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PubMed2005

Factors associated with implant recommendation for single-tooth replacement.

The use of dental implants for single-tooth replacement has been established as a predictable treatment option; yet, limited data are available as to how frequently this option is recommended to patients. The aim of the present study was to examine the frequency of implant recommendation by general dental practitioners after single-tooth extraction and factors influencing their decision to recommend an implant. All single-tooth extractions performed in 26 general dental practice clinics in Kuwait over a 30-day period were examined. Dentists in these centers used the study form to record demographic data, the type of tooth extracted, reason for extraction, and replacement options presented to the patients. Univariate and logistic regression analyses were used to examine associations between background factors and decisions to recommend implant therapy. A total of 1367 patients (mean age, 37.9 +/- 11.8 years) had an extraction of one tooth during the study period. Forty-three patients were offered implants as a replacement option (3.3% of the total sample; 8.6% of patients who were offered tooth replacement options). Factors associated significantly with the recommendation of an implant by Kuwaiti dentists to their patients included younger age, regular dental maintenance visits, and adequate oral hygiene practices (P < 0.05; binary logistic regression). Dental implant recommendation for single-tooth replacement in the present sample of dentists was low. Factors associated significantly with dentist recommendation of an implant for single-tooth replacement included age, history of dental maintenance, and oral hygiene practices.

Adolescent↗

PubMed2006

Cell proliferation in teeth reconstructed from dispersed cells of embryonic tooth germs in a three-dimensional scaffold.

Tissue engineering can now reproduce tooth from postnatal tooth cells. However, crown formation is not accurately reconstituted, even when the complex structure of the enamel dentin is reproduced. Here, we showed that a tissue-engineered (TE) tooth, exhibiting morphogenesis according to regular crown-cusp pattern formation, was produced by embryonic tooth germ cells in a three-dimensional scaffold. Heterogeneous cells dissociated from embryonic day 14 (E14) mice tooth germs were seeded on a scaffold and implanted under a kidney capsule in adult mice. The developmental process of the implants was examined for up to 14 d. At 5 d, the cells had formed initial tooth germ, followed by enamel-covered dentin tissue formed symmetrically. To study the developmental process, we examined the growth pattern using 5-bromo-2'-deoxyuridine (BrdU)-labeling analysis. The initial cell-proliferation patterns of the TE teeth were similar to that at the cap and early bell stages in natural teeth. This was particularly true in the cervical loop, which showed a similar distribution pattern of BrdU-positive cells in TE- and natural teeth. These results suggested that even when embryonic tooth germs are dissociated, the single cells can reconstitute tooth, and that enamel organ morphogenesis proceeds as in natural teeth.

Animals↗

PubMed1998

The Shh signalling pathway in tooth development: defects in Gli2 and Gli3 mutants.

The expression of genes involved in the Sonic Hedgehog signalling pathway, including Shh, Ptc, Smo, Gli1, Gli2 and Gli3, were found to be expressed in temporal and spatial patterns during early murine tooth development, suggestive of a role in early tooth germ initiation and subsequent epithelial-mesenchymal interactions. Of these Ptc, Smo, Gli1, Gli2 and Gli3 were expressed in epithelium and mesenchyme whereas Shh was only detected in epithelium. This suggests that Shh is involved in both lateral (epithelial-mesenchymal) and planar (epithelial-epithelial) signalling in early tooth development. Ectopic application of Shh protein to mandibular mesenchyme induced the expression of Ptc and Gli1. Addition of exogenous Shh protein directly into early tooth germs and adjacent to tooth germs, resulted in abnormal epithelial invagination, indicative of a role for Shh in epithelial cell proliferation. In order to assess the possible role of this pathway, tooth development in Gli2 and Gli3 mutant embryos was investigated. Gli2 mutants were found to have abnormal development of maxillary incisors, probably resulting from a mild holoprosencephaly, whereas Gli3 mutants had no major tooth abnormalities. Gli2/Gli3 double homozygous mutants did not develop any normal teeth and did not survive beyond embryonic day 14.5; however, Gli2(-/-); Gli3(+/-) did survive until birth and had small molars and mandibular incisors whereas maxillary incisor development was arrested as a rudimentary epithelial thickening. These results show an essential role for Shh signalling in tooth development that involves functional redundancy of downstream Gli genes.

