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At least 703 records · Page 39Linked to original sources

PubMed1999

Porcelain veneers bonded to tooth structure: an ultra-morphological FE-SEM examination of the adhesive interface.

OBJECTIVES: The porcelain veneer technique bonds a thin porcelain shell to a minimally prepared tooth surface (enamel and/or dentin) with a luting composite in combination with an adhesive system. When complete, two adhesive interfaces are formed--resin to etched porcelain and resin to tooth structure. The purpose of this laboratory investigation is to analyze the ultra-structure of these two adhesive interfaces in order to find an explanation for some clinical phenomena and/or shortcomings of bonded porcelain veneers. METHODS: The surfaces of four porcelain disks were treated successively by sandblasting, etching with hydrofluoric acid, ultrasonic cleaning, and silanizing. The effect of each step on the surface structure of the porcelain was evaluated by field-emission scanning electron microscopy (FE-SEM). In addition, the effect of acid etching the tooth surface of veneer preparations on seven extracted upper anterior teeth was similarly determined. Finally, pre-treated porcelain veneers were luted to veneer preparations on 12 extracted upper anterior teeth by means of a contemporary total-etch adhesive system and a photo-polymerizable luting composite. The tooth/luting composite and the luting composite/porcelain interface of the veneer complex were then evaluated ultra-morphologically by FE-SEM after the specimens had been etched with an argon-ion beam to enhance the surface relief. RESULTS: FE-SEM imaging of the tooth/luting composite/porcelain interface showed strong micro-mechanical interlocking of the luting composite in the micro-retentive pits both of the acid-etched tooth surface and in the etch pits of the acid-etched porcelain surface. From this ultra-morphological perspective, the etched porcelain surface is more retentive than the etched tooth surface. At the tooth surface, cervical aprismatic enamel and exposed dentin showed the least resin-receptive surface texture. However, in these areas, no separation of the interface was observed when a multi-step total-etch adhesive system was used. SIGNIFICANCE: The strong interlocking of the luting composite into the retentive etch pits of both the porcelain and tooth substrates contributes to strong adhesion of porcelain veneers with good retention. This study suggests that a modern multi-step total-etch adhesive system can produce adhesion even to the less retentive cervical enamel and exposed dentin. Further clinical research is necessary to evaluate the long-term retention of porcelain veneers and to correlate these in vitro observations with clinical performance.

Acid Etching, Dental↗

PubMed1999

The relationship between tooth cleaning behaviour and flexibility of working time schedule.

This study tested whether there is a relationship between levels of flexibility of working time schedule and the pattern (frequency of tooth cleaning), structure (range of items used in tooth cleaning), and performance (relative effectiveness of tooth cleaning measured by levels of dental plaque) of tooth cleaning. 471 Brazilian workers from both sexes aged 24 to 44 years were selected from factories, offices, banks, shops and hospitals. Behavioural, socio-economic and clinical data were collected through structured interviews and clinical examination. Data analysis included frequency distribution and simple and multiple logistic regression. The response rate was 92.5%. Simple logistic regression showed there was a highly statistically significant relationship between flexibility of the working time schedule and tooth cleaning frequency, the range of oral hygiene aids used and the level of dental plaque. All 3 associations remained highly statistically significant after adjusting for age, sex, socio-economic status and marital status. Socio-economic status was statistically significantly associated with tooth cleaning frequency, the use of oral hygiene aids and the level of dental plaque. It was concluded that high flexibility of working time schedule is related to pattern, structure and performance of tooth cleaning.

Adult↗

PubMed2003

Observable deviation of the facial and anterior tooth midlines.

