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PubMed2000

Tooth root colour as a measure of chronological age.

The purpose of this study was to assess a possible colour shift in the root surfaces of adult human teeth and if so, whether this colour change is related to chronological age. Teeth extracted from persons of known age and gender were obtained from Ontario dental practitioners and grouped into five-year age ranges. Three experiments were undertaken: (1) to identify a possible difference in yellow colouration between the four surfaces of tooth roots (mesial, distal, lingual, and buccal), (2) to investigate the difference in yellow colouration of tooth roots between non-molar teeth and molar teeth and (3) to assess the correlation between the age of teeth and root colour saturation for yellow, magenta, cyan and black. The teeth in all investigations were scanned by a flat-bed digital colour scanner with a Kodak colour scale control and viewed on a colour computer monitor. In the first two experiments the yellow colour saturation of the root surfaces was measured at six points on each root using Photoshop 5.0 software. A significant difference was observed in the percentage yellow colour saturation between the mesial and the other three anatomical surfaces (p < 0.01), and between the root surfaces of non-molar and molar teeth (p < 0.01) (ANOVA with Bonferroni post-test). The authors then randomly assigned tooth surfaces to select an equivalent number of posterior and anterior teeth in the study, assessing the relationship between age and root colouration. Four points of colour measurement on 40 teeth (sample size permitting, see Table 1) for each known age and gender were assessed for colour saturation (cyan, magenta, yellow and black). The correlation of chronological age to colour saturation was linear for all colours, with correlation coefficients ranging from r = 0.81 to r = 0.94. The high correlation values strongly support the conclusion that chronological age is related to increased root colouration.

Adolescent↗
PubMed1989

Tooth root resorption induced in rats by diphenylhydantoin and parathyroidectomy.

Changes in bone, cartilage and the dentition in animals and man following the administration of anticonvulsant drugs resemble those seen in hypoparathyroidism and pseudohypoparathyroidism. Groups of 21-day-old rats were treated with diphenylhydantoin, parathyroidectomized, or made hypocalcaemic with a calcium-deficient diet. Histological examination revealed extensive resorption of cementum and dentine in the molars of the drug-treated and parathyroidectomized rats, but not in the hypocalcaemic or control groups. Localization of injected tetracycline by fluorescence showed that the resorption affected the distal side of the tooth roots and had occurred after root formation. No changes in cementum formation on the mesial side of the roots had occurred in any of the experimental groups. These results suggest that diphenylhydantoin induces a condition similar to pseudohypoparathyroidism in which the resistance of tooth roots to resorption is reduced.

Animals↗
PubMedDate not supplied

Clinical evaluation of 3 overdenture concepts with tooth roots and implants: 2-year results.

PURPOSE: In the present cohort study, overdentures with a combined root and implant support were evaluated and compared with either exclusively root- or implant-supported overdentures. Results of a 2-year follow-up period are reported, namely survival of implants, root copings, and prostheses, plus prosthetic complications, maintenance service, and patient satisfaction. MATERIALS AND METHODS: Fourteen patients were selected for the combined overdenture therapy and were compared with 2 patient groups in which either roots or implants provided overdenture support. Altogether, 14, 17, and 15 patients (in groups 1, 2, and 3, respectively) were matched with regard to age, sex, treatment time, and observation period. The mean age was around 67 years. Periodontal parameters were recorded, radiographs were taken, and all complications and failures were registered during the entire observation time. The patients answered a 9-item questionnaire by means of a visual analogue scale (VAS). RESULTS: One implant failed and 1 tooth root was removed following longitudinal root fracture. Periodontal/peri-implant parameters gave evidence of good oral hygiene for roots and implants, and slight crestal bone resorption was measured for both. Technical complications and service performed were significantly higher in the first year (P < .04) in all 3 groups and significantly higher in the tooth root group (P < .03). The results of the VAS indicated significantly lower scores for satisfaction, speaking ability, wearing comfort, and denture stability with combined or exclusive root support (P < .05 and .02, respectively). Initial costs of overdentures with combined or root support were 10% lower than for implant overdentures. CONCLUSION: The concept of combined root and implant support can be integrated into treatment planning and overdenture design for patients with a highly reduced dentition.

