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At least 1,009 records · Page 56Linked to original sources
PubMed1997

Accuracy of apex locator.

An evaluation of the accuracy of the "Root ZX" apex locator was conducted on 20 single-rooted teeth that had been extracted because of severe disease or orthodontic treatment. After the pulp chamber had been accessed and the tooth length determined using the Root ZX apparatus, the file was fixed to the tooth with light-cured composite resin. After extraction, the tooth was longitudinally ground with a diamond bur until the file was visible. The distance between the file tip and the apical foramen was measured under a microscope (x 100). The results showed that the tip of the instrument reached the apical foramen in all teeth.

Adult↗
PubMed1998

The external and internal anatomy of human mandibular canine teeth with two roots.

This study investigated the internal anatomy of 65 human mandibular canines with two well-defined roots. The teeth were decalcified and injected with gelatin coloured with india ink. Diaphanization was carried out using clear resin to allow permanent preservation. It was found that all mandibular canines with two roots had two root canals. Lateral canals were found in 68.9% of teeth and 19.7% had lateral canals at the bifurcation. The results of the external measurements (cusp tip to root apex) showed that the average buccal root length was 23.0 mm and the average lingual root length was 22.7 mm. The maximum and minimum buccal lengths were 26.7 mm and 17.9 mm respectively and the maximum and minimum lingual lengths were 27.2 mm and 17.1 mm respectively. The buccal root was the larger of the two in 47.7% of teeth and 43.1% had roots of equal size. The lingual root was larger than the buccal root in 9.2% of cases. Clinicians should be aware of the anatomical variation that exists for mandibular canines.

Cuspid↗
PubMed1999

Accuracy of four electronic apex locators: an in vitro evaluation.

In the present study, the accuracy and operator dependency of four electronic canal length measuring devices (Apex Finder AFA Model 7005, Apex-Finder, Neosono Ultima EZ and Apit 2) were compared under a set of specified conditions. The electronic apex locators were tested in unflared dry, flared wet and flared dry canals, and in a gelatin as well as in a sodium hypochlorite sponge model. Fifteen extracted single-canaled teeth were selected. The differences between canal lengths obtained by the electronic apex locators and actual canal lengths were scored. Only the Apex-Finder was found to be unreliable (measurements higher than +/- 0.5 mm from the apical foramen). This device was also found to be particularly dependent on operator. A ranking based on a precision of +/- 0.1 mm from the apical foramen showed the Apex Finder AFA Model 7005 to be the most accurate. Early coronal flaring did not ensure better or more precise readings. The gelatin model was evaluated to be more suitable for testing electronic apex locators in vitro than the sodium hypochlorite model.

Analysis of Variance↗
PubMed1999

Detection and measurement of endodontic root perforations using a newly designed apex-locating handpiece.

Access openings and lateral root perforations were prepared in 40 single-rooted extracted teeth. The distance to the perforations was measured visually and then with the Tri Auto ZX. The electronic device was used first in its apex-locating function and then in conjunction with its automatic reverse mechanism. On average, the electronically measured length was slightly shorter than the visually measured length (P < 0.05). When the automatic reverse mechanism was used, the values registered were either consistent with or slightly different (+/- 0.5 mm) from the electronically measured length (P > 0.05). The results of this study revealed that the Tri Auto ZX detected and measured endodontic root perforations within a range of clinically acceptable variations.

Dental High-Speed Equipment↗
PubMed2004

Bone structure effect on root resorption.

