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At least 811 records · Page 45Linked to original sources

PubMed2000

Tooth slice organ culture for cytotoxicity assessment of dental materials.

The purpose of this work was to develop a tooth slice organ culture method to assess the response of the cells of the dental pulp to commonly used dental materials and products. Wistar rat tooth slices were grown in culture for two and ten days in the presence of dental materials. After culture, the tooth tissues were processed and the responses of the pulpal cells were analysed histomorphometrically. Cytotoxic cell destruction was observed following the direct application of test materials to tooth slices (n = 298) after 10 days in culture (MANOVA, P = 0.0001), whilst the restoration of prepared deep dentine cavities (n = 30), with test products, did not result in a significant amount of pulpal injury (MANOVA, P = 0.287). In rank order of causing pulpal injury, the test materials from the most to the least cell destructive, was; Salicylic acid. Calcium hydroxide, Kalzinol zinc oxide eugenol, high-mercury Amalgam, Prime & Bond, Dycal, Barium sulphate, Hypocal, Scotchbond, Calasept, Life and One-step. Tooth slice organ culture, provided a cytotoxicity screening method for dental materials, bearing a closer physiological resemblance to the clinical situation than cell culture screening methods. Tooth slice culturing may have the potential to replace some types of in vivo animal experimentation, as there is a clear need to reduce this form of testing.

Animals↗

PubMed2000

Rapid orthodontic tooth movement into newly distracted bone after mandibular distraction osteogenesis in a canine model.

Orthodontic tooth movement through recently distracted fibrous bone tissue has not been investigated previously. We hypothesized that a tooth can be moved into the fibrous new bone created by the distraction process at a rapid rate. Four mature beagle dogs were used in this study. An edentulous space was created in 2 weeks by using a bone-borne intraoral distraction device on each side of the mandibular body between the third and fourth premolars. Calibrated elastic threads with 50 g of orthodontic force were applied to move the fourth premolar into the edentulous space for 5 weeks. On one side, the tooth was moved simultaneously with distraction; and on the opposite side, it was initiated immediately after the cessation of distraction. The fourth premolars were moved 1.2 mm per week. The results indicated that the best time to initiate tooth movement was immediately after the end of distraction. With this approach, most of the periodontal support was preserved after orthodontic tooth movement. In contrast, moderate to severe alveolar bone loss was noted in the fourth premolars moved simultaneously with distraction. This is one of the first experimental studies to demonstrate successful rapid orthodontic tooth movement into an edentulous space newly created by distraction osteogenesis. Clinical implications of these results may be applied to relieve severe dental crowding and to correct sagittal or transverse dental arch discrepancies.

Animals↗

PubMed2002

Charcot-Marie-Tooth neuropathy: clinical phenotypes of four novel mutations in the MPZ and Cx 32 genes.

Charcot-Marie-Tooth Hereditary Neuropathy is a heterogeneous syndrome associated with mutations in several different genes including peripheral myelin protein 22, myelin P0, connexin 32, and early growth response 2. There is considerable variability in the phenotypic expression of this syndrome and the relationship of this variability to mutation genotypes requires extensive analysis. Here we describe the phenotypes and genotypes of four new mutations underlying the Charcot-Marie-Tooth syndrome and document segregation with disease. Four families with Charcot-Marie-Tooth were ascertained, examined, and evaluated electrophysiologically. Each family had peripheral blood DNA screened for mutations in myelin protein 22, myelin P0, and connexin 32. Two families were found with new mutations in the myelin P0 gene: S140T in the extracellular domain and K236del in the cytoplasmic domain. All families showed segregation of the mutations with the Charcot-Marie-Tooth phenotype as did a new family with the rare G163R mutation in the membrane domain. A 49-year-old man with the S140T mutation demonstrated conduction block on electrophysiological testing. A family with a novel S49P mutation in the connexin 32 gene had a neuropathy with very slow nerve conduction. These new mutations in the myelin P0 and connexin 32 genes help to clarify the pathophysiology of the clinical Charcot-Marie-Tooth syndrome. The S140T mutation in myelin P0 can be associated with conduction block and Charcot-Marie-Tooth should be part of the differential diagnosis of that phenomenon. Mutations in the cytoplasmic domain of myelin P0 can cause clinical neuropathy. The S49P mutation in the connexin 32 gene can produce aspects of a demyelinating type of X-linked hereditary neuropathy.

