Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Tooth Crown”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 505 records · Page 28Linked to original sources
PubMed2002

Repair characteristics of horizontal root fracture: a case report.

Radicular fractures in permanent teeth are uncommon injuries among dental traumas, comprising 0.5-7% of the cases. Fracture occurs most often in the middle-third of the root and rarely at the apical-third. The present paper reports a clinical case of a horizontal radicular fracture located between the middle- and apical-third of a upper left-central incisor followed-up for over 3 years. The tooth was extracted owing to periodontal reasons. Histomorphologically, it showed pulp-vitality preservation and root healing by hard-tissue deposition.

Adult↗
PubMed2003

Age-related changes in the human pulpal blood flow measured by laser Doppler flowmetry.

The purpose of this study was to examine the age-related changes in human pulpal blood flow (PBF). Recordings were taken from 22 clinically healthy upper central incisors in 22 healthy participants (age: 8-75 years). A Moor blood flow monitor (type MBF3D) was used to measure PBF; and subjects' electrocardiogram (ECG), mean blood pressure (BP) and heart rate (HR) were also recorded. The resting PBF was significantly decreased with the increased age of the participants (Pearson's correlation coefficient, P < 0.001). The examined tooth crown was briefly(1 s) cooled using a dental coolant, and significant reductions in PBF were induced (one-way repeated measures anova, P < 0.05). The magnitude of the reduction (%) was significantly decreased with the increased age of the participants (Pearson's correlation coefficient, P < 0.05). The findings indicate that the hemodynamics in the human pulp is reduced with age.

Adolescent↗
PubMed1999

Incisal edge reattachment: indications for use and clinical technique.

This article presents an overview of the evolution of the incisal edge reattachment procedure. Case reports are described of patients presenting with traumatised teeth in which the reattachment procedure was performed. A review is provided of present in vivo studies detailing long-term success rates in the clinical application of this procedure. Finally, a recommended technique for diagnosis and treatment is offered to improve success in this procedure which may benefit a significant segment of the paediatric and adolescent populations.

Acrylic Resins↗
PubMed1998

An immediate adhesive bridge using the natural tooth.

There are several methods available for the replacement of missing anterior teeth. These include a removable prosthesis, a conventional fixed bridge, an adhesive bridge or a dental implant. The choice of the most suitable technique depends on several factors, such as the condition of the adjacent teeth, the occlusion, the patient's wishes and the financial implications of the proposed treatment.

Acid Etching, Dental↗
PubMed2005

Fracture in the chin area: an unusual case of mandibular torus fracture.

Mandibular torus fracture as a result of accidental trauma has not been reported to date in the dental literature. This study describes the case of a young adult male who suffered multiple fractures affecting the teeth and mandibular torus secondary to chin area trauma due to a bicycle accident; the first manifestation of bone damage being left unilateral paraesthesia of the lip. An occlusal x-ray study of the affected area was made to evaluate possible fracture, as unlike centred periapical x-rays and orthopantomography, it is able to reveal the existence of a fracture line of the alveolar wall. In the associated presence of paraesthesia, a computed tomographic study is advisable.

Adult↗
PubMed2005

More evidence required to establish link between premature birth and altered oral development.

DATA SOURCES: PubMed provided the primary data source with references from identified papers being reviewed to find additional studies. STUDY SELECTION: Reports were selected of controlled studies that provided quantitative data on the effects of premature birth on jaws, dentition, dental physiology and tooth anomalies, which were published in the English language. DATA EXTRACTION AND SYNTHESIS: Two independent evaluators extracted data describing the year of publication, definition of prematurity, sample size, material and age, methods and measurements, outcomes and authors' conclusions. Correlation between deformity/alteration and prematurity, intubation and sucking habit were considered. Methodological soundness was assessed and the quality of each article categorised as low, medium or high. RESULTS: A total of 13 articles met the inclusion criteria. Quality was judged to be high for three studies, medium for nine studies and low for a single study. The chosen studies described altered palatal morphology (n=5), altered dental maturation (n=5) and altered tooth-crown dimensions (n=3). The limited evidence suggests there may be a correlation between prematurity and altered palate morphology in the short term, with oral intubation as a contributing factor. If corrected age was considered no delay was found in maturation. CONCLUSIONS: This systematic review revealed contradictory results and a dearth of longitudinal studies in this subject area. Further well-designed controlled and longitudinal studies are required before any conclusions can be made regarding the consequences of premature birth on oral development.