OBJECTIVES: To explore if alveolar bone shape and density might promote external apical root resorption. SETTING AND SAMPLE POPULATION: Panoramic radiographs of 700 patients who had orthodontic treatment at Temple University were reviewed and 22 patients with radiographic evidence of root resorption on the lower incisors were selected for the study. Exclusion criteria included a history of systemic diseases, craniofacial abnormalities, tooth injury, endodontically treated teeth, and impacted teeth. METHODS: Pre-treatment (T1) and post-treatment (T2) cephalometric radiographs were converted into digital format and enhanced to reduce contrast variability and improve edge definition. Tooth length, root length, root area, alveolar area around the root including cortical area, area of medullary bone, and area of the symphysis were measured using an interactive software algorithm. A region of interest within the symphysis was also defined and trabecular space area and fractal dimension calculated as an estimate of bone density. RESULTS: Root area and tooth length were correlated negatively with changes in root area, tooth area, and root length. Larger teeth demonstrated a greater amount of root resorption. Dentoalveolar complex dimensions remained relatively unchanged during tooth movement. The amount of alveolar bone around the root, thickness of cortical bone, density of the trabecular network, and fractal dimension showed no significant correlation with the extent of the external apical root resorption. CONCLUSIONS: The results of this study suggest that the density and morphology of the dentoalveolar complex are not significant factors in the etiology of external apical root resorption.

Adolescent↗
PubMed2004

Incidence and severity of root resorption in orthodontically moved premolars in dogs.

OBJECTIVES: To study treatment-related factors for external root resorption during orthodontic tooth movement. DESIGN: An experimental animal study. SETTING AND SAMPLE POPULATION: Department of Orthodontics and Oral Biology, University Medical Centre Nijmegen, The Netherlands. Twenty-four young adult beagle dogs. EXPERIMENTAL VARIABLE: Mandibular premolars were bodily moved with continuous or intermittent controlled orthodontic forces of 10, 25, 50, 100, or 200 cN according to standardized protocols. At different points in time histomorphometry was performed to determine the severity of root resorption. OUTCOME MEASURE: Prevalence of root resorptions, defined as microscopically visible resorption lacunae in the dentin. Severity of resorption was defined by the length, relative length, depth, and surface area of each resorption area. RESULTS: The incidence of root resorption increased with the duration of force application. After 14-17 weeks of force application root resorption was found at 94% of the root surfaces at pressure sides. The effect of force magnitude on the severity of root resorption was not statistically significant. The severity of root resorption was highly related to the force regimen. Continuous forces caused significantly more severe root resorption than intermittent forces. A strong correlation (0.60 < r < 0.68) was found between the amount of tooth movement and the severity of root resorption. CONCLUSIONS: Root resorption increases with the duration of force application. The more teeth are displaced, the more root resorption will occur. Intermittent forces cause less severe root resorption than continuous forces, and force magnitude is probably not decisive for root resorption.

Analysis of Variance↗
PubMed2004

Characteristics of patients with severe root resorption.

OBJECTIVES: The purpose of this study was to compare a group of patients in whom all four maxillary incisors were resorbed at least 20% with a matched group. MATERIALS AND METHODS: Retrospective, case-control. Root resorption was measured on pre- and post-treatment periapical radiographs collected from 868 patients treated in private practices in southern California. Diagnostic and treatment factors were recorded, and vertical and horizontal apical movement calculated from cephalometric films. Root shape was assessed with a six-object non-parametric rating system. From this patient population, 25 patients were found who had >20% root resorption on all four maxillary incisors. A case control group without severe root resorption matched by sex, treating office, age at start, ethnicity, and duration of treatment was created with two controls for each severe case. RESULTS: There were no statistically significant differences found for extractions, use of Class II and finishing elastics, transverse treatments, overjet, overbite, vertical, tooth length, habits, and root shape. Higher estimated risk was found for abnormal root shape for both maxillary incisors, and tongue thrust. Horizontal apical displacement was not significantly different (p = 0.07) but severely resorbed incisors were retracted an average of one millimeter further. CONCLUSIONS: Twenty-five of 868 patients were found to have over 20% of all four of their maxillary incisors resorbed. This is <3% of the total patients. Matching this group by sex, ethnicity, office, treatment time, and age greatly reduced the number of factors that would differentiate these patients from 50 who did not get severe root resorption. We conclude that horizontal root displacement, tongue thrust, and abnormal root shape may have higher estimated risk but interoffice variability and treatment time cannot be underestimated.

