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PubMed2006

The sequential seeding of epithelial and mesenchymal cells for tissue-engineered tooth regeneration.

Progress is being made toward regenerating teeth by seeding dissociated postnatal odontogenic cells onto scaffolds and implanting them in vivo, but tooth morphology remains difficult to control. In this study, we aimed to facilitate tooth regeneration using a novel technique to sequentially seed epithelial cells and mesenchymal cells so that they formed appropriate interactions in the scaffold. Dental epithelium and mesenchyme from porcine third molar teeth were enzymatically separated and dissociated into single cells. Mesenchymal cells were seeded onto the surface of the scaffold and epithelial cells were then plated on top so that the two cell types were in direct contact. The cell-scaffold constructs were evaluated in vitro and also implanted into immunocompromised rats for in vivo analysis. Control groups included constructs where direct contact between the two cell types was prevented. In scaffolds seed using the novel technique, alkaline phosphatase activity was significantly greater than controls, the tooth morphology in vivo was developed in similar to that of natural tooth, and only one tooth structure formed in each scaffold. These results suggest that the novel cell-seeding technique could be useful for regulating the morphology of regenerated teeth.

Alkaline Phosphatase↗

PubMed2006

Sprouty genes control diastema tooth development via bidirectional antagonism of epithelial-mesenchymal FGF signaling.

Unlike humans, who have a continuous row of teeth, mice have only molars and incisors separated by a toothless region called a diastema. Although tooth buds form in the embryonic diastema, they regress and do not develop into teeth. Here, we identify members of the Sprouty (Spry) family, which encode negative feedback regulators of fibroblast growth factor (FGF) and other receptor tyrosine kinase signaling, as genes that repress diastema tooth development. We show that different Sprouty genes are deployed in different tissue compartments--Spry2 in epithelium and Spry4 in mesenchyme--to prevent diastema tooth formation. We provide genetic evidence that they function to ensure that diastema tooth buds are refractory to signaling via FGF ligands that are present in the region and thus prevent these buds from engaging in the FGF-mediated bidirectional signaling between epithelium and mesenchyme that normally sustains tooth development.

Adaptor Proteins, Signal Transducing↗

PubMed2006

Accuracy of developing tooth length as an estimate of age in human skeletal remains: the deciduous dentition.

Dental age assessments are widely used to estimate age of immature skeletal remains. Most methods have relied on fractional stages of tooth emergence and formation, particularly of the permanent dentition, for predicting the age of infants and very young children. In this study, the accuracy of regression equations of developing deciduous tooth length for age estimation (Liversidge et al.) is tested on a sample of 30 Portuguese subadult skeletons of known age at death. Overall the method shows high accuracy and the average difference between estimated and chronological age is between 0.20 and -0.14 years when using single teeth, and 0.06 years, when using all available teeth. However, there is a tendency for the deciduous molars to provide overestimates of chronological age. Results show that age estimates can be obtained within +/-0.10 years with a 95% confidence interval when several teeth are used. Overall between-tooth agreement in age estimates decreases with increasing age but there is less variability of estimates with more teeth contributing to overall mean age. One seemingly limitation of this method may be the fact that it was developed by combining the maxillary and mandibular teeth. The other is related to the accuracy with which radiographic tooth length can be used as a valid surrogate for actual tooth length. Nevertheless, the advantages of this metric method surpass the limitations of chronologies based on stages of dental development.

Age Determination by Teeth↗

PubMed2005

A comparison of post-operative complications following wisdom tooth surgery performed with sterile or clean gloves.