Adult↗

PubMed2003

The phenotypic manifestations of autosomal recessive axonal Charcot-Marie-Tooth due to a mutation in Lamin A/C gene.

Charcot-Marie-Tooth disease constitutes a genetically heterogeneous group of hereditary motor and sensory peripheral neuropathies. The axonal type of Charcot-Marie-Tooth is designated type 2. Six loci for autosomal dominant and three for recessive Charcot-Marie-Tooth type 2 have been reported so far. In this study we report the phenotype of autosomal recessive axonal Charcot-Marie-Tooth type 2 due to a recently-described mutation (c.892C>T-p.R298C) in a gene encoding Lamin A/C nuclear envelope proteins and the first gene in which a mutation leads to autosomal recessive Charcot-Marie-Tooth type 2. We have explored eight patients from four Algerian families. The onset is usually in the second decade and the course is rapid, involving upper limbs and proximal muscles, leading to a severe condition in less than 4 years. Many different mutations in Lamin A/C have been identified as causing variable phenotypes, such as limb girdle muscular dystrophy type 1B, autosomal dominant and recessive Emery-Dreyfuss muscular dystrophy, dilated cardiomyopathy with atrioventricular conduction defect, and Dunnigan-type familial partial lipodystrophy should prompt us to fully investigate the skeletal and cardiac muscles in patients affected with autosomal recessive Charcot-Marie-Tooth type 2 carrying a mutation in LMNA.

Algeria↗

PubMed2002

Retrospective study of tooth loss in 92 treated periodontal patients.

BACKGROUND/AIMS: In this retrospective study, the efficacy of periodontal therapy and maintenance in preventing tooth loss was evaluated. METHODS: The study included 92 patients with 2310 teeth diagnosed with chronic adult periodontitis and observed over a mean period of 6.7 years, with each patient receiving surgical therapy in two or more quadrants. The group was divided into two subgroups: those who complied with the recommended maintenance schedule and those whose compliance was erratic. Individual tooth prognosis was assigned according to radiographic parameters. RESULTS: At the completion of active periodontal therapy, 2184 teeth were present. During the maintenance period, 44 teeth were lost due to periodontal reasons. Tooth mortality revealed a mean annual adjusted tooth loss rate of 0.07/year. Molars were the teeth most frequently lost; canines the least. The number of teeth lost in the three prognostic categories was: one (0.07%) for teeth with good prognoses, 21 (3.63%) for questionable prognoses and 22 (11.34%) for hopeless prognoses. Patients complying erratically with supportive periodontal therapy were at a 5.6 times greater risk for tooth loss following active therapy than regularly compliant patients. CONCLUSIONS: The results demonstrated a low tooth mortality rate in periodontal patients following active treatment combined with a strict maintenance program.

Adult↗

PubMed2002

A longitudinal evaluation of pulpal pain during orthodontic tooth movement.

OBJECTIVES: To examine the longitudinal changes in pulpal sensitivity to electrical stimulation and the relationship to pulpal sensitivity as measured by electrical stimulation and subjective reports of tooth pain after archwire insertion. DESIGN: Non-randomized, prospective trial, with matched controls. SETTING AND SAMPLE POPULATION: Regional Clinical Dental Research Center at the University of Washington School of Dentistry. Eighteen adult subjects of age 13-37 years. Nine experimental subjects planned for orthodontic treatment. Nine control subjects matched for gender and age who did not have orthodontic treatment. EXPERIMENTAL VARIABLE: Fixed orthodontic appliances and initial archwire placement in experimental subjects compared with 'no treatment' control subjects. OUTCOME MEASURE: Subjective assessments of orthodontic tooth pain were made using visual analogue scales. Electrically evoked detection and pain thresholds were determined using a computer-controlled tooth stimulator. Data were gathered at five time points: after bracket placement (baseline), 1 h after placement of initial archwires, 1 day after archwire placement, 1 week after archwire placement, and 1 month after archwire placement. Comparable time intervals were used for the 'no treatment' control subjects. RESULTS: Subjective ratings of treatment-evoked tooth pain in the experimental group were the greatest at the post-archwire day 1 observation and progressively decreased for the remaining observations. Control subjects reported little pain at any of these observation times. The detection and pain threshold changes from baseline showed no statistical differences over time or between groups. While not statistically significant, a trend was noted where reports of greater orthodontic tooth pain were associated with increased sensitivity to electrical stimulation (i.e. lower detection and pain thresholds). CONCLUSION: Orthodontic patients experience significant pain and discomfort 1 day after initial archwire placement (i.e. activation). Future research should investigate whether self-reports of treatment-evoked tooth pain intensity are associated with pulpal sensitivity.