STATEMENT OF PROBLEM: It has been recommended that the anterior tooth midline be placed coincidently with the midline of the face (facial midline). The location of the facial midline depends largely on the judgment of the clinician. The amount of deviation between these 2 midlines that is noticeable to the observer has not been fully investigated. PURPOSE: The observable deviation between the anterior tooth and facial midlines in a limited sample of dentate subjects was recorded. MATERIAL AND METHODS: Full facial-view, standardized photographs (x1/1.5) of 45 subjects, meeting very limited inclusion/exclusion criteria and undergoing routine dental treatment at Tel Aviv Dental School, were examined by 10 observers: 5 dentists and 5 nondental personnel who were given only a brief explanation of facial and tooth midlines. The examiners asked whether the facial and anterior tooth midlines deviated. The photographs then were scanned onto a computer screen, and the facial midline was determined by bisecting the distance between the medial angles of the eyes. The distance between a line perpendicular to this point and the contact point of the central incisors was measured by one calibrated examiner. The photographs were grouped according to the midline deviation: group 1, <1 mm; group 2, 1 to 2 mm; and group 3, >2 mm. Two photographs with oblique anterior tooth midlines were removed from the study because they were so easily detected. The observers' detection rates for the remaining midline deviation were compared and subjected to 1-way analysis of variance to identify significant differences at the 95% level of confidence. A post hoc Student t test was performed to identify significant differences among the groups. RESULTS: Dentists and nondental personnel demonstrated a similar ability to notice deviations of anterior tooth and facial midlines. Midline deviations of <1 mm (group 1) were detected by 6 of 10 observers in 4 of 29 photographs (14%). Midline deviations of 1 to 2 mm (group 2) were detected by 6 observers in 3 of 8 photographs (37%). Midline deviations of >2 mm (group 3) were detected by 6 observers in 5 of 6 photographs (83%). The greater the deviation, the higher the detection rate. Significant differences were found between group 3 and the other 2 groups (P<.01). CONCLUSION: Within the limitations of this study, the greater the deviation of anterior tooth and facial midlines, the higher the detection rate. Nearly half of the 10 observers involved in this investigation were unable to detect midline deviations of <2 mm.

Adult↗

PubMed2004

A systematic review of the survival and complication rates of fixed partial dentures (FPDs) after an observation period of at least 5 years. II. Combined tooth--implant-supported FPDs.

OBJECTIVES: The objective of this systematic review was to assess the 5- and 10-year survival of combined tooth-implant-supported fixed partial dentures (FPDs) and the incidence of biological and technical complications. METHODS: An electronic MEDLINE search supplemented by manual searching was conducted to identify prospective and retrospective cohort studies on FPDs with a mean follow-up time of at least 5 years. Patients had to have been examined clinically at the follow-up visit. Assessment of the identified studies and data abstraction was performed independently by two reviewers. Failure and complication rates were analyzed using random-effects Poisson regression models to obtain summary estimates of 5- and 10-year survival proportions. RESULTS: From a total of 3844 titles and 560 abstracts, 176 articles were selected for full-text analysis, and 13 studies met the inclusion criteria. Meta-analysis of these studies indicated an estimated survival of implants in combined tooth-implant-supported FPDs of 90.1% (95 percent confidence interval (95% CI): 82.4-94.5%) after 5 and 82.1% (95% CI: 55.8-93.6%) after 10 years. The survival rate of FPDs was 94.1% (95% CI: 90.2-96.5%) after 5 and 77.8% (95% CI: 66.4-85.7%) after 10 years of function. There was no significant difference in survival of tooth and implant abutments in combined tooth-implant FPDs. After an observation period of 5 years, 3.2% (95% CI: 1.5-7.2%) of the abutment teeth and 3.4% (95% CI: 2.2-5.3%) of the functionally loaded implants were lost. After 10 years, the corresponding proportions were 10.6% (95% CI: 3.5-23.1%) for the abutment teeth and 15.6% (95% CI: 6.5-29.5%) for the implants. After a 5 year observation period, intrusion was detected in 5.2% (95% CI: 2-13.3%) of the abutment teeth. Intrusion of abutment teeth were almost exclusively detected among non-rigid connections. CONCLUSION: Survival rates of both implants and reconstructions in combined tooth-implant-supported FPDs were lower than those reported for solely implant-supported FPDs (Pjetursson et al. 2004). Hence, planning of prosthetic rehabilitation may preferentially include solely implant-supported FPDs. However, anatomical aspects, patient centered issues and risk assessments of the residual dentition may still justify combined tooth-implant-supported reconstructions. It was evident from the present search that tooth-implant-supported FPDs have not been studied to any great extent and hence, there is a definitive need for more longitudinal studies examining these reconstructions.