Adolescent↗
PubMed1999

Esthetic smile analysis of maxillary anterior tooth width: the golden percentage.

UNLABELLED: With increasing application of cosmetic dental treatment comes the need for a greater understanding of esthetic principles. Scientific analysis of beautiful smiles has revealed repeatable, objective principles that can be systematically applied to evaluate and improve dental esthetics in predictable ways. Symmetry across the midline, anterior or central dominance, and regressive proportion are three composition elements required to create utility and esthetics in a smile. The Golden Proportion has been suggested as one possible mathematic analysis tool for assessing dominance and proportion in the frontal view of the arrangement of maxillary teeth. It has proven to be controversial in developing esthetically beautiful smiles and cumbersome for evaluating symmetry. CLINICAL SIGNIFICANCE: This article considers a bilateral analysis of apparent individual tooth width as a percentage of the total apparent width of the anterior segment and proposes the concept of the Golden Percentage as a more useful application in diagnosing and developing symmetry, dominance, and proportion for esthetically pleasing smiles.

Cuspid↗
PubMed2000

Small-diameter implants: indications and contraindications.

The choice of implant diameter depends on the type of edentulousness, the volume of the residual bone, the amount of space available for the prosthetic reconstruction, the emergence profile, and the type of occlusion. Small-diameter implants are indicated in specific clinical situations, for example, where there is reduced interradicular bone or a thin alveolar crest, and for the replacement of teeth with small cervical diameter. Before using a small-diameter implant, the biomechanical risk factors must be carefully analyzed. Preliminary reports of this type of implant show good short- and medium-term results.

Alveolar Bone Loss↗
PubMed2002

Restorative and Invisalign: a new approach.

This case report describes an interdisciplinary treatment approach using the Invisalign System (Align Technology, Inc., Santa Clara, California) for orthodontics in combination with restorative dentistry. This combined approach was selected for an optimum esthetic and functional result. This case report demonstrates how a restorative case can be improved with prerestorative orthodontic alignment. The Invisalign System was used for opening the bite anteriorly, space distribution, and midline correction. The restorative dentistry procedures involved veneering to enhance the maxillary incisor length-to-width ratio and provide anterior guidance. The cosmetic alternative treatment modality to conventional fixed orthodontics allowed the clinician to accomplish the prerestorative orthodontic goals to help meet the desires of an esthetically conscientious patient.

Adult↗
PubMed2004

Evaluation of "golden proportion" in individuals with an esthetic smile.

BACKGROUND: One of the most important tasks in esthetic dentistry is creating harmonious proportions between the widths of maxillary anterior teeth when restoring or replacing these teeth. The "golden proportion" is a main guideline introduced in this field. PURPOSE: This study aimed to investigate the existence of the golden proportion between the widths of the maxillary anterior teeth in individuals with an esthetic smile. MATERIALS AND METHODS: This study was conducted with 157 dental students (75 women and 82 men), with ages ranging from 18 to 30 years. Students whose natural smile did not develop any visual tension with regard to the study's and their own criteria were selected as having esthetic smile. An image measurement program was used to measure the apparent mesiodistal widths of six maxillary anterior teeth on the scanned photographs of these subjects. The existence of the golden proportion was investigated in the width ratios of maxillary anterior teeth. RESULTS: The golden proportion was not found to exist between perceived maxillary anterior teeth widths of individuals with an esthetic smile. CONCLUSION: The golden proportion is not a common factor in esthetic smiles. CLINICAL SIGNIFICANCE: This article suggests considering the dentofacial specificities of each individual and also the wide variety of natural teeth proportions when restoring or replacing the maxillary anterior teeth. However, individual cultural characteristics and perception of beauty must be considered.

Adolescent↗
PubMed2005

Managing congenitally missing lateral incisors. Part II: tooth-supported restorations.