Comment↗
PubMed2001

Detection of simulated internal tooth resorption using conventional radiography and subtraction imaging.

OBJECTIVES: To compare the diagnostic accuracy of conventional radiography with digital subtraction imaging in the detection of simulated internal resorption. METHODS: Simulated resorption cavities were created by the sequential use of progressively larger round burs (ISO size range 006-016) in the labial wall of the coronal or apical thirds of the pulp chamber of the maxillary incisors of two cadavers. Five viewers examined 120 pairs of radiographs, one of each pair being baseline (no lesion) and the other with or without a lesion. The process was then repeated with subtraction images of the pairs of radiographs. Receiver Operating Characteristic (ROC) analysis was used to compare the diagnostic accuracy of the two imaging modalities. RESULTS: Using conventional radiography, the minimum lesion size detectable coronally was in the 'medium' range (ISO size 010 and 012 round burs), but only 'large' lesions (ISO size 014 and 016) could be detected in the apical region. The overall diagnostic accuracy of subtraction imaging was superior to conventional radiography but only significant (P<0.05) for coronal lesions. CONCLUSION: Subtraction radiography may be a useful tool for detecting and monitoring the progress of internal root resorption.

Cadaver↗
PubMed1999

Effect of appliance reactivation after decay of initial activation on osteoclasts, tooth movement, and root resorption.

Clinical orthodontists frequently reactivate appliances following decay. Studies of tooth movement and tissue responses following reactivations indicate that linear tooth movement and rapid recruitment of osteoclasts can be achieved if reactivation is timed to coincide with the latter part of the bone remodeling cycle initiated by the first activation. Both can be delayed if reactivations are timed for the early part of the previous cycle. The objective of this study was to examine tooth movement, root resorption, and osteoclast recruitment following appliance reactivation after the first activation had decayed. Bilateral orthodontic appliances were activated with 40 cN in 144 rats to mesially tip the maxillary molars. After 16 days, rats were randomized into two groups of 72. In group 1, appliances were reactivated in precisely the same manner as the first activation. In group 2, appliances were sham-reactivated. Rats were sacrificed at 1, 3, 5, 7, 10, and 14 days. Orthodontic movement was measured cephalometrically; changes in osteoclasts and root resorption were assessed at both compression and tension sites histomorphometrically; tartrate-resistant acid phosphatase (TRAP) was measured in alveolar bone and serum biochemically. Orthodontic tooth movement was linear in group 1, but osteoclasts required 3 to 5 days to appear. There were no group- or time-related differences in root resorption. Bone TRAP levels were elevated in both groups but dropped significantly (p<0.01) in group 2 at day 7. Appliance reactivations that followed decay of the first activation produced efficient tooth movement without increased risk of root resorption, but these changes were not accompanied by rapid osteoclast recruitment at compression sites. Timing appliance reactivations for the latter portion of the previous bone remodeling cycle could have significant clinical advantages because the delay period seen in tooth movement following a single activation or short-term reactivation can be avoided.

Activator Appliances↗
PubMed2001

Reduction of the hypocone of the maxillary first molar and Class III malocclusion.

This study was conducted to examine the incidence of evolutionary changes of the maxillary molars in orthodontic patients and to investigate the association of this event with craniofacial growth. Among 4,892 Japanese patients treated at the orthodontic clinic of Hiroshima University Dental Hospital, 59 patients presented with a defect of the distolingual cusp of the maxillary first molar. They consisted of 52 female patients and seven male patients with a mean age of 14.7 years. Eruption of the maxillary first and second molars was delayed and the third molar was congenitally missing in all of these patients. Thirty-seven patients exhibited Class III malocclusion (Class III evolution group). The Z scores of cephalometric measurements were compared between the Class III evolution group and the Class III control group. The latter group consisted of 37 Class III subjects with no evolutionary dental anomalies and no orthodontic history. The tooth developmental score (TDS) for each age at the initial record was compared with Nolla's standard tooth developmental score (STDS) for equivalent ages using paired t-tests. The Z scores for Ptm'-A and Ar-A were significantly smaller in the Class III evolutionary group than in the Class III control group (P < .05). The TDS for the maxillary first and second molars were significantly smaller than the STDS for these molars (P < .01). The TDS for the maxillary second molar was significantly larger than the STDS for the maxillary third molar (P < .01). This study revealed that an evolution change of the maxillary molar is more common (P < .05) in female patients than in male patients, is more frequent (P < .05) in subjects with Class III malocclusion, and is related to the anteroposterior undergrowth of the maxilla.

