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PubMed1993

On tooth movement.

Current concepts of clinical orthodontic tooth movement are misleading. Traditionally, these have been described as dependent on force levels and being tipping/bodily in nature. The following is a reevaluation of the relationships between tooth movement and orthodontic mechanotherapy not usually considered when analyzing tooth movement clinically. It is our contention that confusion as to the biological response(s) to mechanical force is derived from in vivo orthodontic trials where conditions are undefined. This correlates with variable biological responses within the periodontium. Constantly changing moment to force ratios inherent to the dynamic load deflection rates of any system used to move a tooth cause changing tendencies for crown/root tipping. This implies that the accepted notion of static translatory tooth movement, although a useful didactic concept, is currently unattainable. In actuality, it has never been documented empirically using any conventional orthodontic appliance.

Biomechanical Phenomena↗

PubMed2001

Growth hormone receptor and IGF-I receptor immunoreactivity during orthodontic tooth movement in the prednisolone-treated rat.

Bone remodeling during tooth movement is regulated by local and systemic factors. Two regulators of bone metabolism are growth hormone (GH) and insulin-like growth factor-I (IGF-I). Their effects are mediated via binding to GH receptor (GHR) and IGF-I receptor (IGF-IR) in target tissues. Corticosteroids may affect the activity of these growth factors. This study examined the effect of prednisolone on GHR and IGF-IR expression in dental tissues following orthodontic tooth movement. The corticosteroid-treated group (N = 6) was administered prednisolone (1 mg/kg) daily and the control group (N = 6) received equivalent volumes of saline. An orthodontic force (30 g) was applied to the maxillary first molar. Animals were sacrificed 12 days postappliance insertion. Sagittal sections of the first molar were stained for GHR and IGF-IR immunoreactivity. GHR and IGF-IR cell counts were elevated following appliance-treatment. Orthodontic tooth movement appeared to up-regulate GHR and IGF-IR immunoreactivity, but this up-regulation was reduced following prednisolone treatment. The suppression of GHR and IGF-I immunoreactivity in steroid-treated animals infers the mechanism whereby bone resorption and deposition, necessary for orthodontic tooth movement, may be inhibited by prednisolone. However, at 12 days postappliance insertion, no difference in orthodontic tooth movement was observed following low-dose prednisolone treatment.

Alveolar Process↗

PubMed2001

Tooth size and morphology in twins.

OBJECTIVE: To assess concordance of tooth size and occlusal morphology in monozygotic (identical) and dizygotic (non-identical) twins compared to unrelated controls in order to determine how much these dental traits are related to inheritance. METHODS: Mesiodistal and bucco-lingual dimensions of tooth size in 34 pairs of twins were measured with dial calipers. In addition, the occlusal morphology of nine pairs of teeth was assessed using a co-ordinate measuring machine with a non-contact laser probe. RESULTS: The results showed greater concordance in tooth size for both mesiodistal and bucco-lingual dimensions within twin pairs compared to twin and unrelated controls. Furthermore, monozygotic (MZ) twins showed greater concordance than dizygotic (DZ) twins for all permanent teeth with statistically significant variance for the mesiodistal dimension (P = 0.01) but not bucco-lingual dimension. Superimposed computer models of the digitized occlusal surfaces showed a high degree of similarity for MZ twins compared to DZ twins. The mean intrapair deviation was 147 microm for MZ, 209 microm for DZ and 258 microm for unrelated controls. CONCLUSIONS: The remarkable similarity in the tooth size and morphology of monozygotic twins suggests a strong inheritability factor to tooth size and shape and that these may be useful as additional tools for zygosity determination along with other dental traits.

Adolescent↗

PubMed2002

Measurement of strain on tooth roots during post removal with the Eggler post remover.

AIM: The aim was to measure root surface strains in teeth when removing cast post/cores with the Eggler post remover. METHODOLOGY: Two groups of 10 teeth each were tested: group 1 had 1 mm thickness of dentine coronally, and group 2 had 2 mm thickness of dentine. After root filling, 10 mm long cast post/cores were constructed and cemented with zinc phosphate cement, and strain gauges were applied to the roots. The post/cores were removed with the Eggler post remover whilst strain measurements were being recorded. Posts were removed twice: initially along the long axis of the tooth and then at a 10 degrees angle to the long axis. Comparisons between groups 1 and 2 were analysed statistically with the Mann-Whitney U-test whilst strains within each group were analysed with the Wilcoxon Signed Rank test at the 95% level of confidence. RESULTS: There was no significant difference in the strains measured between groups 1 and 2, and no significant difference within each group when removing posts along the long axis of the tooth and at a 10 degrees angle. Three teeth in group 1 and one tooth in group 2 fractured when removing posts at the 10 degrees angle. Three fractures were small slivers of dentine at the point where the Eggler's repeller arms contacted the tooth mesially and distally, whilst one tooth (from group 1) fractured obliquely. CONCLUSIONS: Post removal with the Eggler device is a relatively safe procedure but care must be taken when there is a possibility of pulling the post out in a nonaxial direction or when less than 1 mm of dentine surrounds the apical end of the post.