Algorithms↗

PubMed1994

Tooth spaces in and prosthetic treatment received by the middle-aged and the elderly in Hong Kong.

The purpose of this study was to describe the state of the dentition of middle-aged and elderly Chinese in Hong Kong in terms of teeth present, tooth spaces, and prosthetic treatment received. In an oral health survey conducted in 1991 in Hong Kong, a sample of 372 35-44-yr-olds and 537 noninstitutionalized 65-74-yr-olds was interviewed and clinically examined. In all dentate subjects, each tooth was scored for the presence/absence of that tooth, a tooth space of 5.5 mm which had not been treated, or the presence of a denture or pontic replacing that tooth. Each denture was assessed according to a set of criteria. None of the 35-44-yr-olds were edentulous and the mean number of teeth present was 27.5. About 40% of the third molars and about 35% of the mandibular first molars were missing. For only 1% of the missing teeth had space closure resulted in missing teeth not being recorded as tooth spaces or treated tooth spaces. Overall, 72% of the 35-44-yr-olds had no prosthesis, 17% had a bridge or bridges, 12% had a denture or dentures, and 1% had both. Of the 65-74-yr-olds, 12% were edentulous, and the dentate subjects had a mean number of 17 teeth present. About 70% of the molars were missing. Overall, only 29% of the elderly had no prosthesis, 52% had a denture or dentures, 33% had a bridge or bridges, and 13% had both. Only 35% and 28%, respectively, of the middle-aged and elderly denture wearers had no complaint about their dentures.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1998

Contribution of foregut endoderm to tooth initiation of mandibular incisor in rat embryos.

Classical transplantation experiments with various amphibian tissues have shown that tooth development requires not only oral ectoderm and neural crest but also foregut endoderm. In addition, histological observation of oral membrane showed that the tooth germs are initiated in some ectodermal cells and neural crest cells adjacent to foregut endoderm. These studies suggest that tooth initiation requires the presence and cooperation of these three components. In mammals, however, there is no direct evidence that tooth formation is involved in the region of oral ectoderm adjacent to foregut endoderm. In order to elucidate the contribution of foregut endoderm to tooth formation, we established a new type of endodermal cell tracing system with a recombinant adenovirus called Adex-lacZ, and performed endodermal cell tracing in a long-term culture system. Cells labelled with Adex-lacZ were seen next to non-labelled thickening epithelium, presumptive incisor epithelium. These findings show the first direct evidence in mammals that tooth formation takes place in the specified part of oral ectoderm adjacent to foregut endoderm, suggesting that foregut endoderm plays a role in tooth initiation.

Adenoviridae↗

PubMed1971

Depolarization of the tooth pulp afferent terminals in the brain stem of the cat.