This randomised prospective study aimed at evaluating possible differences in the post-operative complication rate following lower wisdom tooth surgery performed with either sterile or clean surgical gloves. The microbiological profiles of the tooth sockets and glove surfaces were also evaluated and compared. A total of 275 ASA I, non-smoking and non-drinking patients consented to be randomly assigned into two groups for lower wisdom tooth surgery, performed by operators wearing either sterile or clean gloves. All the patients returned for a post-operative assessment visit one week later. An additional 40 patients were recruited and randomised into the sterile glove group (n = 20) or the clean glove group (n = 20) for the microbiology study. Specimens were taken from the glove surfaces and the post-operative socket wounds during wisdom tooth surgery. This clinical trial showed no significant difference between the sterile and clean glove groups in the incidence of acute inflammation, acute infection and dry sockets in the wounds. No single peri-operative factor had a statistically significant effect on post-operative pain intensity. Most of the bacterial isolates from the clean gloves were Gram-positive cocci or spore-forming bacilli. The total number of colony forming units and the variety of bacterial isolates from the socket wounds in the sterile and clean glove groups were similar. The study concluded that there was no advantage in using sterile surgical gloves rather than clean gloves to minimize post-operative complications in wisdom tooth surgery. There was also no apparent relationship between the bacteria contaminating the clean glove surfaces and those isolated from the socket wounds.

Adolescent↗

PubMed2006

Reasons for permanent tooth extraction in the North of Afghanistan.

OBJECTIVES: The aim of this study was to study the pattern of and reasons for permanent tooth extraction in a group of Afghan patients attending a dental clinic in the North of Afghanistan. METHODS: A simple clinical survey was done in Afghan population sample that has undergone or planned for tooth extraction. RESULTS: A total of 184 permanent teeth were extracted from 123 patients ranging in age from 9 to 62 years during the three-month study period. Males were 54.5% while females formed 45.5%. Overall, caries was the most frequent reason for tooth extraction (59.2%), followed by periodontal disease (35.3%), surgical indications (4.9%) and patient request (0.5%). Caries was the main reason for tooth loss up to 50 years of age. However, periodontal disease became the principal reason in 51 years old and over. Posterior teeth represented the highest percentage (84.2%) of extraction. CONCLUSIONS: Both caries and periodontal disease were the main reasons for tooth extraction in the North of Afghanistan, so that proper oral health system including efficient programs focusing on prevention and treatment of these diseases should be created and developed.

Adolescent↗

PubMed2004

Fixed partial denture or single-tooth implant restoration? Statistical considerations for sequencing and treatment.

The choice to replace a single missing tooth can be based on the primary decision that the restorability of the tooth is in doubt. Many teeth are decimated by incipient or recurrent caries, trauma, endodontic complications, or periodontal disease which requires extraction. It is our objective to familiarize the participant with literature comparing success rates of fixed partial dentures and single-tooth implant restorations and a repertoire of prosthodontic techniques used in replacement of single missing teeth with osseointegrated dental implants. The fixed partial denture (FPD) has been regarded as the standard of care for some time in replacement of single and multiple missing teeth. Many studies surveying long term survival have been compiled and analyzed to arrive at a generalized outcome. Most of these studies arrive at common conclusions. Studies surveying success of single-tooth implant-supported restorations are not comparably abundant nor survey for comparable time as those for FPDs. Although, many of the outcomes are statistical survival estimates such as Kaplan-Meier survival tables, implant restorations in partially dentate patients are a predictable means of tooth replacement. There are certain factors which make FPD more appropriate and conversely factors which make an implant restoration more appropriate. Indications and contraindications for each treatment scenario will also be reviewed based on the literature and clinical experience. It is hoped that the practitioner will be able to appropriately identify those cases in which either an FPD or an implant restoration is the appropriate treatment option.

Contraindications↗

PubMed2005

Correlation of papilla to crestal bone levels around single tooth implants in immediate or delayed crown protocols.

PURPOSE: The purposes of this study are to determine if there is a difference in the papilla fill between implant and teeth comparing immediate provisionalized and delayed single tooth implant restorations, and to determine the relationships between the vertical and horizontal bone levels to papilla filling the inter-dental region with single implant restorations. PATIENTS AND METHODS: Two groups of patients treated with single tooth implant restorations were prospectively followed. One group had immediate provisionalization of their implants, and the second group a delayed approach. Serial radiographs and photographs were used to collect bone level measurements for the vertical distance between contact point to bone level on the adjacent tooth, implant, and the midcrestal region. The horizontal distances were also recorded. Papilla morphology was scored 1 through 4. Univariate analysis was used to evaluate the relationships between bone levels and papilla morphology. RESULTS: There were no differences between papilla or bone levels comparing immediate provisionalization to delayed approaches. There were significant ( P < .05) relationships between the vertical distance from contact point to bone levels, with the distance from the contain point to the adjacent tooth the distance most critical to papilla maintenance. There were no significant relationships between horizontal distance and papilla maintenance. CONCLUSION: As the distance from the contact point to the implant increased, there was a significant chance of loss of papilla. There was no difference between delayed or immediate provisionalization and papilla scores. The horizontal distance from adjacent tooth bone level did not correlate to papilla score within the range of clinically relevant distances.