Cementation↗

PubMed2002

Associated factors of tooth wear in southern Thailand.

The purpose of this study was to evaluate the possible risk factors connected with tooth wear. Using the Tooth Wear Index (TWI) and the charting of pre-disposing factors tooth surface loss was recorded in 506 patients, of the Dental Hospital, Prince of Songkla University. We found that age, sex, number of tooth loss, frequency of alcohol, sour fruit and carbonate intake were significant risk factors. Regarding the tooth position, the first molar showed the greatest degree of wear, while the canine and premolar showed the least, respectively. The occlusal surface showed the greatest wear and the cervical, lingual and buccal surfaces showed the least, respectively.

Adult↗

PubMed2002

The effect of functional occlusal forces on orthodontic tooth movement and tissue recovery in rats.

The influence of physiologic occlusal forces on tissue response to orthodontic tooth movement and its subsequent recovery was investigated in rats. The mandibular incisors were subjected to tipping and intrusive loads for 2 weeks. In 27 animals, the teeth remained in occlusion, while the incisors were shortened out of occlusion in 29. In each group, some rats were killed at the end of the tooth movement process, and the rest were kept alive for a 13-week recovery period. The subgroups were matched with corresponding controls. Tooth intrusion and eruption were monitored throughout the experiment; then histomorphometric and histopathologic evaluations were performed on the incisors and their periodontal tissues. Tooth movement was barely affected by the functional forces. However, immediately upon 2-week load application, damage to the pulp was more extensive in the occluding teeth; this might be due to the combined intrusive vectors of functional and mechanical loads. The effect of the physiologic function was expressed primarily during the recovery period, in which the eruptive function and distorted periodontal ligament space returned to normal significantly faster in the occluding teeth. This was also true for the healing of dental and periodontal lesions. The incidence of tooth resorption was also reduced. Normal occlusal function is imperative for rapid reconstitution of the damage caused by orthodontic forces.

Animals↗

PubMed2002

Proliferating cell nuclear antigen (PCNA) expression in tooth primordia in the field vole (Microtus agrestis, Rodentia).

Cell proliferation in developing tooth germs has been studied particularly using bromodeoxyuridine (BrdU) incorporation into growing tooth primordia and by counting and three-dimensional (3D) reconstruction of mitoses in serial sections of developing teeth. PCNA has been proposed as an alternative marker of proliferation activity. The aim of our study was to detect immunohistochemically locations of PCNA-positive cells in developing tooth germs of Microtus agrestis (Rodentia). PCNA expression could be distinguished in oral epithelium and mesenchyme before first signs of dental lamina elevation. During bud, cap, and bell stages, positive immunostaining could be observed at defined sites in enamel organ, tooth papilla, and dental follicle. Rudimental tooth germs of the upper diastema, enamel knots, and inner enamel epithelium at day of ontogeny 18 and 19 showed negative reaction. PCNA marks cycling and early G0 cells and can be used successfully as a proliferation marker even in collection material.

Animals↗

PubMed2005

Soluble cytokine receptor treatment in experimental orthodontic tooth movement in the rat.

Pro-inflammatory cytokines, such as interleukin-1 (IL-1) and tumour necrosis factor-alpha (TNF-alpha), are believed to play a role in the biological processes involved in the course of orthodontic tooth movement and especially in root resorption. The inhibition of cytokine activity, e.g. by soluble receptors, could be beneficial in reducing this unwanted side-effect. The aim of this study was to investigate the role of cytokines IL-1 and TNF-alpha in the course of experimentally induced tooth movement. The upper left first molar was moved orthodontically in 80 male Wistar rats using a coil spring with a force of 0.5 N. Starting at day -1, three groups of 20 animals each received daily intraperitoneal injections (ip) of 2 ml of 1 mug/ml soluble receptors (a) to IL-1(sIL-RII), (b) to TNF-alpha (sTNF-alpha-RI) and (c) a combination of (a) and (b). Twenty animals served as the control. After 3, 6, 9 and 12 days, the animals were killed in groups of five. The amount of tooth movement was registered and the maxillae were prepared for histological and histomorphometric analysis. Osteoclasts and odontoclasts were identified using tartrate-resistant acid phosphatase (TRAP) histochemistry. The amount of tooth movement was reduced in all receptor-treated groups by approximately 50 per cent. At the same time, the number of TRAP-positive cells on the desmodontal bone surface and on the surface of the roots was reduced. Thus, systemic application of soluble receptors to IL-1 and TNF-alpha following experimental induction of tooth movement in the rat reduced the number of osteoclasts as well as odontoclasts.