1. Tooth pulp afferent fibres belonging exclusively to the Adelta group were stimulated bi-polarly with electrical pulses applied to the dentine and the central effects of the stimulation were examined in the nucleus of the spinal trigeminal complex of anaesthetized cats.2. Field potentials evoked by single pulses to the upper or lower canine tooth pulp were explored over the nucleus of the spinal trigeminal tract in the region 5 mm caudally to the obex up to 8.5 mm rostrally to the obex. They were found to be restricted to a region of 5.5-8.5 mm rostrally to the obex, 4-5 mm laterally from the mid line, with a maximum amplitude at a depth of 5 +/- 0.5 mm.3. Antidromic action potentials were recorded from the tooth pulp afferents. The stimulating micro-electrode was inserted in the region of the medulla from which distinct field potentials could be recorded by orthodromic stimulation.4. Excitability of the central terminals of the tooth pulp primary afferents was increased when the test stimulus was preceded either by a conditioning volley in low threshold afferent fibres of the infraorbital nerve or in Adelta fibres of another tooth.5. Single pulses applied to the afferent fibres of the tooth pulp produced changes in the excitability of central terminals of the fast conducting afferent fibres of the infraorbital nerve.6. The greatly increased excitability of central terminals of tooth pulp primary afferent fibres was accompanied by a small decrease in their synaptic efficiency as estimated from the changes of the post-synaptic component of the field potential evoked by their stimulation.7. It is concluded that an analogous presynaptic control mechanism is present at the central terminals of the tooth pulp primary afferent fibres as is known for the fast conducting cutaneous system. But a difference in the specifity of the action from this afferent system is suggested. While activity from Aalpha fibres is very effective in evoking primary afferent depolarization at both fast conducting trigeminal fibres and slow conducting Adelta system, the Adelta fibre activity is effective only at the latter, and not at the former.

Action Potentials↗

PubMed1990

Distribution and response properties of cat SI neurons responsive to changes in tooth temperature.

1. The activity of 214 tooth pulp-driven neurons (TPNs) in the primary somatosensory cortex (SI) activated by electrical stimulation of the canine tooth pulp was studied in anesthetized cats. These neurons were tested for their responses to thermal stimulation of the tooth pulp. 2. One hundred fifty-five TPNs were not responsive to changes in tooth temperature (thermally insensitive, TINS-TPNs) and 59 TPNs were responsive (thermally sensitive, TS-TPNs: 38 TS-TPNs were heat sensitive and 21 were cold sensitive). TS-TPNs were also tested for responsiveness to mechanical and thermal stimulation of the skin, mucosa, or periodontal membrane. Each TS-TPN was classified on the basis of cutaneous, mucosal, or periodontal mechanical receptive-field properties as either low-threshold mechanoreceptive (LTM: 57%), wide dynamic range (WDR: 25%), nociceptive specific (NS: 10%) or pulp specific (PS: 8%). 3. TS-TPNs were distributed in an upper bank of the orbital sulcus of SI. The majority were located in laminae III (32%) and IV (60%) of area 3b. 4. Heat-sensitive LTM, WDR, PS TS-TPNs, and cold-sensitive LTM TS-TPNs were characterized by a rapid rise in firing rate during thermal stimulation of the tooth pulp. In contrast, heat-sensitive NS and cold-sensitive NS and PS TS-TPNs responded with a slow rise in firing frequency during thermal stimuli delivered to the tooth pulp. 5. A linear regression analysis was applied to the stimulus-response functions of neuronal discharges of TS-TPNs. Fifty-six percent of heat-sensitive LTM, WDR, and cold-sensitive LTM TS-TPNs showed statistically significant relation (P less than 0.5) between peak firing frequency and stimulus temperature and increasing firing frequency after increases in stimulus temperature, whereas heat-sensitive and cold-sensitive NS and PS TS-TPNs did not show a clear increase in firing frequency during the thermal stimulus. 6. These findings suggest that heat-sensitive LTM and WDR TS-TPNs and cold-sensitive LTM TS-TPNs that showed high regression coefficients in stimulus-response function may be involved in encoding the intensity of noxious thermal stimulation of the tooth pulp.

Animals↗

PubMed1997

Differential effects of noxious conditioning stimulation of the cheek by capsaicin on human sensory and inhibitory masseter reflex responses evoked by tooth pulp stimulation.