Three treatment options exist for the replacement of congenitally missing lateral incisors: canine substitution, a tooth-supported restoration, or a single-tooth implant. Selecting the appropriate treatment option depends on the malocclusion, the anterior relationship, specific space requirements, and the condition of the adjacent teeth. The ideal treatment is the most conservative alternative that satisfies individual esthetic and functional requirements. This article closely examines the three options when replacing a missing lateral incisor with a tooth-supported restoration. These options are a resin-bonded fixed partial denture, a cantilevered fixed partial denture, and a conventional full-coverage fixed partial denture. The specific criteria that must be evaluated for each option is addressed to illustrate the importance of interdisciplinary treatment planning to achieve optimal esthetics and long-term predictability. This article is the second of a three-part series discussing the three treatment alternatives for replacing congenitally missing lateral incisors.

Anodontia↗
PubMed2006

Correlation between facial measurements and the mesiodistal width of the maxillary anterior teeth.

UNLABELLED: One of the most difficult aspects during the selection of maxillary anterior teeth for a removable prosthesis is determining the appropriate mesiodistal width of the six maxillary anterior teeth. Many attempts have been made to establish methods of estimating the combined width of these anterior teeth, and improving the esthetic outcome. The proportion of facial structures and the relationship between facial measurements and natural teeth could be used as a guide in selecting denture teeth. The aim of this study was to verify the relation between the combined mesiodistal width of the six maxillary anterior teeth and the facial segments: the width of the eyes, the inner canthal distance (ICD), the interpupillary distance (IPD), the interalar width, and the intercommissural width (ICm). Standardized digital images of 81 dentate Brazilian subjects were used to measure both facial and oral segments when viewed from the frontal aspect through an image processing program. To measure the distance between the upper canines on a curve, accurate casts were made from the upper right first premolar to the upper left first premolar. The Spearman rank correlation coefficient was conducted to measure the strength of the associations between the variables (alpha = 0.05). The results showed a significant correlation between all facial elements and the combined mesiodistal width of the six teeth, when observed from the frontal aspect. The ICD, IPD, and ICm showed the highest probability of being correlated to the mesiodistal width of the teeth (p = 0.000). CLINICAL SIGNIFICANCE: This article considers facial analysis with digital photography as a practical and efficient application to select the mesiodistal width of artificial anterior teeth in an esthetically pleasing and natural appearance during an oral rehabilitation treatment.

Adolescent↗
PubMed1990

Measurement of the force required to extract the mandibular first molar from its socket in the dissected jaw of growing young rats.

Age-related changes in the mechanical strength of the periodontal ligament have been examined by measuring the force required to extract the mandibular first molar from its socket at an extension rate of 5 mm/min in the dissected jaws of growing young rats from 3 to 32 weeks of age. Almost linear increase in the ultimate loads was found from 3 to 8 weeks of age. However the values from 8 to 32 weeks of age did not show any significant differences. Close correlations were found between the ultimate loads and the weights of animals, mandibles and extracted teeth and between the load and length of the tooth from 3 to 8 weeks of age. It is supposed that a mechanical equilibrium has been established within the periodontal ligament in association with various external and internal factors such as root elongation, alveolar bone growth, turnover and maturation of periodontal ligament and occlusal activity, at about 8 weeks of age in the rat mandibular first molar.

Aging↗
PubMed1990

The effect of age on the mechanical properties of the periodontal ligament in the incisor teeth of growing young rats.

Mechanical properties of the periodontal ligament of the incisor have been examined by pushing the tooth out of its surrounding alveolar bone in sections of the mandibles of rats from 3 to 24 weeks of age. The maximum load, failure energy in shear and elastic stiffness estimated from the load-deformation curves, showed a tendency to increase with age from 3 to 12 weeks but the maximum deformation did not. Age-related changes were not appreciable in all mechanical measures estimated from the stress-strain curves. It is suggested that increases in the maximum load and elastic stiffness from the load-deformation curves with age are closely related to those in the size of teeth or in the area of the periodontal ligament facing cementum. It is also suggested that qualitative and quantitative changes in the supporting tissues or in the collagen fibres/unit area of the periodontal ligament are minor from 3 to 24 weeks of age in the rat mandibular incisor.

Aging↗