Animals↗

PubMed1999

Alveolar bone loss and tooth loss in male cigar and pipe smokers.

BACKGROUND: While cigarette smoking is recognized as being detrimental to oral health, the effects of cigar and pipe smoking on tooth-loss risk, alveolar bone loss and periodontal disease are not known. The authors conducted this study to determine whether cigar and pipe smokers were at greater risk of experiencing tooth loss and alveolar bone loss than were nonsmokers. METHODS: The authors studied 690 dentate men who participate in the Veterans Affairs Dental Longitudinal Study. Subjects are not VA patients, and they receive medical and dental care in the private sector. A board-certified periodontist conducted clinical examinations triennially for 23 years. These examinations included the number of teeth remaining, number of decayed and filled surfaces per tooth, and indicator scores for plaque, calculus, pocket probing depth, gingival bleeding and tooth mobility. Alveolar bone loss was assessed at each examination on intraoral periapical radiographs using the Schei ruler method, which measures loss of bone height in 20 percent increments. Multivariate analyses of tooth-loss rates and alveolar bone loss controlled for demographic and oral hygiene measures. RESULTS: The relative risk, or RR, of tooth loss compared with that of nonsmokers was significantly elevated in cigar smokers (RR = 1.3, 95 percent confidence interval, or CI, = 1.2, 1.5), pipe smokers (RR = 1.6, 95 percent CI = 1.4, 1.9) and cigarette smokers (RR = 1.6, 95 percent CI = 1.5, 1.7). The percentages of mesial and distal sites with moderate-to-severe progression of alveolar bone loss (a change of 40 percent or more from baseline) were 8 +/- 1 percent (mean +/- standard error) in nonsmokers, 16 +/- 3 percent in cigar smokers (P < .05), 13 +/- 4 percent in pipe smokers (P = .17), and 16 +/- 3 percent in cigarette smokers (P < .001). Pipe and cigar smokers did not differ significantly from nonsmokers with respect to the percentage of sites at baseline with moderate-to-severe scores for calculus, pocket probing depth, gingival bleeding or tooth mobility. Pipe smokers had fewer sites with moderate-to-severe plaque accumulation than did nonsmokers (7 +/- 11 vs. 13 +/- 17, P < .05). CONCLUSIONS: The authors found that men who smoke cigars or pipes were at increased risk of experiencing tooth loss. Cigar smokers also were at increased risk of experiencing alveolar bone loss. These elevations in risk are similar in magnitude to those observed in cigarette smokers. CLINICAL IMPLICATIONS: The increases in risk related to cigar and pipe smoking provide a strong rationale for targeting smoking prevention and smoking cessation programs to smokers of all tobacco products.

Adult↗

PubMed1993

[Osteopontin mRNA expression in remodeling alveolar bone incident to tooth movement--visualized by in situ hybridization].

The purpose of this study was to investigate the osteopontin mRNA expression in the alveolar bone incident to the physiologic and experimental tooth movement. The upper jaws of female rats (7 weeks old) which were submitted to experimental molar tooth movement and control specimens were decalcified and sliced into paraffin sections. Osteopontin mRNA expression and tartrate-resistant acid phosphatase (TRACPase) activity were examined in the alveolar bone by use of in situ hybridization techniques and enzyme histochemistry, respectively. In the control specimens high levels of osteopontin mRNA expression was observed in the osteocytes and lining cells close to the osteoclasts which were detected by TRACPase staining in the distal areas of the tooth sockets. In the mesial tooth socket areas however, low levels of osteopontin mRNA expression was observed. In the experimental specimens high levels of osteopontin mRNA expression of both the osteoblasts and osteocytes was observed in the mesial areas of tooth sockets in response to the experimental tooth movement. These results indicated that osteopontin gene expression is related to the alveolar bone remodeling as far as the bone resorption incident to the physiologic tooth movement and that this expression level significantly increased in response to a certain mechanical stress incident to the experimental tooth movement.

Alveolar Process↗

PubMed1999

A six-week clinical efficacy study of four commercially available dentifrices for the removal of extrinsic tooth stain.

