have an ideal occlusion at the end of a nonextraction treatment. Our data reveal (1) no significant difference between the overall tooth size ratios of the Bolton values compared to 4 studies, but the anterior ratios were significantly different, (2) high reproducibility (99%) of tooth size discrepancy measurements, (3) that severe tooth size discrepancy affects the occlusion only a little, (4) that an excessive (6 mm) curve of Spee creates the poorest setup result, and (5) that extraction therapy only slightly affected the final occlusion. The effect of generalized tooth size discrepancy appears to be limited.

Dental Occlusion↗

PubMed2006

Effect of dental practice characteristics on racial disparities in patient-specific tooth loss.

OBJECTIVE: The objective of this study was to test the hypothesis that dental practice characteristics are associated with tooth loss incidence with both tooth-specific and patient-specific characteristics already taken into account. RESEARCH DESIGN: A population-based prospective cohort study was conducted. In-person interviews and clinical examinations were done at baseline, 24, and 48 months, with telephone interviews every 6 months. Practices that coincidentally served participants in the study completed practice characteristics questionnaires. To increase inferential power when testing practice-level effects, detailed tooth-specific and patient-specific data were simultaneously taken into account in tests for association between practice-level effects and tooth loss. SETTING: Data were from the Florida Dental Care Study. The key health outcome was tooth loss, a leading measure of a population's oral health. PARTICIPANTS: Eight hundred seventy-three African-Americans and non-Hispanic whites who had at least 1 tooth. RESULTS: Certain practice characteristics were associated with tooth loss, including the racial mix of the practice's patient population; persons who attended practices with higher percentages of African-Americans were more likely to receive a dental extraction regardless of the individual patient's race. CONCLUSIONS: This is the first longitudinal report of increased risk for tooth loss resulting from practice-level effects. Although a patient-level racial disparity remained evident, and even with detailed tooth-specific and patient-level characteristics taken into account, racial differences in characteristics of practices attended independently contributed to the patient-level racial disparity in health.

Black or African American↗

PubMed2006

Pattern of tooth loss in an elderly population from Ibadan, Nigeria.

OBJECTIVES: To determine tooth loss, edentulousness, causes of tooth loss and pattern of tooth loss in the elderly in South East Local Government area (SELGA) in Ibadan. BACKGROUND DATA: SELGA is one of the largest in Oyo State, Nigeria and has a population of 225,800. DESIGN: A cross-sectional survey. METHODOLOGY: A total of 690 elderly individuals who were 65 years and above living in various wards in SELGA were interviewed by two interviewers and examined by two trained and calibrated examiners whilst two record clerks recorded all the findings of the examination. RESULT: Forty-eight per cent of the subjects in the study had not lost any teeth. The mean tooth loss was 4.5+/-7.6. Percentage edentulousness was 1.3% and this was higher in males than in females. This difference was not statistically significant (chi(2)=0.07 p=0.7). The total number of teeth lost was 3,102, 14% of the total number of teeth examined. The study showed that caries was not a major cause of tooth loss. Only 22 (0.7%) teeth were lost as a result of caries, 19 (0.6%) were lost because of trauma and periodontal disease contributed to loss of 3,061 (98.7%) teeth. Mandibular teeth exhibited a higher rate of retention than maxillary teeth. The percentage of elderly individuals with tooth loss increased with age. CONCLUSION: The study highlights the high life expectancy of a tooth among the elderly in SELGA. Despite the different cause of tooth loss in this area, in comparison with developed countries, the pattern of tooth retention appeared similar.

Age Factors↗

PubMed1992

Measurements of tooth length in panoramic radiographs. 2: Observer performance.

Observer performance in tooth-length measurements in panoramic radiography has been examined. Sixty-four teeth, evenly distributed between maxillary first molars, second premolars and mandibular first and second premolars, were fixed in plastic moulds. Each cast was radiographed with an Orthopantomograph, twice with steel balls indicating the cusps and apices of the teeth and once without them. One observer measured the radiographic tooth length twice in both radiographs with indicators in order to estimate the true radiographic tooth length and the repositioning error, and twice in the radiographs without indicators. Seven other observers measured the tooth length on the radiographs without indicators, twice applying their own criteria and twice using defined criteria. The accuracy of the tooth-length measurements was calculated by comparing the true radiographic tooth length with the measurements of the seven observers. The intra-observer variation was defined as the difference between two measurements on the same radiograph. The accuracy and the precision of the tooth-length measurements were highly influenced by the observer performance. The mean radiographic tooth length of the seven observers was closer to the true radiographic tooth length when the observers applied the defined criteria. The inter- and intra-observer variation was higher for the measurements of the maxillary teeth (0.3-1.9 mm) compared with the mandibular teeth (0.3-0.9 mm) for most observers. The highest intra-observer variation was found for the palatal root of the maxillary first molar. The intra-observer variation of four observers decreased somewhat when the defined criteria were used; for the other three observers, however, the variation increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗

PubMed2004

The effect of birthweight on tooth-size variability in twins.

Studies indicate that low birthweight (LBW) children display reduced deciduous tooth size but there is little information about permanent tooth size. It has also been shown that dental fluctuating asymmetry (FA) increases in response to various environmental influences, but the relationship between birthweight and FA remains unclear. The aim of this study was to compare tooth size and asymmetry, according to birthweight, in the deciduous and permanent dentitions of a sample of Australian twins. The study sample comprised 436 twins, classified into 2 groups: normal birthweight (NBW > 2500 g) and low birthweight (LBW < or = 2500 g). For each individual it was generally possible to measure maximum mesiodistal crown diameters of both deciduous and permanent central incisors from serial dental models. Correlations were calculated between tooth-size variables and birthweight; subsequently comparisons of tooth size and FA were made between the LBW and NBW samples using Student's t tests. Small positive correlations (around .1) were noted between birthweight and tooth-size variables. There was no evidence of tooth-size reduction in the LBW male sample, but the LBW females displayed tooth-size reduction of approximately 2-3% for both deciduous and permanent incisors, compared to the NBW females. There was no evidence of increased FA in the LBW individuals of either sex. These findings indicate that developing teeth are generally well-protected from developmental disturbances during prenatal and perinatal periods. Further research is needed to clarify the biological basis of an apparently true but weak association between tooth size and birthweight.

Birth Weight↗

PubMed2004

[Influence of occlusal contacts on tooth displacement for mesio-distal direction].

To fabricate a prosthesis which is functionally harmonized with the stomatognathic system, the interocclusal relationship must be reproduced as accurately as possible. This study investigated the influence of the occlusal contacts upon tooth displacement and clarified the optimal occlusal contacts for the prosthesis. The displacement paths of six maxillary left first molars of six adults in good general health were measured in this study. We gave each test tooth eight patterns of artificial occlusal contacts by attaching platinum foil on the occlusal surface. Subjects were asked to perform clenching at the intercuspal position (= ICP) with medium occlusal forces, and 3-dimensional tooth displacement paths were measured by the Type M-3 tooth displacement transducer. The following conclusions were obtained. 1. Using the Student's t-test for statistical analysis, it was suggested that the difference of the buccolingual location of occlusal contacts influenced the direction of the tooth displacement. 2. The tooth which had occlusal contact in the buccal cusp displaced in the mesio-buccal direction, so this may create a wide dental arch and a slight discrepancy was generated at the distal interproximal contact area of the tooth. 3. It was shown that the tooth which had occlusal contact in the buccal cusp rotated in the buccoapical direction in reverse to the natural tooth.

Adult↗