Aged↗
PubMed1997

The effects of CO2, Nd:YAG and Er:YAG lasers with and without surface coolant on tooth root surfaces. An in vitro study.

The objective of this study was to compare and contrast the morphologic changes in tooth root surfaces treated in vitro by scaling and root planing followed by irradiation with the Er:YAG laser using air/water surface cooling and the CO2 and Nd:YAG lasers, both with and without surface coolant. The experimental unit consisted of 42 freshly extracted teeth which were divided equally and randomly assigned to the following 7 treatment groups: untreated control, S/RP only, CO2 laser with and without air/water surface cooling, Nd:YAG laser with and without/air water surface cooling, and Er:YAG laser with air/water surface coolant. Specimens treated with CO2 laser irradiation were subjected to energy densities ranging from 100 to 400 J/cm2; those treated with the Nd:YAG from 286 to 1857 J/cm2; and the Er:YAG was used within a range of 20 to 120 J/cm2. The degree of morphologic change following CO2 and Nd:YAG irradiation appeared directly related to energy density but unrelated to the use of surface coolant. Laser induced surface changes included cavitation, globules of melted and resolidified mineral, surface crazing, and production of a superficial char layer. In contrast, the Er:YAG laser produced root surface changes that might be expected from acid etching, i.e., removal of the smear layer and exposure of the collagen matrix. In addition, sharply defined microfractures of the mineralized structure were noted and unlike the CO2 and Nd:YAG lasers, there was no evidence of melting or surface char. Given the parameters of this study, it appears that both the CO2 and Nd:YAG lasers alter the root surface in an undesirable manner. The Er:YAG laser, however, when used at low energy densities shows sufficient potential for root surface modification to warrant further investigation.

Acid Etching, Dental↗
PubMed1980

[Growth of the tooth root after radiation--an animal experimental study].

The extent to which root growth and tooth eruption can be influenced by irradiation trauma was studied in beagle dogs. A cobalt 60 teletherapy apparatus with various dosages between 600 rad and 2400 rad was used to inflict the trauma on the maxilla and mandible. The results showed that the delay in tooth eruption was dependent on the dosage, but erruption could not be hindered. Longitudinal growth of the roots of irradiation, independent of the level of the dose. The periodontal fibers were normally aligned as with healthy teeth; the apex was formed predominantly by surplus cellular cement.

Animals↗
PubMed1985

Tooth root growth impairment after mantle radiation in long-term survivors of Hodgkin's disease.

The tooth root growth impairment that resulted from 35 to 37 Gy mantle port radiation in 47 long-term survivors of childhood Hodgkin's disease was quantified and related to specific age groups and categories of teeth. Root measurements of the mandibular permanent canines, first and second premolars, and first and second molars were made from sequential panoramic radiographs taken at the time of radiation therapy and after the closure of root apexes. The severity of root growth impairment was greatest in patients who received radiation during the early stages of odontogenesis. With later stages of odontogenesis, and as the age increased at the time of treatment, less impairment occurred. The potential difficulties of using repeated panoramic radiographs to assess tooth lengths in longitudinal studies also were discussed.

Adolescent↗
PubMed1988

Distribution and synthesis of type I and type III collagens in developing mouse molar tooth root.

The distribution and synthesis of type I and type III collagens in the mouse molar tooth root have been investigated by correlating light and electron immunohistochemical data. Purified rabbit antibodies were raised against mouse type I and type III collagens and indirect immunoperoxidase procedures were used. In these conditions, predentin, pre-bone, and pre-acellular cementum were intensely immunostained for type I collagen. Both optic and ultrastructural data confirmed the presence of type I collagen at the epithelio-mesenchymal junction, but Hertwig's basement membranes remained unlabelled. The odontoblasts including the short polarized ones, osteoblasts, some cells of pulp mesenchyme and the perifollicular cells possessed type I collagen immunoreactivity in the rough endoplasmic reticulum (RER), Golgi complex and the secretory vesicles. Type III collagen immunoreactivity was strong in the perifollicular mesenchyme, light in the pulp mesenchyme and absent from the epithelio-mesenchymal junction, the predentin, pre-bone and pre-acellular cementum. Intracellular immunolabelling was detected at the ultrastructural level in the perifollicular cells by a faint homogeneous peroxidase deposit in the RER cisternae. Finally, these results, compared with previous biochemical and morphological data, represent the first dynamic aspect of collagens distribution and synthesis in the mouse molar root development. In terms of cell differentiation, our data also suggest that type III collagen synthesis does not occur during the odontoblast process of differentiation.