The objective of this double-blind clinical study was to compare the efficacy for extrinsic tooth stain removal of four commercially available dentifrices: Colgate Tartar Control with Baking Soda & Peroxide Fluoride Toothpaste; Aquafresh Advanced Whitening Toothpaste with Fluoride; Rembrandt Tartar Control Low Abrasion Fluoride Whitening Toothpaste; and Crest Regular Fluoride Toothpaste. Following a baseline examination for extrinsic tooth stain on the anterior six mandibular and maxillary teeth, qualifying adult male and female subjects from the Philadelphia, Pennsylvania area were randomized into four treatment groups which were balanced for age, gender, tobacco habits, and level of extrinsic tooth stain. Subjects were instructed to brush their teeth twice daily (morning and evening) for one minute with their assigned dentifrice using a soft-bristled toothbrush. Examinations for extrinsic tooth stain were repeated after six weeks' use of the study dentifrices. One hundred eighty (180) subjects complied with the protocol, and completed the entire study. At the six-week examination, subjects assigned to the Colgate Tartar Control with Baking Soda & Peroxide Fluoride Toothpaste treatment group exhibited statistically lower levels of extrinsic tooth stain area and extrinsic tooth stain intensity than did those subjects assigned to the Crest Regular Fluoride treatment group. Subjects assigned to the Aquafresh Advanced Whitening treatment group exhibited significantly lower levels of extrinsic tooth stain area than did those assigned the Crest Regular Fluoride group. No other significant differences among the four study dentifrices were noted. Thus, the results of this double-blind clinical study support the conclusion that Colgate Tartar Control with Baking Soda & Peroxide Fluoride Toothpaste provides significantly greater control of extrinsic tooth stain than does Crest Regular Fluoride, a sodium fluoride/silica dentifrice.

Adult↗

PubMed1990

[Changes of vibration frequency due to root resorption of deciduous tooth].

The purpose of this study was to investigate the changes of vibration frequency of a deciduous tooth due to physiological root resorption. The author developed an analysis system for tooth vibration by applying an impact-hammer to the tooth. Peak frequency (Hz) of the tooth stimulated by the impact-hammer was observed by the analysis system. The following results were obtained: 1) Peak frequency of the tooth vibration shifted to a lower range according to the root resorption both in vitro (simulation model) and in vivo (15 children) and a high positive correlation was found between the peak frequency and the crown-root length ratio (r = 0.840). 2) A cause of the frequency shift to the lower range was not related to the tooth weight but to the change of tooth gravity due to the root resorption. 3) It was considered that the vibration analysis system could be useful on measuring tooth mobility in vivo and in clinic as well.

Child↗

PubMed1997

Risk factors associated with tooth wear in teenagers: a case control study.

OBJECTIVE: To measure the association of various aetiological risk factors with tooth wear in 15-year-old school children. BASIC RESEARCH DESIGN: A case control study conducted one year after a prevalence study (Milosevic et al., 1994). The 80 children, identified from the prevalence study with palatally and/or occlusally exposed dentine, acted as cases. The control group were systematically selected from every tenth name on year registers. The only matching criteria were age, gender and school. All children answered a questionnaire detailing the risk factors and the tooth wear was further scored by one examiner (AM). SETTING: Ten randomly selected schools in Liverpool. PARTICIPANTS: 102 children participated out of a possible 160, an overall response rate of 64 per cent. Of the 54 controls, six had developed tooth wear into dentine during the 12-month interval following the prevalence study and were therefore excluded from the analysis. RESULTS: The odds ratio on 37 matched pairs was 1.7 (95% CI 0.72, 3.87) for grinding and clenching teeth and 2.6 (95% CI 0.91, 7.45) for carbonated drink consumption. Eating pickled food other than pickled onions was significantly more frequent in cases than in controls. Other potential aetiological factors which were not significantly associated with tooth wear in this group of children included stomach upsets, frequency of tooth brushing, weight/body shape and drinking fruit juice or using ketchup/sauces. Conditional logistic regression analysis of the paired data showed that carbonated beverage consumption was on the borderline of significance (P = 0.055) as a predictor for tooth wear in teenagers either on its own or allowing for the effect of tooth grinding. CONCLUSIONS: The frequent consumption of carbonated beverages is probably related to tooth wear. Future case control studies should seek to incorporate around 100 to 160 cases.