Adaptation, Biological↗
PubMed2002

New regression equations for predicting the size of unerupted canines and premolars in a contemporary population.

The determination of a tooth-size to arch-length discrepancy in the mixed dentition requires an accurate prediction of the mesiodistal widths of the unerupted permanent teeth. This is an essential factor in treatment planning. The aim of this study was to validate Tanaka and Johnston's analysis on 600 Syrian patients aged 14-22 years. Tanaka and Johnston's tables, equations, and approximations were modified in order to improve the accuracy of the prediction. The correlation coefficients found between the size of the permanent mandibular central incisors and maxillary first molars (31, 41, 16, and 26) and the maxillary and mandibular canines and premolars were high (r = .72 and .74, respectively). New, more accurate prediction tables applicable at earlier ages, and new regression equations were constructed. In addition, new easier approximations were developed to allow the prediction of the size of the unerupted maxillary canines and premolars by adding 6 mm to the half-widths of teeth 31, 41, 16, and 26. The analogous prediction of the size of the unerupted mandibular canines and premolars was obtained by adding 5.5 mm to the half-widths of same teeth, 31, 41, 16, and 26.

Adolescent↗
PubMed2004

Dentoskeletal features associated with unilateral or bilateral palatal displacement of maxillary canines.

The aim of the present study was to analyze the prevalence and distribution of palatally displaced maxillary canines (PDC) in a large orthodontic population, and to investigate the associations between PDC, craniofacial features, and other dental anomalies such as aplasia or small-sized upper lateral incisors. An initial sample of 5000 subjects was evaluated. The reference values were calculated in a control group of 1000 subjects that was extracted from the initial sample. Chi-squared tests were used for statistical comparisons. The prevalence rate of PDC was 2.4%, with a male-to-female ratio of 1:3. PDC subjects with low angle vertical relationships showed a significantly high prevalence rate (60.2%). Unilateral PDC was significantly associated with aplasia of upper lateral incisors, whereas bilateral PDC was associated with aplasia of third molars. PDC showed reciprocal significant associations with bilateral small-sized upper lateral incisors. None of the three hypotheses offered in support of the "guidance theory" in the etiology of PDC were corroborated by the findings of the present study. The occurrence of other dental anomalies concurrent with PDC, sex differences, and the bilateral expression of PDC, all confirm the genetic component in the etiology of this tooth disturbance.

Adolescent↗
PubMed2005

Association between growth stunting with dental development and skeletal maturation stage.

The aim of this study was to determine the influence of growth stunting on the maturation stage of the medium phalanx of the third finger (MP3) and the dental development of the left mandibular canine in 280 high school children (140 stunted and 140 normal controls; equally distributed by sex) between 9.5 and 16.5 years of age, from a representative Peruvian school. Periapical radiographs of the MP3 from the left hand were used to determine the skeletal maturity stage, according to an adaptation of the Hägg and Taranger method. Panoramic radiographs were used to determine the dental maturity stage of the lower left canine, according to Demirjian method. Stunting was determined by relating height and age, according to the World Health Organization recommendations. There was no statistically significant difference in the skeletal maturation stage (P = .134) and the dental development stage (P = .497) according to nutritional status, even when considering different age groups (P > .183). A high correlation (r = 0.85) was found between both maturity indicators regardless of the nutritional status (growth stunted, r = 0.855 and normal controls, r = 0.863) or sex (boys, r = 0.809 and girls, r = 0.892). When skeletal level was considered, correlations values were similar between advanced (r = 0.903) and average (r = 0.895) maturers but lower (r = 0.751) for delayed maturers. Growth stunting was not associated with dental development and skeletal maturity stages in Peruvian school children.