Acid Phosphatase↗

PubMed2003

Possible role of immunocompetent cells and the expression of heat shock protein-25 in the process of pulpal regeneration after tooth injury in rat molars.

Recent studies have established that heat shock proteins (HSPs) potentially play a role in immunosurveillance. The purpose of the present study was to clarify the relationship between the chronological changes of immunocompetent cells and the expression of HSP-25 in the process of pulpal regeneration after tooth injury in rat molars by immunocytochemistry for HSP-25 and class II major histocompatibility complex (MHC) antigen. In untreated control teeth, intense HSP-25 immunoreactivity was found in the cell bodies of odontoblasts. Both cavity preparation and tooth replantation caused the degeneration of the odontoblast layer to result in the loss of HSP-25 immunoreactions in the suffered dental pulp at the early stages after tooth injury. Numerous class II MHC-positive cells appeared along the pulp-dentin border and extended their cell processes into the dentinal tubules at 12-24 h after cavity preparation and 3 days after tooth replantation. Newly differentiated odontoblast-like cells with HSP-25 immunoreactivity were arranged at the pulp-dentin border and the class II MHC-positive cells retreated towards the subodontoblastic layer by post-operative days 3-5 after tooth injury. Thus, the common cellular events occur during pulpal regeneration following two different experimental injuries. These findings indicate that the time course of changes in the expression of HSP-25 immunoreactivity reflects the degeneration/regeneration process of odontoblasts and that the temporal appearance of the class II MHC-positive cells at the pulp-dentin border suggests their participation in odontoblast differentiation as well as in initial defence reactions during the pulpal regeneration process.

Animals↗

PubMed1992

Missing primary teeth due to tooth bud extraction in a remote village in Tanzania.

The practice by traditional healers of extracting tooth buds as a cure for diarrhoea and fevers in children has existed in Tanzania for many years, but its extent is not known. This paper reports on the prevalence of missing primary teeth due to this practice among children living in Manghweta, a remote village in Tanzania. All children (n = 262) aged 5 years and below were examined for missing primary teeth. Only cases in which mothers confirmed that tooth bud extraction had been performed were recorded. Tooth buds had been extracted from 37.4% of the children. The majority of extractions (60.5%) were from the lower jaw, and almost all (99.4%) were canines. Tooth bud extraction was always bilateral. It is concluded that the practice of extracting tooth buds as a cure for diarrhoea and fevers in children still exists in Tanzania.

Child, Preschool↗

PubMed1996

Ultrasonic determination of gingival thickness. Subject variation and influence of tooth type and clinical features.

The objectives of the present study were (I) to determine the validity and reliability of measuring gingival thickness (GTH) with a recently developed, commercially available ultrasonic device; (II) to measure GTH in relation to tooth type and age of proband; (III) to correlate GTH with varying forms of premolars, canines and incisors. Ultrasonic measurements were performed in 200 periodontally healthy, male probands representing 3 different age groups (20-25, 40-45, 55-60 years). In the maxilla, mean GTH varied between 0.9 mm (canines, 1st molars) and 1.3 mm (2nd molars). In the mandible respective mean values ranged between 0.8 mm (canines) and 1.5 mm (2nd molars). No differences in means and standard deviations (0.36-0.39 mm) were observed in different age groups. In order to correlate GTH with other clinical parameters and form of tooth, in 42 probands of the youngest age group, presenting with no attrition or abrasion, no artificial crown restorations and (following prophylaxis) no overt gingivitis and no periodontal probing depth in excess of 3 mm, detailed clinical measurements and stone model cast analyses were performed. By stepwise multiple linear regression analysis, 24% (p < 0.0001) of the variation of GTH was explained by probing depth, recession, width of gingiva and tooth type. The ratio of the width of the crown to its length was not included into the model. When performing analysis of covariance with the subject as factor, the model was improved, now explaining 41% of the variation of GTH. In this model, the influence of periodontal probing depth was decreased, and recession was not included. It was concluded that there are individual differences in GTH (i.e., different biotypes). However, thickness mainly depends on tooth type and is correlated with width of gingiva. There appears to be no association with shape and form of the tooth. Validity and reliability of measuring GTH with the ultrasonic device was found to be excellent.