Adolescent↗

PubMed1998

The emotional effects of tooth loss in edentulous people.

AIM: To explore the range of reactions to, and feelings about, tooth loss. METHOD: In this qualitative study, 50 edentulous people undergoing routine prosthetic dental care were interviewed privately using a reflexive, in-depth technique. All the interviews were tape-recorded and transcribed. The transcripts were scrutinised to identify the common themes related to tooth loss. Interpreter bias was minimised by two researchers scrutinising the transcripts independently. RESULTS: The participants had a mean age of 69.9 years (range 51 to 86) and had been edentulous for a mean of 18.4 years (range 0.25 to 57 years). The main themes identified in reaction to tooth loss were: bereavement, lowered self-confidence, altered self-image, dislike of appearance, an inability to discuss this taboo subject, a concern about prosthodontic privacy, behaving in a way that keeps the tooth loss secret, altered behaviour in socialising and forming close relationships, premature ageing, and lack of preparation. CONCLUSION: Tooth loss can be disabling and handicapping. It has a profound impact on the lives of some people, even those who are apparently coping well with dentures. The profession needs to consider how it can prepare people for the effects of tooth loss.

Adaptation, Psychological↗

PubMed2004

The prevalence of tooth erosion in 12-year-old children.

OBJECTIVES: To establish the prevalence of tooth erosion in a representative sample of 12-year-old children in Leicestershire and Rutland. To determine if gender, ethnic group, deprivation or caries experience influences the prevalence of erosion. METHODS: A random sample of 1,753 12-year-olds resident in Leicestershire and Rutland were examined in 62 schools; 906 were boys and 847 girls; 1,379 were Caucasian and 316 Asian. Tooth erosion was assessed using the index employed in the survey of Children's Dental Health in England and Wales (1993). The Townsend index was used to record deprivation. RESULTS: Tooth erosion was found in 59.7% of the children, with 2.7% exhibiting exposed dentine. Significantly more boys than girls; Caucasian than Asian children; and those with caries experience, had erosion present (chi-square for all P<0.01). Overall no significant difference was found between deprivation categories, however socio-economically advantaged Caucasian children had significantly less tooth erosion than other groups. CONCLUSIONS: There was a high prevalence of tooth erosion in 12-year-old children. Significantly more erosion occurred in boys than girls, and culture appeared to influence prevalence. Children with caries experience had a higher prevalence of erosion than those without caries, which may reflect a lower level of dietary care. Deprivation seemed to affect the prevalence of tooth erosion in Caucasian children.

Asian People↗

PubMed1999

Craniofacial morphology and tooth wear: a longitudinal study of orthodontic patients.

Previous research has suggested that a relationship exists between craniofacial morphology and tooth wear. The primary objective of this study was to determine whether an individual's craniofacial morphology during childhood is related to the degree of tooth wear that occurs in that same individual's adult dentition. Pretreatment orthodontic records taken during the mixed dentition (T1) and follow-up records taken an average of 20 years later (T2) were available for 165 orthodontic patients. Incisal/occlusal tooth wear was measured on a tooth-by-tooth basis from T1 and T2 casts using a four-category scoring system. Measures of craniofacial morphology were made from the T1 lateral cephalometric radiograph. Multiple regression analysis indicated that adult wear was associated with the T1 cephalometric measures of ANB (p = 0.017) and the interaction between ramal height and sex (p = 0.039). These results suggest that the craniofacial morphology observed during childhood has a small but significant relationship to adult tooth wear.