Adolescent↗

PubMed1998

In vitro tooth whitening by a sodium bicarbonate/peroxide dentifrice.

The main purpose of this laboratory study was to determine the tooth whitening effect of a baking soda dentifrice containing stabilized 1% hydrogen peroxide following repeated applications to intrinsically stained teeth. Additional objectives were to investigate (1) the influence of tooth surface curvature and moisture on color measurements, (2) preliminary treatment parameters using 1% hydrogen peroxide solution, and (3) the relationship between Vita shade guide standards and instrumental color readings. Human tooth specimens with intrinsic stain were specially prepared and measured for color (L*a*b*) by means of diffuse reflectance spectrophotometry. Specimens were measured under wet and dry conditions with natural and flattened enamel surfaces. A preliminary test was conducted with 1% H2O2 solution to establish tooth whitening versus treatment time. Then, new tooth specimens were treated repeatedly with slurries of silica, baking soda, or baking soda/peroxide dentifrices at 30-minute intervals, and color measurements were taken under both wet and dry conditions after 4, 8, 16 and 24 hours. L*a*b* color measurements of the Vita shade guide teeth were also made in order to relate laboratory color changes to clinical effects. The parameter testing results showed that flattening the enamel surface had no effect on tooth color, but the teeth rapidly became lighter and less yellow upon air-drying. The 1% H2O2 solution caused both a significant decrease in yellow (b*) and an increase in lightness (L*). Since the reduction for b* occurred more rapidly and to a greater extent than the L* factor, the b* component may be the more important indicator of tooth whitening by bleaching. Compared to the silica and baking soda dentifrices, the baking soda/peroxide dentifrice significantly decreased the yellow color (b*) of the teeth after 8 or more hours of topical treatment. The instrumental color readings of the Vita Shade guide teeth showed that the color differences between the standards were not linear or consistent, and their accuracy for assessing clinical changes in tooth whiteness is questionable.

Color↗

PubMed1993

Increasing human tooth length between birth and 5.4 years.

Most previous studies of tooth development have used fractional stages of tooth formation to construct growth standards suitable for aging juvenile skeletal material. A simple alternative for determining dental age is to measure tooth length throughout development. In this study, data on tooth length development are presented from 63 individuals of known age at death, between birth and 5.4 years, from an archeological population recovered from the crypt of Christ Church, Spitalfields, London. Isolated developing teeth (304 deciduous, 269 permanent) were measured in millimeters and plotted against individual age. Regression equations to estimate age from a given tooth length, are presented for each deciduous maxillary and mandibular tooth type and for permanent maxillary and mandibular incisors, canines, and first permanent molars. Data on the earliest age of root completion of deciduous teeth and initial mineralization and crown completion of some permanent teeth in this sample are given, as well as the average crown height and total tooth length from a small number of unworn teeth. This method provides an easy, quantitative and objective measure of dental formation appropriate for use by archeologists and anthropologists.

Age Determination by Teeth↗

PubMed2002

Experimental tooth movement through mature and immature bone regenerates after distraction osteogenesis in dogs.

The purpose of this study was to verify the influence of tooth movement on tooth roots and periodontal tissues when teeth were moved into mature, well-organized, and mineralized regenerate bone created after distraction osteogenesis compared with immature, fibrous, and less-mineralized bone. Six 15-month-old male beagles underwent 10 mm of bilateral mandibular distraction osteogenesis. After 2-week (group 1) and 12-week (group 2) consolidation periods, third premolars were moved distally into the regenerate bone with 100 g of orthodontic force for 12 weeks. Simultaneously, second premolars were also moved distally as controls. After completion of tooth movement, the experimental animals were killed, and their tissues were harvested for histological evaluation. When premolars in groups 1 and 2 were compared, group 1 showed higher rates of tooth movement until the eighth week of experimental tooth movement (P <.05). The amount of tooth movement was significantly greater in group 1 than in group 2 or in the control teeth (P <.05). In group 1, we observed considerable root resorption extending into the dentin, and the thickness of the dentin became approximately half that of the controls at the compression side adjacent to the distraction gap. This root resorption extended from the cementoenamel junction to the root apex. In group 2, root resorption on the compression side reached the dentin, but the root resorption was less than in group 1. These results indicated that heavy force and early orthodontic tooth movement are not recommended when teeth are moved through regenerated bone created by distraction osteogenesis, to avoid tipping and severe root resorption.