In this study, we investigated whether selective activation of nociceptive primary afferent fibers by capsaicin would induce modulations on tooth-pulp-evoked sensory or inhibitory masseter reflex responses in healthy human subjects. The contribution of central N-methyl-D-aspartate (NMDA) receptor mechanisms in capsaicin-induced effects on sensory or reflex responses was evaluated by dextromethorphan, an NMDA-receptor antagonist. The inhibitory masseter reflex was evoked by electrical stimulation (constant current, single pulses) of the upper incisor while the subject was biting at 10% of his maximal force. The sensation of the tooth pulp stimulation was evaluated by visual analogue scale (VAS). The magnitude, duration, and the the latency of the reflex were determined by bite force measurements. The inhibitor masseter reflex could be induced by non-painful tooth pulp stimulation, and the inhibition was enhanced as a function of increasing stimulus intensity. Capsaicin (1%) applied topically to the skin of the cheek produced a spontaneous burning pain sensation. During capsaicin treatment, the VAS ratings for the sensation induced by tooth pulp stimulation were significantly reduced, whereas no significant changes were found in the tooth-pulp-induced masseter reflex responses. Double-blind treatment with dextromethorphan at a dose of 100 mg (= the highest does without side-effects) had no effect on sensory or reflex responses. These data indicate that noxious stimulation of the facial skin by capsaicin induces differential effects on tooth-pulp-evoked sensory and inhibitory masseter reflex responses: Sensory responses are strongly attenuated, while masseter reflex responses are not significantly changed. Dextromethorphan at a clinically applicable dose does not influence tooth-pulp-evoked sensory or reflex responses or their modulation by capsaicin. Furthermore, the lack of modulation of the masseter reflex response by capsaicin differs from the capsaicin-induced enhancement of a nocifensive limb flexion reflex described earlier.

Administration, Cutaneous↗

PubMed1996

Msx1 controls inductive signaling in mammalian tooth morphogenesis.

Members of the Msx homeobox family are thought to play important roles in inductive tissue interactions during vertebrate organogenesis, but their precise developmental function has been unclear. Mice deficient for Msx1 exhibit defects in craniofacial development and a failure of tooth morphogenesis, with an arrest in molar tooth development at the E13.5 bud stage. Because of its potential for experimental manipulation, the murine molar tooth germ provides a powerful system for studying the role of Msx genes in inductive signaling during organogenesis. To further analyze the role of Msx1 in regulating epithelial-mesenchymal interactions during tooth morphogenesis, we have examined the expression of several potential Msx1 downstream genes in Msx1 mutant tooth germs and we have performed functional experiments designed to order these genes into a pathway. Our results show that expression of Bone Morphogenetic Protein 4 (BMP4), the HMG box gene Lef1 and the heparan sulfate proteoglycan syndecan-1 is specifically reduced in Msx1 mutant dental mesenchyme, while expression of the extracellular matrix protein tenascin is unaffected. BMP4 soaked beads can induce Bmp4 and Lef1 expression in explanted wild-type dental mesenchymes, but only Lef1 expression in Msx1 mutant dental mesenchyme. We thus conclude that epithelial BMP4 induces its own expression in dental mesenchyme in a manner that requires Msx1. In turn, we show that addition of BMP4 to Msx1 deficient tooth germs bypasses the requirement for Msx1 and rescues epithelial development from the bud stage to the E14.5 cap stage. Lastly, we show that FGFs induce syndecan-1 expression in dental mesenchyme in a manner that also requires Msx-1. These results integrate Msx1 into a regulatory hierarchy in early tooth morphogenesis and demonstrate that Msx1 is not only expressed in dental mesenchyme in response to epithelial signals, but also in turn regulates the reciprocal expression of inductive signals in the mesenchyme which then act back upon the dental epithelium. We propose that Msx genes function repetitively during vertebrate organogenesis to permit inductive signaling to occur back and forth between tissue layers.

Animals↗

PubMed2002

Dose estimation by ESR on tooth enamel from two workers exposed to radiation due to the JCO accident.