Adult↗

PubMed1986

Radiographic study of alveolar bone height related to tooth and root length.

In radiographs from 76 randomly selected periodontally healthy subjects, aged 18-22 yr, at the School of Dentistry in Stockholm, the alveolar bone height was evaluated and correlated to the root length as well as to the entire tooth length. The root lengths were also related to the entire tooth lengths. The mean tooth length was found to be 24.9 mm and the mean root length 65.7% of the mean tooth length. The correlation of alveolar bone height to the root length varied between 91.5% and 96.3% and the correlation to the entire tooth length between 54.0 and 65.7%.

Adolescent↗

PubMed1993

Reasons for tooth extraction in the western states of Germany.

The purpose of this study was to collect information on the main causes of tooth loss in the western states of Germany as perceived by dentists and their patients. Sixty-eight dentists, out of 80 that were selected with a systematic random method for an epidemiological study in the western states of Germany, recorded their reason for tooth extraction. Included in the study were only extractions of permanent teeth during a period of 2 weeks (March 1990), up to a maximum of 20 patients per dentist. Of 926 returned questionnaires, 882 could be evaluated. In all 1215 teeth in 882 patients were extracted. The extraction of third molars was included as a reason, when caries, periodontal reasons and others were not indicated. Caries was the reason given for 20.7% of all extractions; periodontal diseases for 27.3%; caries and periodontal reasons for 18.7%; third molars for 14.7%; prosthetic reasons for 11.2%; orthodontic reasons for 4.1%; trauma for 0.4% and others for 2.9%. While caries is a major reason in all age groups, periodontal diseases and the combination of caries and periodontal reasons are more frequent than all other reasons for the age groups beyond 40 or 45 yr, respectively. The third molar was the most often extracted tooth. The patients were asked for their main reason for tooth extraction. For the patients, pain was the major reason for extraction (47.2%). According to the participating dentists periodontal disease is the most frequent cause of tooth extraction for people over 40 yr of age, while for those below 40 yr of age, caries and third molar extractions are the most frequent reasons.

Adolescent↗

PubMed1999

Development of transplanted pulp tissue containing epithelial sheath into a tooth-like structure.

The aim of these studies was to find out whether intact neonatal pulp tissue containing residual epithelial cells can induce the development of a tooth-like structure in situ. First maxillary neonatal hamster molar pulps containing adhering undifferentiated epithelial cells were transplanted submucosally in the oral cavity of recipient mothers for periods ranging from 2-8 weeks and the tissues were then processed for light microscopy. Developing tooth-like structures containing mineralised tubular dentine, predentine and a vascularised pulp-like chamber lined with functional odontoblast-like cells were observed in the specimens within 2 weeks of transplantation. Enamel and root formation were not observed. These data indicate that neonatal dental pulp tissues containing epithelial cell remnants have the capacity to develop into tooth-like structures and that this could be the explanation for the development of tooth-like structures sometimes observed in infants after extraction of a natal tooth.

Amelogenesis↗

PubMed1998

Degeneration of tooth germ in the developing dentition of the gray short-tailed opossum (Monodelphis domestica).

The aim of this study was to examine the developmental aspects of the dental lamina and the tooth germ of the marsupial opossum (Monodelphis domestica), and to clarify the dental formula of this animal. Specimens were 12-, 16-, and 18-d-old opossums. 3-D reconstructions were constructed from frontal serial sections. In these animals, the tooth germs of the deciduous maxillary and mandibular canine, deciduous third premolar and first molar, and the deciduous maxillary first incisor and second molar had a successional dental lamina and a replacement tooth germ. The tooth germ of the deciduous maxillary fourth incisor and the mandibular first incisor were reduced. The dental lamina was continuous in each jaw except for the deciduous maxillary first incisor. The first dentition (deciduous dentition) remained as the permanent dentition on the deciduous maxillary first incisor, and the deciduous maxillary and mandibular canine and first molar. The maxillary fourth incisor and the mandibular first incisor were the second dentition (successional dentition). Only the deciduous third premolars were replaced. These results showed monophyodonty caused by both deciduous and replacement tooth germ degeneration.