Alveolar Process↗

PubMed2001

A reliability study of clinical tooth wear measurements.

STATEMENT OF PROBLEM: Most studies examining tooth wear severity have been performed on dental casts. This indirect approach has limited applicability to dental practice because during the assessment of the casts, the identification of dentin exposure is difficult or even impossible. PURPOSE OF STUDY: The purpose of this study was to assess occlusal and incisal tooth wear clinically to determine the reliability of the assessment procedure and to establish the influence of selected relevant clinical variables (dental quadrant, tooth type, and severity of wear) on the reliability. MATERIAL AND METHODS: Forty-five volunteers (17 men, 28 women; mean age 33.7 +/- 10.7 years), 32 with temporomandibular disorders and 13 free from signs and symptoms of such disorders, were evaluated on 4 occasions. Two trained observers graded tooth wear at 2 different points in time with a 5-point ordinal scale developed for use in this study. The inter-rater and intra-rater reliability of the scale was expressed as Cohen's kappa. The influence of 2 clinical variables, dental quadrant and tooth type, on the values of kappa was tested with 1-way analysis of variance and post hoc Bonferroni tests. Probability levels of P< .05 were considered statistically significant. The influence of the final clinical variable, severity of wear, was assessed qualitatively. RESULTS: The overall values of the inter-rater and intra-rater reliability were substantial (kappa = 0.632 to 0.678). The clinical variable dental quadrant did not influence the kappa values, whereas the inter-rater reliability during the first session was better for incisors and canines than for premolars (1-way analysis of variance: F(3,23)=4.577, P=.012; post hoc Bonferroni tests: P=.030 and.036). Qualitative assessment of severity of wear indicated that the more advanced the tooth wear, the more reliably it could be graded. CONCLUSION: By means of the developed 5-point ordinal scale and within the limitations of this study, it was concluded that tooth wear can be assessed reliably in the clinical dental setting.

Adult↗

PubMed1997

Expression of GDNF and its receptors in developing tooth is developmentally regulated and suggests multiple roles in innervation and organogenesis.

Glial cell line-derived neurotrophic factor (GDNF) is a recently identified survival factor for several populations of neurons in the central and peripheral nervous system that also regulates kidney development. To study the roles of GDNF in the regulation of tooth innervation and formation, we analyzed by in situ hybridization the expression patterns of GDNF and its receptors Ret, GDNF family receptor alpha-1 (GFRalpha-1), and GFRalpha-2 from the initiation of first molar formation to the completion of crown morphogenesis. At the time of trigeminal axon ingrowth, GDNF mRNAs were expressed in the mesenchyme around the tooth germ (i.e., target field of the dental innervation), suggesting that it is involved in the regulation of the embryonic tooth innervation. This hypothesis was supported by the ability of GDNF to induce neurite outgrowth from embryonic day 12 (E12) to E15 trigeminal ganglia. This timing correlated with the appearance of Ret in the subset of cells in the trigeminal ganglion at E12, whereas GFRalpha-1 and GFRalpha-2 receptors were constantly expressed in trigeminal ganglion during E11-E15. After birth, GDNF expression showed apparent correlation with the ingrowth and presence of trigeminal nerve fibers in the tooth, suggesting that GDNF is involved in the regulation of innervation of the dental papilla and dentin postnatally. Ret, GFRalpha-1, and GFRalpha-2 mRNAs were expressed in the dental epithelial and mesenchymal cells at stages when epithelial-mesenchymal signalling regulates critical steps of tooth morphogenesis. Ret and GFRalpha-2 were colocalized in the dental mesenchyme during bud and cap stages. Expression of GFRalpha-1 associated with the formation of the epithelial enamel knot, which is a putative embryonic signalling center regulating tooth shape. During postnatal development, GDNF and its receptors were expressed in dental papilla mesenchyme. In addition, GDNF and GFRalpha-1 transcripts were seen in the preodontoblasts and odontoblasts, suggesting that they may be involved in differentiation and maintenance of functional properties of the odontoblasts. Taken together, these results suggest that GDNF acts as a target-derived neurotrophic factor during tooth innervation. In addition, GDNF and its receptors may have nonneuronal organogenetic functions during tooth morphogenesis.