ESR dosimetry is useful to estimate the external dose for the general population as well as for occupational workers in a nuclear emergency. Three teeth were extracted from two exposed workers (A and B) related to the JCO criticality accident. Tooth enamel was carefully separated from other tooth parts and subjected to ESR dosimetry. Doses equivalent to the gamma-ray dose of 60Co were estimated as follows: for worker A, the buccal and lingual sides of the eighth tooth in the upper right side, 11.8 +/- 3.6 and 12.0 +/- 3.6 Gy, respectively; for worker B, the buccal and lingual sides of the fourth tooth in the upper right side and the fifth tooth in the upper left side, 11.3 +/- 3.4 and 10.8 +/- 3.3 Gy, 11.7 +/- 3.5 and 11.4 +/- 3.4 Gy, respectively. The estimated doses were found to be similar and not dependent on the tooth positions, whether the buccal or lingual sides in each tooth.

Dental Enamel↗

PubMed2000

Behavioral dental science: the relationship between tooth-brushing angle and plaque removal at the lingual surfaces of the posterior teeth in the mandible.

The aim of this study was to investigate the relationship between tooth-brushing angle and efficacy of plaque removal. The subjects in this study were 72 students (18-21 yrs.) from paramedical schools. They answered the questionnaire of the Hiroshima University-Dental Behavioral Inventory (HU-DBI) to assess dental health behavior, and then received examinations of tooth-brushing angle, efficacy of plaque removal and gingival condition. The examination sites of tooth-brushing angle and the efficacy of plaque removal were the lingual surfaces of the posterior teeth in the mandible. The tooth-brushing angle, efficacy of plaque removal, gingival condition and dental health behavior were significantly associated with each other. The subjects who directed the bristles of the toothbrush vertically toward the tooth surfaces had a high efficacy of plaque removal, good gingival condition and good dental health behavior. Thus, it is important to direct the bristles vertically toward the tooth surfaces for effective plaque removal. In addition, knowledge related to good dental health might be necessary to carry out effective tooth brushing.

Adolescent↗

PubMed1992

Endogenous epidermal growth factor regulates the timing and pattern of embryonic mouse molar tooth morphogenesis.

The tooth organ provides a model for discrete patterns of morphogenesis over short periods of developmental time. Studies were designed to test the hypothesis that endogenous epidermal growth factor (EGF) functions to regulate multiple cusp molar tooth morphogenesis during embryonic mouse development. The relative levels of endogenous EGF and EGF receptor (EGFR) transcripts were determined in both enamel organ epithelia and dental ectomesenchyme by reverse transcription-polymerase chain reaction (RT-PCR) assays. EGF and EGFR were localized by immunohistochemistry; both antigenic determinants were demonstrated on the same odontogenic cells in cultured tooth explants. To examine EGF-mediated signal transduction, cap stage mouse molar tooth organs (E16) were cultured in serumless, chemically-defined medium as either (i) controls, or supplemented with (ii) tryphostin (an EGF receptor kinase inhibitor), (iii) tyrphostin plus exogenous EGF, and (iv) exogenous EGF. Antisense oligodeoxynucleotide (ODN) strategy was used to investigate the functions of endogenous EGF employing (i) non-treated control, (ii) sense ODN control, (iii) antisense ODN, (iv) exogenous EGF, (v) sense ODN with exogenous EGF, and (vi) antisense ODN with exogenous EGF. Tyrphostin inhibited DNA synthesis and produced a significant decrease in the volume of the explants. These effects were recovered by addition of exogenous EGF. Antisense ODN inhibition resulted in abnormal cusp formations, decreased DNA synthesis, total DNA, RNA and protein content, and decreased stellate reticulum and tooth explant volumes. The decreased tooth size was not uniform, the most pronounced effect was in the stellate reticulum. This pattern of changes was not seen when antisense ODN treatment was supplemented with exogenous EGF. These results suggest that during cap stage of odontogenesis endogenous EGF acts to stimulate DNA synthesis, which increases the cell number of specific phenotypes within the enamel organ epithelia, and thereby regulates molar tooth morphogenesis.