Adult↗

PubMed2006

Fish oil reduces tooth loss mainly through its anti-inflammatory effects?

Competing at several steps of arachidonic acid metabolism, n-3 fatty acids reduce production of highly active prostaglandins and leukotrienes and exert anti-inflammatory effects. They are also experimentally shown to be anti-osteoporotic. Periodontitis is responsible for most tooth loss in adult populations. If enough n-3 fatty acids are provided, periodontitis with alveolar bone resorption may be controlled, and tooth loss may be prevented. In fact, n-3 fatty acid administration lowered prostaglandin E(2) production, tooth movement and alveolar bone resorption in animal experiments. Aggression, which may be related with tooth loss, was also controlled with fish oil. Our cross-sectional data supported our hypothesis. We recruited 256 men (22-59 y of age) and 95 women (22-66 y), counted the numbers of their remaining teeth, and analyzed the fatty acid composition of the total phospholipid fraction of RBCs. The beta-coefficient of the numbers of remaining teeth and EPA concentrations in the fraction was 0.89 (per 1% EPA, p=0.007) after adjustment for 9 possible confounding factors. Long-term intervention studies with fish oil planned in the future should be able to test our hypothesis by just adding another very simple endpoint in those studies: tooth loss during the intervention period. This hypothesis may explain the linkage between periodontitis/tooth loss and coronary heart disease.

Adult↗

PubMed2006

Treatment of external inflammatory root resorption after autogenous tooth transplantation: case report.

This paper describes a case of autogenous tooth transplantation. An external inflammatory root resorption developed in a 30-year-old female patient and was successfully treated with the placement of calcium hydroxide-based intracanal dressings. Autotransplantation of tooth 32 into the extraction socket of tooth 30 was carried out with no intraoperative complications and uneventful postoperative course. However, the patient did not appear on the 14th postoperative day to initiate endodontic therapy of the transplanted tooth. She did not return for 3 months, at which time the clinical and periapical radiographic examinations revealed the presence of external inflammatory root resorption. Endodontic treatment was initiated immediately. Root canals were prepared and filled with a calcium hydroxide-based intracanal dressing (Calen paste), changed every 21 days during a 6-month period, and were thereafter obturated with Sealapex calcium hydroxide-based sealer and gutta-percha points. After 2 years of follow-up, the transplanted tooth was symptom free with no exacerbated sensibility to percussion, normal mobility, occlusion, and masticatory function. Probing revealed no periodontal pockets or other pathological signs. Radiographic examination showed the periradicular area with normal appearance, completely healed resorption areas, and presence of an intact lamina dura.

Adult↗

PubMed2004

Runx2 mediates FGF signaling from epithelium to mesenchyme during tooth morphogenesis.