Animals↗

PubMed1998

Neurturin mRNA expression suggests roles in trigeminal innervation of the first branchial arch and in tooth formation.

Neurturin (NTN) is a recently characterized member of the glial cell line-derived neurotrophic factor (GDNF)-family which, like GDNF, can promote the survival of certain populations of neuronal cells in peripheral and central nervous systems. To elucidate the roles of NTN and a novel glycosyl-phosphatidylinositol (GPI)-linked receptor protein GFRalpha-3, a member of GDNF-family receptor alpha, in the regulation of peripheral trigeminal innervation and tooth formation, their expression patterns during mouse embryonic (E) and early postnatal (P) development (E10-P5) of the first branchial arch were analyzed by in situ hybridization. NTN mRNAs were observed in oral and cutaneous epithelia of the mandibular process at all studied stages and expression became gradually restricted to the suprabasal epithelial cells. In addition, transcripts were also detected in the epithelium of whisker follicles. In the developing first molar tooth germ, NTN showed a developmentally regulated, spatiotemporally changing expression pattern, which partially correlated with the development of innervation. During the initiation of tooth formation NTN mRNAs were expressed in dental epithelium and during later embryonic development transcripts appeared in the dental papilla mesenchyme. In addition, some transcripts were seen in the dental follicle. During postnatal development, NTN expression was restricted to the dental follicle of the incisor tooth germs. GFRalpha-3 mRNAs were not detected in teeth, but an intense expression was seen in non-neuronal cells surrounding trigeminal nerve fibers and in the trigeminal ganglia during E11-E15. Ganglion explant cultures showed that trigeminal neurons start to respond to exogenous NTN at E12, which correlates to the earlier reported appearance of the Ret-tyrosine kinase receptor in the trigeminal ganglion. Local application of NTN with beads on isolated dental mesenchyme did not stimulate cell proliferation or prevent apoptotic cell death. In addition, exogenous NTN had no effects on tooth morphogenesis in in vitro cultures. Taken together, because trigeminal neurons respond to NTN after first axons have reached their primary epithelial target fields, NTN is apparently not involved in the guidance of pioneer trigeminal nerves to their peripheral targets. However, our results show that NTN is a potent neuritogenic factor and, therefore, may act as a target-field-derived neurotrophic factor for trigeminal nerves during innervation of the cutaneous and oral epithelia as well as dental follicle surrounding the developing tooth. In addition, although NTN appears not to be directly involved in the regulation of tooth morphogenesis, it may have non-neuronal, organogenetic functions during tooth formation.

Animals↗

PubMed2003

Basic study on vibrations during tooth preparations caused by high-speed drilling and Er:YAG laser irradiation.

BACKGROUND AND OBJECTIVES: An Er:YAG laser effectively removes dental hard substance, and causes less pain during tooth preparations than high-speed drilling. This laser was introduced to eliminate the noise, vibration, pressure, and heat associated with the high-speed drilling. However, the difference in tooth vibration caused by the Er:YAG laser and the high-speed drill is unclear. Therefore, the aim of this study was to evaluate tooth vibration obtained with the Er:YAG laser and high-speed drill. STUDY DESIGN/MATERIALS AND METHODS: Each of the five extracted permanent upper first premolars were built up in a plaster box. In this study, a silicone impression material was selected to simulate periodontal tissue. The vibration speed was measured by using a laser Doppler vibrometer. RESULTS: The Er:YAG laser irradiation energy was 50, 100, 145, 199, 300, and 350 mJ. As irradiation energy increased, vibration of the tooth also rose; a high-correlation coefficient was observed between them. We found that only a small amount of the tooth vibration occurred with the Er:YAG laser preparations. The mean vibration speed and standard deviation with the laser were 166 +/- 28 microm/second when the output energy was 145 mJ, whereas those with the high-speed drill were 65 +/- 48 mm/second. The frequency characteristic approached 230 Hz and 5 kHz, respectively. CONCLUSIONS: These results show that the high-speed drilling causes greater tooth vibration and has a frequency spectrum near the high sensitivity of hearing compared to the Er:YAG laser. This suggests a potential factor in provoking pain and displeasure during tooth preparation. Future study to examine the relationship of pain and amount of tooth vibration will be planned.