Animals↗

PubMed1992

Biomechanical responses of tooth to orthodontic forces applied at the lingual bracket positions.

The present study was designed to investigate biomechanical responses of tooth to orthodontic forces applied at the lingual bracket positions. A three-dimensional finite element model of the upper central incisor was developed to analyze tooth displacements and stress distributions in the periodontal ligament. Lingual horizontal and apical vertical forces of 100 gf were applied at a point on the labial surface of the crown and at three different points on the lingual surface of the crown. Tooth displacements and stress distributions from the forces applied at the lingual points were compared with those from the labial force loading. The following results were obtained. 1. Lingual horizontal force produced almost similar patterns of tooth displacements and stress distributions, irrespective of labial and lingual application points of the orthodontic forces. 2. Apical vertical force applied at the lingual points produced more uniform tooth displacements and stress distributions than labial application of the force, although the force applied at the lingual point close to the cervix generated different patterns from those with the remaining lingual force loadings. The present results suggest an important role of the positional relation of force application points to the center of resistance. It is shown that lingual force application may produce more optimal tooth movement in terms of more uniform patterns of tooth displacements and subsequent stress distributions in the PDL.

Biomechanical Phenomena↗

PubMed2003

[The correlation between tooth pain and bioactivators changes in gingival crevicular fluid after applying orthodontic stress].

OBJECTIVE: To investigate the changes of tooth pain in patients with orthodontic tooth movement, to study the changes of bioactivators in GCF in patients with orthodontic tooth movement, and explore the correlation between pain and bioactivators in orthodontic patients. METHODS: 50 patients were included, each having one treatment tooth and one contralateral control tooth. The levels of PGE(2), P substances, IL-6 and GM-CSF in GCF of upper lateral incisor were investigated before activation and at 12th hour, 24th hour, 48th hour and 72th hour after the applying labial orthodontic force, by using highly sensitive radioimmunassay. To record the changes of pain in orthodontic patients at 12th hour, 24th hour,48th hour and 72th hour after applying stress. RESULTS: At experimental sides, total amount of GCF PGE(2), P substances(SP), IL-6 and GM-CSF levels was significantly elevated compared with that before activation. The concentration of PGE(2) and SP in GCF increased significantly and reached peak point at 24th hour in patients, while the levels of IL-6 and GM-CSF in GCF remained at higher baseline through the experiment. There was an rhythm change of periodontal pain during orthodontic tooth movement. CONCLUSION: There was an rhythm changes of pain after stress in patients with orthodontic tooth movement, and the rhythm pain was correlated to the changes of some activator such as P substances and PGE(2) in periodontal ligament.

Adolescent↗

PubMed2005

[Effects of surface potentials of tooth hard tissue on bone remodeling in rabbit tibiae].

OBJECTIVE: To investigate the influence of surface potentials of tooth hard tissue on bone remodeling. METHODS: After insured the surface potentials of human extracted teeth with electrochemical methods, teeth sections and artificial hydroxyapatite were implanted into 25 rabbits' tibiae. The rabbits were sacrificed at 1, 2, 4, 6 and 8 weeks after implantation, respectively. The bone regeneration was compared between opposite two sides (cathode side and anode side) of tooth sections using hematoxylin-eosin (HE) staining, tartrate-resistant acid phosphatase (TRAP) activity detecting and tetracycline tracing method. RESULTS: Resorption lacunae was seen in the tibiae facing to the enamel anode and new bone density in the implant bed near the cathode of tooth samples was much higher than that near the anode, while the number of TRAP positive cells near the cathode was smaller than that near the anode (P < 0.01). The fluorescent area of tetracycline tracing near the cathode was larger than that near the anode (P < 0.05). CONCLUSIONS: The cathode of tooth hard tissue (cementum) could improve or trigger new bone formation, while the other side, anode (enamel), could improve the bone resorption. This study suggests that tooth hard tissue's electrochemical characteristic might affect the remodeling of alveolar bone, and tooth supraeruption and the alveolar bone loss after tooth extraction might result from the redundant or lack of root electrochemical stimulation to bone.