Runx2 (Cbfa1) is a runt domain transcription factor that is essential for bone development and tooth morphogenesis. Teeth form as ectodermal appendages and their development is regulated by interactions between the epithelium and mesenchyme. We have shown previously that Runx2 is expressed in the dental mesenchyme and regulated by FGF signals from the epithelium, and that tooth development arrests at late bud stage in Runx2 knockout mice [Development 126 (1999) 2911]. In the present study, we have continued to clarify the role of Runx2 in tooth development and searched for downstream targets of Runx2 by extensive in situ hybridization analysis. The expression of Fgf3 was downregulated in the mesenchyme of Runx2 mutant teeth. FGF-soaked beads failed to induce Fgf3 expression in Runx2 mutant dental mesenchyme whereas in wild-type mesenchyme they induced Fgf3 in all explants indicating a requirement of Runx2 for transduction of FGF signals. Fgf3 was absent also in cultured Runx2-/- calvarial cells and it was induced by overexpression of Runx2. Furthermore, Runx2 was downregulated in Msx1 mutant tooth germs, indicating that it functions in the dental mesenchyme between Msx1 and Fgf3. Shh expression was absent from the epithelial enamel knot in lower molars of Runx2 mutant and reduced in upper molars. However, other enamel knot marker genes were expressed normally in mutant upper molars, while reduced or missing in lower molars. These differences between mutant upper and lower molars may be explained by the substitution of Runx2 function by Runx3, another member of the runt gene family that was upregulated in upper but not lower molars of Runx2 mutants. Shh expression in mutant enamel knots was not rescued by FGFs in vitro, indicating that in addition to Fgf3, Runx2 regulates other mesenchymal genes required for early tooth morphogenesis. Also, exogenous FGF and SHH did not rescue the morphogenesis of Runx2 mutant molars. We conclude that Runx2 mediates the functions of epithelial FGF signals regulating Fgf3 expression in the dental mesenchyme and that Fgf3 may be a direct target gene of Runx2.

Animals↗

PubMed2005

An exposure-based risk assessment approach to confirm the safety of hydrogen peroxide for use in home tooth bleaching.

Hydrogen peroxide has a long history of safe use in a wide variety of medical and consumer products, including oral care products. The use of hydrogen peroxide in tooth bleaching has been extended to home use. Because this represents a new use, questions have been raised regarding safety, particularly the potential for peroxide tooth-whitening products to increase the risk of oral cancer in high-risk individuals (e.g., smokers and drinkers). These concerns are based on limited experimental data in animals that hydrogen peroxide has extremely weak tumor promoting activity and a lack of publicly available data on exposure to peroxides from the home use of tooth-whitening products. This paper provides a weight-of-evidence cancer hazard characterization for hydrogen peroxide and presents a quantitative risk assessment that confirms a favorable human safety profile risk associated with low levels of exposure to hydrogen peroxide from the use of tooth-whitening products. This includes a lack of tumor promotion risk which is important because tooth-whitening products are often used by chronic smokers and drinkers, who may represent a susceptible subpopulation because of their exposure to other known carcinogens.

Alcohol Drinking↗

PubMed1997

Spatiotemporal expression of the homeobox gene S8 during mouse tooth development.

The murine S8 gene encodes a nuclear homeodomain containing transcription factor that is expressed at sites of epithelial-mesenchymal interactions, including those in cranofacial tissues. The spatiotemporal expression of S8 mRNA was examined in tooth primordia by in situ hybridization. S8 transcripts were found in all stages of tooth development in 13- to 16.5-day-old mouse embryos (E13-E16.5), covering the early bud stage up to the late bell stage. S8 mRNA was found exclusively in the ectomesenchyme and its derivatives that originate from the neural crest: future pulp cells, odontoblast precursors and dental follicle cells. Expression was highest at the late cap and early bud stages and declined at the mid-bell stage, in both first molar and incisor primordia. In E13 jaw explants grown in organ culture for 48 h, S8 mRNA was still present in first and second molar primordia after culture. At E15.5, S8 mRNA was also transiently present in the surrounding osteogenic tissue. It is concluded that the distribution pattern of S8 mRNA during tooth development indicates a role for the gene in defining the identity of dental papilla and follicle cells. It is speculated that the time-restricted expression of S8 in tooth primordia involves establishing the definitive form of the tooth organ.

Animals↗

PubMed1998

Sibling similarities in the tempo of human tooth mineralization.

The extent of tooth mineralization is a useful estimate of a child's physiological age it reflects the rate at which the child is developing towards maturity. As it is not known to what degree dental age is regulated by the genotype, this investigation estimated familial resemblance in the tempo of tooth mineralization. Panoramic radiographs of the children in 185 sibships were scored for stages of tooth formation, and dental age was calculated from sex-specific standards. Intraclass correlations of mineralization tempo were computed for maxillary and mandibular canines, premolars, second molars, and third molars. Correlations of mineralization tempo were significantly different than zero for all 10 teeth and ranged from 0.17 (SE = 0.06) for the mandibular second molar to 0.43 (SE = 0.05) for the mandibular second premolar. Intraclass correlations increased significantly when multiple teeth were used to more comprehensively define each child's dental age. Using an unweighted average of all 10 tooth types yielded a correlation of 0.41 (SE = 0.05). It appears, then, that a considerable proportion of the total variability in tooth-mineralization rate can be attributed to transmissible effects operating in the population under investigation.