Adult↗

PubMed2005

Simulation study for a finite helical axis analysis of tooth movement.

The description of motion using a finite helical axis (FHA) is independent of the chosen coordinate system because the values of the helical axis parameters do not change with coordinate transformations. However, an intuitive understanding of tooth movement expressed by the FHA can be slightly difficult for orthodontists who have never used it. The purpose of this study was to clarify the basic behavior of the FHA to increase our understanding of the FHA during tooth movement. Parameters of the FHA were calculated in two different simulations of canine retraction. In simulation 1, as the tipping angle of the canine was increased from 5 degrees to 30 degrees, the direction vector of the FHA v approached the x-axis (tipping axis), thus increasing the rotation angle about the FHA theta. These results demonstrated that the direction vector of the FHA can indicate the axis of rotation that is most affected in three-dimensional transformation. In simulation 2, bodily tooth movement of the canine was increased from one to five mm, and the shortest distance from the origin to the FHA d increased in a linear manner. In this case, the percent increase in bodily tooth movement could be determined by the d value. This study showed that the use of FHA makes it possible to determine the torques applied to the tooth and the true bodily tooth movement during orthodontic treatment, and this may lead to a better understanding of how to move teeth.

Cuspid↗

PubMed2006

Bolton tooth size discrepancies in skeletal Class I individuals presenting with different dental angle classifications.

The objective of this study was to investigate the frequency and association of Bolton tooth size discrepancies with dental discrepancies. Forty-eight skeletal Class I, 60 Class II, and 44 Class III subjects with similar skeletal characteristics were included in this study. Analysis of variance was performed to compare the mean ratios of Bolton analysis as a function of the Angle classification and sex. To determine the prevalence of tooth size imbalances among the three groups of occlusions and the two sexes, chi-square tests were performed. To determine the correlation of tooth size imbalances with certain dental characteristics, Pearson's correlation coefficients were calculated. No statistically significant differences were determined for the prevalence of tooth size discrepancies and the mean values of Bolton's anterior and overall ratios among the occlusal groups and sexes. Bolton's anterior ratio discrepancies had significant correlations with midline shifts (P < .05) in Angle Class I cases, with U1-SN angle (P < .01) in Angle Class II cases, and with L1-APog distance (P < .05) in Angle Class III cases. Bolton discrepancies related to overall ratio had significant correlations with overjet (P < .05) in Class I cases, with overbite (P < .05) and U1-SN angle (P < .01) in Class II cases, and with IMPA (P < .01) in Class III cases. A high prevalence of tooth size discrepancies in an orthodontic patient population and the statistically significant correlation of some of these with some dental characteristics suggest that the measurement of interarch tooth size ratios might be clinically beneficial for treatment outcomes.

Adolescent↗

PubMed1999

Assessment of tooth preparation designs for posterior resin-bonded porcelain restorations.

Tooth preparation designs advocated for posterior resin-bonded porcelain restorations were evaluated for clinical application. This study examined the design of tooth preparations from stone dies for individual posterior resin-bonded porcelain onlays and complete porcelain crowns placed in a specialist practice, and compared features that provided retentive and porcelain fracture-resistance with those in the dental literature. Stone dies of tooth preparations for 57 onlay and 46 crown preparations were provided. Measurements were recorded for the tooth preparations with the aid of interocclusal silicone impressions. Proximal boxes, grooves and occlusal steps resulting from removal of amalgam restorations were common. These retentive features were more evident with onlays, and appeared larger on the distal than the mesial surfaces. Internal tooth preparation tapers or convergence angles were frequently greater than 20 degrees, leading to relatively-wide occlusal isthmus widths, especially for onlays. There were wide variations in occlusal surface reductions for the central fossae and supporting cusps. Tapers for tooth preparations were frequently more extensive, and occlusal surface reductions were often less than recommended. The implications of these differences for long-term clinical success should be resolved.

Adult↗

PubMed2003

Periodontal reasons for tooth extraction in an adult population in Jordan.