Adolescent↗
PubMed2006

Tanaka-Johnston mixed dentition analysis for southern Chinese in Hong Kong.

OBJECTIVE: To compare the prediction of unerupted permanent canine and premolar size of a comparable sample size of southern Chinese population with that of the study of Tanaka and Johnston. MATERIALS AND METHODS: Teeth on study casts of an unselected sample from a 12-year-old Hong Kong Oral Health Survey of 12-year-old children (n = 459; 295 males and 164 females) were measured in the mesiodistal dimension. A Chinese mixed dentition analysis based on the Tanaka and Johnston method was constructed with linear regression equations for prediction of the mesiodistal widths of unerupted canines and premolars. RESULTS: Sexual dimorphism was evident between southern Chinese males and females in incisors, canines, and premolars in the mesiodistal dimension. CONCLUSIONS: To predict the space (in mm) required for alignment of unerupted canine and premolars in southern Chinese children, halve the sum of the mesiodistal dimensions of the four mandibular incisors and add the respective constants for males (upper, 11.5; lower, 10.5) or females (upper, 11.0; lower, 10.0).

Bicuspid↗
PubMed2006

Occlusal development in children of African American descent. Types of terminal plane relationships in the primary dentition.

OBJECTIVE: To compare the types and depths of the terminal plane relationships (mesial step, distal step, and flush) in the primary dentitions of African American (AA) and European (E) children. MATERIALS AND METHODS: A convenience sample of 189 African American children (103 males and 86 females) was compared to a historical sample of 61 European children (39 males and 22 females, age range 2.1 to 5.2 years, mean age of 4.1 years). Plaster dental casts were analyzed for both samples. Terminal plane depth (TPD) was defined as the anteroposterior distance (APD) between the distal surfaces of the maxillary and mandibular second primary molars of dental casts registered in centric occlusion. Sample differences were evaluated using a 2-sample independent group t-test. RESULTS: Eighty-nine percent of African American children and 63% of European children exhibited a mesial step terminal plane. The average APD of the mesial step in African American children was 1.29 mm compared to 1.13 mm in European children, but this was not statistically significant (P = .18). The samples differed significantly (P = .001) in the average APD distal step relationship (AA, 1.08 mm vs E, 2.26 mm). The prevalence of distal step relationships was lower in African American children (5%) compared to European children (16%). African American children had a lower prevalence of flush terminal plane (6%) compared to European children (21%). CONCLUSIONS: In African American children as in European children, a mesial step, rather than a flush terminal plane, is the norm for the completed primary dentition.

Black or African American↗
PubMed1999

Numerical simulation of porosity-free titanium dental castings.

The objective of this research was to analyse, predict and control the porosity in titanium dental castings by the use of numerical simulation. A commercial software package (MAGMASOFT) was used. In the first part of the study, a model casting (two simplified tooth crowns connected by a connector bar) was simulated to analyse shrinkage porosity. Secondly, gas pores were numerically examined by means of a ball specimen with a "snake" sprue. The numerical simulation results were compared with the experimental casting results, which were made on a centrifugal casting machine. The predicted shrinkage levels coincided well with the experimentally determined levels. Based on the above numerical analyses, an optimised running and gating system design for the crown model was proposed. The numerical filling and solidification results of the ball specimen showed that this simulation model could be helpful for the explanation of the experimentally indicated gas pores. It was concluded that shrinkage porosity in titanium dental casting was predictable, and it could be minimised by improving the running and gating system design. Entrapped gas pores can be explained from the simulation results of the mould filling and solidification.

Chemical Phenomena↗
PubMed1998

Study of the number of roots and canals in Senegalese first permanent mandibular molars.

A study of 480 extracted first permanent mandibular molars of the Oulof people of Senegal, West Africa, revealed 15 teeth with three roots (3.12%), and 120 teeth with four root canals (25%). An extra root correlated with a sextum lingual tubercle in 20% of cases. Analysis of the pulp chambers revealed a variety of rectangular shapes. Comparison of these anomalies with their incidence in other ethnic groups extends the range of incidence of three-rooted first permanent mandibular molars in the Negroid race. This trait is described for only the second time in a Negroid population. The clinical consequences of root variation in root canal treatment are considered.

Black People↗