Animals↗
PubMed1994

An in vitro model for adhesion of bacteria to human tooth root surfaces.

A model mimicking bacterial colonization of dentine has been developed. It employs uniform particles of pulverized human tooth root tissue incubated with radioactively labelled bacteria. After incubation, the number of attaching bacteria is quantified. Attachment of Streptococcus mutans UA140, Actinomyces viscosus T14, and Lactobacillus casei 101 was found to be time dependent and complete within 1-3 h. Dissociation constants (Kd) of the interactions equalled 2.5 x 10(8) and 1.6 x 10(8) cells/ml, for Strep. mutants and A. viscosus, respectively. The Kd for L. casei could not be determined as attachment was not saturable. The putative tissue components involved in adherence were studied by determining the attachment of bacteria in the presence of competing strains. The results suggest that Strep. mutans and A. viscosus recognized and competed for the same ligand (probably collagen) in the dentine. L. casei attachment did not complete with the attachment of Strep. mutans and A. viscosus. Attachment of all strains was modified by preincubation with saliva and varied with bacterial strain and saliva donor.

Actinomyces↗
PubMed2006

Hedgehog pathway gene expression during early development of the molar tooth root in the mouse.

Sonic hedgehog is a secreted protein important for many aspects of embryonic development. In the developing tooth, Shh expression is restricted to the epithelial compartment and plays an important role during both initiation and subsequent coronal morphogenesis. We have investigated the expression of Shh and constituent members of the signalling pathway during early development of the molar tooth root in the mouse and find the presence of transcripts in Hertwig's epithelial root sheath. These epithelial cells of the root sheath and the surrounding apical mesenchyme of the dental papilla and follicle also expressed the Shh receptor Ptc1, agonist Smo and Gli downstream transcriptional effectors; however, this response occurred over short range. In contrast, the Shh antagonists Hip1 and Gas1 were both expressed at a distance from these responding cells, in more peripheral regions of the developing root. Transcripts of the Skn acyl transferase lacked specific expression in early root structures.

Animals↗
PubMed2006

Epithelial cells in PDL are critical in resuming the integral relation between tooth root and supporting bone after trauma--a transplantation experiment.

OBJECTIVE: The aim of this study was to determine the response of the residual epithelial network following traumatic breakdown of the periodontal ligament (PDL). METHODS: Mandibular incisor sections with PDL (experimental) and sections denuded of PDL (control) from 4- to 6-week-old Wistar-Furth rats were transplanted into the defects created in the frontal bone of the recipient syngeneic rats. At intervals, the defects with implanted teeth roots were collected and processed for histological and biochemical examination. Immunolocalization of epithelial cells was performed to monitor their phenotypic changes during transplantation healing period. RESULTS: (1) Histological observation of the experimental sample revealed the sequence of cellular response characterized by an initial degeneration of PDL followed by a proliferation of granulation tissue. There was also a marked odontoblastic reaction with extensive deposition of regular dentine within the pulp chambers. In the control group, initial signs of bony fusion with dentine led to an extensive ankylosis and bone replacement between roots and defects. (2) Immunostaining indicated that, in experimental groups, the pattern of regularly spaced epithelial cells lying in close approximation to the root surface was distinct 10 days post-transplantation but became diminished afterwards. The immunoreaction against epithelial cells was negative in the control. CONCLUSION: Residual PDL is essential to prevent ankylosis after trauma and epithelial cells may facilitate the re-establishment of root-PDL-bone complex by transforming into mesenchymal cells.

Animals↗