Alveolar Bone Loss↗

PubMed1990

[A novel reactive polymer bonding composite resin to ground tooth substrates].

Methyl methacrylate (MMA)-p-styrene sulfonic acid copolymer (MS) was prepared and its adhesion to ground tooth substrates was evaluated. MS is crosslinked with Ca2+ supplied by hydroxyapatite in the smeared layer on the ground enamel and dentin, and sticks to their surface. The adhesion mechanism of MS is quite different from that of interpenetration and polymerization of monomers. The bonding strength of MMA-TBB resin to the tooth treated with an aqueous solution of MS was 11-12 MPa but that of MMA-BPO.DMPT resin was only 2.5 M Pa. Free sulfonic acids remaining in the immobilized MS disturbed the initiation of polymerization in MMA-BPO.DMPT resin. A photocurable liner, triethylene glycol dimethacrylate (TEGDMA) activated by d,l-comphorquinone (CQ), N-phenylglycine (NPG), which was polymerized in an acidic condition by irradiation, was chosen to obtain a high bond strength to the cross-linked MS on the tooth. The bond strength of TEGDMA-CQ.NPG on the tooth treated with an aqueous mixture of 10 wt% MS 7 (MMA: 70 mol%, p-styrene sulfonic acid: 30 mol%) and FeCl3 ([Fe3+]/[SO3-] = 0.28) was 10-11 MPa. The observation of the fractured surface after the tensile test and interface between precipitated MS and tooth indicated that the liner did not interpenetrate into the dentin through the immobilized MS on the tooth. These results indicated that the polymer reaction of MS with Ca2+ was important in the adhesion. In conclusion, MS is a reactive polyelectrolyte which adheres well to tooth substrates and prevents pulp irritation by hindering the penetration of the monomer.

Adhesiveness↗

PubMed1985

The pattern of histogenesis and growth of tooth plates in larval stages of extant lungfish.

Comparison of new data obtained in this study on Protopterus aethiopicus with that published on Protopterus aethiopicus and Neoceratodus forsteri has confirmed the suggestion that the pattern of histogenesis of tooth plates in the early larval stages is very similar in the two genera. These similarities are more apparent both when a common terminology is adopted, based on a topogenic classification, and when the fundamental assumption is made that a single morphogenetic system operates for all odontodes. The model to explain the structure of all vertebrate dentitions with separate teeth in single or multiple tooth rows has been found to apply to dipnoan dentitions with fused teeth in a composite tooth plate. In this model, the epithelial invagination surrounding the margins of the tooth plate represents the dental lamina and, where this is in contact with mesenchymal cells, cell clusters (protogerms) arise. From these protogerms new odontodes (teeth) may develop if factors to inhibit differentiation are not present. Sites for initiation of odontodes become restricted to the labial margins of existing ridges on the tooth plate. Experimental studies on mammalian tooth germs are discussed and a model proposed for control of odontogenesis and histogenesis in dipnoan dentitions. Patterns of growth of hypermineralised petrodentine have been analysed and shown to depend initially on the arrangement of odontodes, and subsequently upon the ability of special cells in the pulp to generate new and wider layers of petrodentine. The initial pattern of petrodentine depends upon the position of odontodes in the forming ridges of the tooth plate. Subsequent patterns of petrodentine depend upon the extent of replacement growth beneath the tritural surface. Specialised cells, petroblasts, secrete the petrodentine within a shell of dentine. These cells differentiate from cells of the dental papilla after odontoblasts have begun to form dentine. They are regarded as a unique type of cell for dipnoans.

Animals↗