Adolescent↗

PubMed1998

Regulation by serotonin of tooth-germ morphogenesis and gene expression in mouse mandibular explant cultures.

Serotonin (5-HT) stimulates tooth-germ development in embryonic mouse mandibular explant cultures, but it is not clear whether this is due to a direct action on epithelial-mesenchymal interactions, or whether development was stimulated indirectly by serotonergic regulation of other morphoregulatory molecules. A calcium-binding protein, S-100beta, and the extracellular-matrix molecule, tenascin, two molecules thought to be important in craniofacial development, together with cartilage proteoglycan core protein, a marker for chondrogenesis, are modulated by serotonergic ligands in mandibular micromass cultures. Here, it was demonstrated that 5-HT stimulates expression of cartilage proteoglycan core protein, and inhibits expression of S-100beta and tenascin in mandibular explants. Further, ondansetron (Zofran), a 5-HT3 receptor antagonist, and NAN-190, a 5-HT1A antagonist, reversed the serotonergic stimulation of core protein and tooth germ development. In contrast serotonergic modulation of S-100beta and tenascin expression was not reversed by any of the 5-HT receptor antagonists tested, although the 5-HT uptake inhibitor, fluoxetine, did reverse the effect of 5-HT on S-100beta expression, as well as tooth-germ development. These results support previous work suggesting that 5-HT plays an important part in craniofacial development, especially in dentinogenesis and chondrogenesis. However, the possibility that tenascin or S-100beta mediate the effects of 5-HT on tooth-germ development is not supported. Rather, these results raise the possibility that 5-HT may exert effects directly on tooth-germ morphogenesis mediated by intracellular uptake of 5-HT and/or activation of 5-HT1A and 5-HT3 receptors.

Aggrecans↗

PubMed2000

Etched porcelain veneer restoration of a primary tooth: a clinical report.

The treatment of a retained primary tooth in the adult dentition has always been a difficult clinical problem. In the anterior region of the mouth, the problem is further complicated by esthetic requirements. In this clinical report, a primary canine was recontoured both incisally and interproximally with an etched porcelain veneer to provide an esthetic result. The use of etched porcelain as an indirect veneer material, which has demonstrated clinical success, is an alternative to the requirements of conservative dentistry, namely, preservation of tooth substance and safeguarding primary tooth vitality. The procedure used in this clinical report differs from traditional procedures. The preparation was extended to the lingual surface of the tooth, which allowed for an increase of the incisal length and added a sufficient amount of porcelain. The etching procedure was performed twice by applying 30% phosphoric acid etchant gel to the prepared tooth.

Adult↗

PubMed2003

Bond strengths of porcelain laminate veneers to tooth surfaces prepared with acid and Er,Cr:YSGG laser etching.