Dental Instruments↗

PubMed2003

The role of epithelial remodelling in tooth eruption in larval zebrafish.

Based on light and transmission electron-microscopic observations on erupting first-generation teeth in the zebrafish, Danio rerio, we propose a biphasic mechanism for tooth eruption: (1). formation of an epithelial crypt prior to eruption of the tooth, possibly as a result of constraints in the epithelium resulting from the growth of adjacent tooth germs, and (2). detachment of cellular interdigitations both within the pharyngeal epithelium, at the pharyngeal epithelium/enamel organ boundary, and between the outer and inner dental epithelium, resulting in the exposure of the tooth tip in the crypt, immediately after tooth ankylosis. Later, further detachment of interdigitations between the inner and the outer enamel epithelium unfolds the epithelium even more and leads to a more pronounced exposure of the tooth tip. The presence of small patches of non-collagenous matrix on the outer surface of the tooth close to where it merges with the attachment bone is interpreted as a device to prevent complete detachment of the enamel organ. The biphasic nature of the mechanism for tooth eruption is supported by observations on in vitro cultured heads. First-generation teeth develop normally and crypts are formed, as under in vivo conditions, but the teeth fail to erupt. Taken together, our observations suggest that epithelial remodelling plays a crucial role in eruption of the teeth in this model organism.

Animals↗

PubMed1985

Effects of maternal caffeine intake on the growth of rat tooth germs in protein-energy malnourished neonates.

Fourteen rat dams with 8 pups each were fed either a 6, 12 or 20 per cent protein diet upon birth. Another group of 12 dams with the same number of pups was pair-fed either a 6, 12 or 20 per cent protein diet supplemented with caffeine (2 mg/100 g body weight). At day 15, randomly-selected pups were injected with [14C]-proline to determine collagen synthesis of the incisor and molar tooth germs. Another group of pups was used to determine calcium content of these tooth germs. Body weight, incisor weight and total calcium contents of tooth germs of pups from dams fed with 6 per cent protein diet were greater in the caffeine-supplemented group, whereas in the 20 per cent protein diet with caffeine group, these parameters were lower. The molar weights of the 12 per cent protein diet with caffeine animals were greater than the 12 per cent group without caffeine. The total hydroxyproline content of the incisor tooth germs from animals in the 12 per cent protein diet with caffeine was greater than is the non-caffeine group. However, total hydroxyproline of the molar tooth germs in the 20 per cent protein groups with caffeine was less than in the non-caffeine group. The rate of collagen synthesis of the incisor and molar tooth germs showed no difference in the presence or absence of caffeine in the 6, 12 and 20 per cent protein groups. Incisor and molar tooth germs are thus affected differently by the interaction of protein and caffeine, possibly due to differences in the pattern of tooth development.

Animals↗

PubMed1993

Is phantom tooth pain a deafferentation (neuropathic) syndrome? Part I: Evidence derived from pathophysiology and treatment.

Phantom tooth pain is a syndrome of persistent pain or paresthesia in teeth and other oral tissues that may follow dental or surgical procedures such as pulp extirpation, apicoectomy, tooth extractions, or exenteration of the contents of the maxillary antrum. It can also occur when nerves are injured after trauma to the face or even after routine inferior alveolar nerve blocks if the needle pierces the nerve sheath. In the case of tooth extraction, the pain is found in the edentate area. After periodontal surgery, pain or paresthesia is located in the gingiva. The incidence of phantom tooth pain after extirpation may be as high as 3% of cases. Clinically, phantom tooth pain is similar in many essential characteristics to deafferentation pain syndromes also known as phantom pain syndromes. A limitation to this taxonomy is the lack of definitive information with respect to the pathophysiology of deafferentation pain in the trigeminal nerve. This article amplifies previous clinical descriptions of phantom tooth pain. Current concepts in the pathophysiology of neuropathic pain are reviewed as they pertain to phantom tooth pain. Treatments are described that use three routes of drug administration: oral, nerve blocks by injections, and intranasal applications. Reasons are discussed for the high rates of morbidity after dental and neurosurgery in attempts to treat phantom tooth pain.

Afferent Pathways↗