This survey studies the reasons for periodontal extraction of permanent teeth in an adult Jordanian population. A random sample of 30 general dental practitioners (GDPs) from a list of 300 GDPs (1:10) was contacted. Of these, the 26 dentists who participated in this study were asked to record teeth extracted and give reasons for extraction. Personal and demographic information and clinical details were obtained from 898 patients aged from 20 to 60 years. A total of 1,098 teeth were extracted during the 3-month study period. The results of this study revealed that dental caries (56.4% overall) was the main reason for tooth extraction, especially in 20-39 year olds. Periodontal disease (23.4% overall) was the next most frequent indication for extraction and became the commonest cause of tooth extraction in patients aged 40 years or more. Other reasons for tooth loss accounted for only 20.2% of the series. Advanced periodontal disease represented by pocketing were the dominant pathology when tooth loss occurred as the result of periodontal disease. As far as the type of tooth was concerned, the most frequently extracted teeth were molars followed by premolars, regardless of whether their loss was the result of the caries or the periodontal disease. This study suggests that caries and its consequences are responsible for more tooth loss in patients less than 40 years of age while extraction because of periodontal problems increases with age, and more commonly related to pocketing.

Adult↗

PubMedDate not supplied

Variation of tooth number in mammalian dentition: connecting genetics, development, and evolution.

A major question in modern biology is how gene mutations affect development and are translated into macroevolutionary changes in morphology. Variations in tooth number, a strategy used by many mammals to develop specialized dentitions, has been an important factor for species diversification. Changes in the number of teeth tend to occur in the reverse of the order teeth are formed during development, which also characterizes the general pattern of tooth loss observed during the evolution of placental mammals. To understand how changes at the molecular level affect the distinct stages of tooth development, we analyzed the ontogenesis of tooth growth arrest in sciurids and mice and in single and double knockout mutant mice. We show that the complexity of the genetic network that governs tooth development can change during ontogenetic trajectory, and these changes may be related to macroevolutionary changes. Furthermore, we show that the variation in tooth number in the affected members of human families bearing mutations in the MSX1 and PAX9 genes can help to understand how the genetic variations within a population can modulate evolutionary changes in dental patterning.

Animals↗

PubMed2001

Antagonistic effects of Smad2 versus Smad7 are sensitive to their expression level during tooth development.

Members of the transforming growth factor-beta (TGF-beta) superfamily regulate cell proliferation, differentiation, and apoptosis, controlling the development and maintenance of most tissues. TGF-beta signal is transmitted through the phosphorylation of Smad proteins by TGF-beta receptor serine/threonine kinase. During early tooth development, TGF-beta inhibits proliferation of enamel organ epithelial cells but the underlying molecular mechanisms are largely unknown. Here we tested the hypothesis that antagonistic effects between Smad2 and Smad7 regulate TGF-beta signaling during tooth development. Attenuation of Smad2 gene expression resulted in significant advancement of embryonic tooth development with increased proliferation of enamel organ epithelial cells, while attenuation of Smad7 resulted in significant inhibition of embryonic tooth development with increased apoptotic activity within enamel organ epithelium. These findings suggest that different Smads may have differential activities in regulating TGF-beta-mediated cell proliferation and death. Furthermore, functional haploinsufficiency of Smad2, but not Smad3, altered TGF-beta-mediated tooth development. The results indicate that Smads are critical factors in orchestrating TGF-beta-mediated gene regulation during embryonic tooth development. The effectiveness of TGF-beta signaling is highly sensitive to the level of Smad gene expression.

Animals↗

PubMed2003

Experimental autogenous tooth transplantation in the dog: a comparison between one- and two-stage surgical techniques.