STATEMENT OF PROBLEM: The erbium, chromium: yttrium, scandium, gallium, garnet (Er,Cr:YSGG) hydrokinetic laser system has been successful in the ablation of dental tissues. It has been reported that this system is also useful for preparing tooth surfaces for adhesion, but results to date have been controversial. PURPOSE: This in vitro study evaluated the bond strengths of porcelain laminate veneers to tooth surfaces after etching with acid and Er,Cr:YSGG laser conditioning. Material and method Forty extracted caries- and restoration-free human maxillary central incisors were used. The teeth were sectioned 2 mm below the cementoenamel junction. The crowns were embedded in autopolymerizing acrylic resin with the labial surfaces facing up. The labial surfaces were prepared with.05 mm reduction to receive porcelain veneers. The teeth were divided into 4 groups of 10 specimens. Thirty specimens received 1 of the following surface treatments before the bonding of IPS Empress 2 laminate veneers: (1) laser radiation from an Er,Cr:YSGG laser unit; (2) 37% orthophosphoric acid; and (3) 10% maleic acid. Ten specimens received no surface treatment and served as the control group. The veneers were bonded with dual-polymerizing resin, Variolink II. One microtensile specimen from each of the cervical and incisal thirds measuring 1.2 x 1.2 mm was prepared with a slow-speed diamond saw sectioning machine with a diamond-rim blade. These specimens were attached to opposing arms of the microtensile testing device with cyanoacrylate adhesive and fractured under tension at a crosshead speed of 1 mm/min, and the maximum load at fracture (Kg) was recorded. The data were analyzed with a 2-way analysis of variance and Tukey HSD tests (alpha=.05). RESULTS: No statistically significant differences were found among the bond strengths of veneers bonded to tooth surfaces etched with Er,Cr:YSGG laser (12.1 +/- 4.4 MPa), 37% orthophosphoric acid (13 +/- 6.5 MPa), and 10% maleic acid (10.6 +/- 5.6 MPa). The control group demonstrated the lowest bond strength values in all test groups. Statistically significant differences were found between the bond strengths of cervical and incisal sections (P<.001). CONCLUSION: In vitro microtensile bond strengths of porcelain laminate veneers bonded to tooth surfaces that were laser-etched showed results similar to orthophosphoric acid or maleic acid etched tooth surfaces.

Acid Etching, Dental↗

PubMed1996

An in vitro investigation of the tooth strains associated with four different restorations in Class II cavity.

The purpose of this study was to examine tooth strains in Class II preparations. A Class II cavity was prepared in 16 permanent premolars, and a strain gauge was attached to the buccal surface of each tooth. Each cavity was then restored with bonded amalgam, bonded gallium, composite, or composite with a resin liner. The tooth strains created by these four restorations were determined and evaluated with a strain indicator. The results of this study indicated that composite restorations with and without resin liner created much greater strains to tooth structure than did bonded amalgam and bonded gallium restorations. The application of resin liner before placement of the composite was effective for decreased tooth strain.

Alloys↗

PubMed2001

Treatment of tooth fracture by medium-energy CO2 laser and DP-bioactive glass paste: the interaction of enamel and DP-bioactive glass paste during irradiation by CO2 laser.

Acute trauma or trauma associated with occlusal disturbance can produce tooth crack or fracture. Although several methods are proposed to treat the defect, however, the prognosis is generally poor. If the fusion of a tooth fracture by laser is possible, it will offer an alternative to extraction or at least serve as an adjunctive treatment in the reconstruction. We have tried to use a continuous-wave CO2 laser and a newly developed DP-bioactive glass paste (DPGP) to fuse or bridge tooth crack or fracture lines. Both the DP-bioactive glass paste and tooth enamel have strong absorption bands at the wavelength of 10.6 microm. Therefore, under CO2 laser, DPGP and enamel should have an effective absorption and melt together. The interface between DPGP and enamel could be regarded as a mixture of DPGP and enamel (DPG-E). The study focused on the phase transformation, microstructure, functional group and thermal behavior of DPG-E with or without CO2 laser irradiation, by the analytical techniques of XRD, FTIR, DTA/TGA, and SEM. The results of XRD showed that the main crystal phase in the DPG-E was dicalcium phosphate dihydrate (CaHPO4.2H2O). It changed into CaHPO4, gamma-Ca2P2O7, beta-Ca2P2O7 and finally alpha-Ca2P2O7 with increasing temperature. In the FTIR analysis, the 720 cm(-1) absorption band ascribed to the P-O-P linkage in pyrophosphate rose up and the intensities of the OH- bands reduced after laser irradiation. In regard to the results of DTA/TGA after irradiation, the weight loss decreased due to the removal of part of absorption water and crystallization water by the CO2 laser. SEM micrographs revealed that the melted masses and the plate-like crystals formed a tight chemical bond between the enamel and DPGP. We expect that DPGP with the help of CO2 laser can be an alternative to the treatment of tooth crack or fracture.

Carbon Dioxide↗