Animals↗

PubMed1992

Reasons for and incidence of tooth mortality in a Swedish population.

Longitudinal studies on tooth mortality are rare but the reasons for tooth mortality have been studied by several authors. The aims of this investigation were to study the reasons for and incidence of tooth mortality in an earlier described Swedish population of 200 patients on two occasions with an interval of 5-7 years, and to see if the reasons for extractions were correlated to posts, crowns or endodontic status, respectively. 197 (4.0%) of the 4889 teeth registered at the first examination were lost during the interval. 65 (33%) of the lost teeth were endodontically treated. 44 (68%) of these were registered as having one or more root with a root-filling ending more than 2 mm from the apex and 29 (45%) were judged to have an improper seal. In 93 of the 197 lost teeth it was possible to find the reason for extraction from the patient chart. Based on distribution of selected variables, these 93 teeth seemed to be representative of the whole group of 197. It was concluded that tooth losses were evenly distributed in the different age-groups and that above all molars but also premolars were lost more often than teeth in the frontal region. Furthermore, endodontically treated teeth were lost more often than other teeth and the quality of the root-filling affected the risk for losses while crowned teeth did not run a higher risk of being lost than teeth without crowns. Finally, it was found that caries, including pulpitis and apical periodontitis, was the main reason for tooth extractions.

Adult↗

PubMed2002

Greening of the tooth-amalgam interface during extended 10% carbamide peroxide bleaching of tetracycline-stained teeth: a case report.

UNLABELLED: At-home bleaching with 10% carbamide peroxide in a custom-fitted tray has been shown to have some minor effects on certain brands of amalgam, pertaining to mercury release, but generally, effects on amalgam are not considered clinically significant. However, in this case report, a greening of the tooth structure in certain areas immediately adjacent to amalgam restorations in the maxillary and mandibular first molars occurred during tooth whitening. Other amalgam restorations in mandibular and maxillary second molars in the same mouth did not demonstrate any green discoloration of the teeth. Upon removal of the affected amalgam restorations, recurrent decay was present in the areas of tooth greening but not in other areas adjacent to the restoration. The teeth were restored with posterior composite restorations. Whether the green discoloration was a result of some loss of material from a particular brand of amalgam, indicating leakage, or indicative of original or recurrent tooth decay is unclear in this single-patient situation. Other patients in the same study did not demonstrate this occurrence. Dentists should be ready to replace amalgam restorations should this green discoloration in adjacent tooth structure occur during bleaching, in case decay is present. CLINICAL SIGNIFICANCE: The unusual discoloration cited suggests that amalgam restorations in potentially esthetic areas, including the lingual of anterior teeth, should be replaced prior to bleaching, to avoid the problem of difficult stain removal or translucency allowing restoration visibility following bleaching.

Adult↗

PubMed1998

Dental erosion and bruxism. A tooth wear analysis from south east Queensland.

Tooth-tissue loss from erosion and attrition from bruxism were associated findings in 104 patients with excessive toothwear from South East Queensland. Approximately one-third of these subjects had been given a diagnosis of bruxism prior to referral. After a structured interview and clinical examination, the prevailing diagnosis was tooth erosion associated with occupational or sports-related dehydration, and one-third of the subjects were provisionally classified as bruxers. Eight items of clinical history and examination, designed to differentiate bruxers from non-bruxers, were analysed retrospectively from their records. These clinical items, by which the diagnosis of bruxism might be made, segregated the subjects into three groups of equal size, 'bruxers, possible bruxers and non-bruxers,' by a notional score for bruxism. The presence of occlusal attrition or erosion on the sextants of the dentitions was determined by scanning electron microscopic criteria on epoxy resin dental casts. The incidence of attrition versus erosion was compared between the three groups. The hypothesis was that attrition would be found on more sextants of bruxers than non-bruxers. Erosion predominated in virtually all sextants in all three groups, to the virtual exclusion of attrition in the molar sextants. The exception was the mandibular anterior sextant, where more sextants in bruxers were affected by attrition. Thus extrinsic or intrinsic acid erosion was strongly associated with occlusal tooth wear found in bruxers. Conversely, tooth-wear patterns were unreliable indicators of a bruxing habit, for attrition alone was often found on acid-exposed teeth. Thus, even if a patient is suspected of having bruxism, dental erosion is more likely the cause of tooth-tissue loss than attrition, especially in the dehydrating environment of South East Queensland.

Adult↗