Crucial if tooth transplantation is to succeed is preservation of the vitality of the cells of the periodontium and cementum of the tooth graft. Poor contact between the tissues of the recipient site and the root surface when teeth are transplanted to recipient sites prepared immediately prior to transplantation (one-stage technique) could, after transplantation, result in insufficient nutrition to the cells of the root surface and contribute to necrosis of the cells. To improve nutrition, tooth transplantation to recipient beds left to heal for 14 days was performed (two-stage technique). Clinical trials of tooth transplantation by the two-stage technique resulted in a low incidence of tooth graft loss and root resorption. The different results between these two methods, as well as difficulties in evaluating clinical trials, called for an experimental model to be established. In 5 beagle dogs, fully developed autogenous teeth were transplanted using both one-stage and two-stage surgical techniques. The control teeth were transplanted by the one-stage method to recipient beds prepared immediately before transplantation. The test teeth were transplanted using the two-stage method to recipient beds prepared and left to heal for 5 days prior to transplantation. Four pairs of teeth (1 test and 1 control) were transplanted in each dog. One pair of incisors and one pair of premolars were transplanted in the maxilla and in the mandible. Altogether 20 pairs of teeth were included in the study. One pair of teeth fractured during extraction and was therefore excluded from the study. Two pairs of teeth were lost in the first hours after transplantation. Evaluation of the remaining 17 pairs of teeth was made by routine histological examinations after a 6-month period of healing. The blinded examination failed to show a difference between the two surgical methods in terms of frequency of various types of root resorption. The differences between the results after long-term observation of human teeth transplanted by the one- and two-stage tooth transplantation techniques were not found by this experimental model.

Animals↗

PubMed2005

Tooth loss is associated with increased risk of gastric non-cardia adenocarcinoma in a cohort of Finnish smokers.

OBJECTIVE: Tooth loss has been associated with upper gastrointestinal cancer in several studies, but only one previous study used prospectively collected data. The importance of confounding by Helicobacter pylori has not previously been addressed. The objective was to determine the association between tooth loss and upper gastrointestinal cancer in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort and to determine the importance of potentially confounding dietary factors or H. pylori seropositivity. MATERIAL AND METHODS: A prospective cohort study with 29,124 subjects included 49 esophageal squamous cell carcinomas, 66 esophageal/gastric cardia adenocarcinomas, and 179 gastric non-cardia adenocarcinomas occurring between 1985 and 1999. Cox proportional hazards models adjusted for age and education were used to estimate hazard ratios (HRs) and 95% CIs. Odds ratios and 95% CIs were calculated with and without adjustment for H. pylori seropositivity in a nested case-control group to determine whether H. pylori confounded the association between tooth loss and gastric cancer. RESULTS: Tooth loss significantly increased the hazard ratio for gastric non-cardia cancer, the HR (95% CI) for edentulous subjects versus those with < 10 teeth lost was 1.65 (1.09, 2.49, respectively). No statistically significant associations were found between tooth loss and esophageal squamous cell carcinoma or esophageal/gastric cardia adenocarcinoma. Confounding by dietary factors, tobacco smoking, or H. pylori did not explain these results. CONCLUSIONS: Tooth loss was associated with increased risk of gastric non-cardia cancer, but not esophageal squamous cell carcinoma or esophageal/gastric cardia adenocarcinoma in this Finnish cohort.

Adenocarcinoma↗

PubMed2002

Sympathetic activity-mediated neuropathic facial pain following simple tooth extraction: a case report.

This is a report of a case of sympathetic activity-mediated neuropathic facial pain induced by a traumatic trigeminal nerve injury and by varicella zoster virus infection, following a simple tooth extraction. The patient had undergone extraction of the right lower third molar at a local dental clinic, and soon after the tooth extraction, she became aware of spontaneous pain in the right ear, right temporal region, and in the tooth socket. At our initial examination 30 days after the tooth extraction, the healing of the tooth socket was normal; however, the patient had a tingling and burning sensation (dysesthesia) and spontaneous pain of the right lower lip and the right temporal region, both of which were exacerbated by non-noxious stimuli (allodynia). The patient also showed paralysis of the marginal mandibular branch of the facial nerve, taste dysfunction, and increased varicella zoster serum titers. A diagnostic stellate ganglion block (SGB) 45 days after the tooth extraction using one percent lidocaine markedly alleviated the dysesthesia and allodynia. These symptoms are characteristic of neuropathic pain with sympathetic interaction. The patient was successfully treated with SGB and a tricyclic antidepressant.

Aged↗