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At least 1,117 records · Page 62Linked to original sources
PubMed1996

When to use fillers, build-ups or posts and cores.

After preliminary tooth preparation for crowns, all previously placed tooth restorative material should be removed from teeth before making final tooth preparations. Small areas of missing teeth should be replaced with fillers (compomer); larger pieces of missing teeth should be replaced with build-ups (bonded composite resin or bonded amalgam); and endodontically treated teeth with half or more of the coronal tooth structure missing should receive a titanium or titanium alloy post and core and a bonded composite resin or bonded amalgam build-up.

Compomers↗
PubMed2004

Lingual flap retraction for third molar removal.

PURPOSE: Lingual nerve damage following lower third molar surgery remains a clinical problem. The traditional approach in the United States has been a buccal approach avoiding exposure or surgery on the lingual side of the crest of the ridge. An alternative technique is to deliberately expose the lingual tissues and retract the lingual nerve lingually before tooth removal. This study reports a trial of this technique. MATERIALS AND METHODS: Patients had removal of their lower third molars carried out using a technique that raises a lingual flap in addition to a buccal flap and places a specially designed lingual retractor to ensure that the lingual nerve is held out of the surgical field. This technique was used in cases where the crown of the tooth had to be sectioned or when distal bone needed to be removed. RESULTS: Two hundred fifty patients were treated by this method. There were 4 cases of transient lingual paresthesia, presumably caused by traction pressure from the retractor. Three of these cases were mild and resolved within 3 weeks. The fourth case had more profound paresthesia, but still resolved within 2 months. There were no cases of permanent nerve damage, and in many cases removal of the third molar was simplified by the superior access. CONCLUSION: Lingual retraction for third molar removal improves access to the surgical site and can simplify third molar removal. In this prospective study there were no cases of permanent lingual nerve injury.

Alveolectomy↗
PubMed2006

Flaws in root resorption assessment algorithms: role of tooth shape.

INTRODUCTION: The purposes of this study were to analyze and critique the mathematical algorithms used in the clinical assessment of root resorption. METHODS: Geometric constructions and derived mathematical expressions were used to investigate the influence of tooth shape on the relationships between tooth, root, and crown lengths and their respective sizes as measured on before and after radiographs. results: The ambiguities of root-loss assessment protocols are demonstrated. CONCLUSIONS: Root resorption assessment algorithms are unsuited for their intended applications.

Algorithms↗
PubMed2002

Supernumerary teeth in the primary dentition: a report of two cases.

Supernumerary teeth occur frequently in the permanent dentition, but they are rare in the primary dentition. Mesiodens is a supernumerary tooth with a cone shaped crown and a short root. The supernumerary tooth which bears resemblance to the tooth with which it is associated is called a supplemental tooth. The etiology of supernumerary teeth is still unknown and not well understood. Radiographic examination of pre-school children is essential for their diagnosis. Early removal of these teeth is required so that complications such as delay in eruption of permanent teeth, crowding, diastema, rotations and certain pathologic conditions can be averted.

Child, Preschool↗
PubMed2005

The relationship between number of striae of Retzius and their periodicity in imbricational enamel formation.

Imbricational crown formation times (ICFTs) estimated from the number of perikymata on tooth surfaces are error-prone because the number of days between adjacent perikymata varies across individuals and species, and is only visible within tooth microstructure. We investigated striae of Retzius (SR) numbers (analogous to perikymata numbers), SR periodicities (days between SR or perikymata), and ICFTs for a mandibular canine sample (n=49) from medieval Denmark. We tested the relationship between SR number and periodicity to determine whether regression formulae could be produced that would allow periodicity (and ICFTs) to be determined from surface perikymata numbers. Periodicities (range=7-11 days, mode=8) and SR numbers (range=142-257, mean=190.3, s.d.=27.5) were normally distributed; ICFTs were non-normal (mean=1,594 days, s.d.=65.7). We tested periodicity as a quadratic, linear, and log-log transform linear function of SR number and found an inverse relationship (quadratic: R2=0.9504; linear: R2=0.9138; log-log transform: R2=0.9418; all p<0.001) that allowed estimation of periodicity from SR or perikymata numbers in this population and tooth type. If periodicity and SR number are inversely related in other hominin taxa, studies that have estimated ICFT by multiplying perikymata number by a human modal periodicity value or made inferences about development based only on perikymata numbers may have introduced substantial error into their ICFT estimates and life history inferences. The inverse relationship is similar to that predicted by a model of SR formation in which the ICFT for a given tooth type and population is held constant and all combinations of periodicity and SR number result in the same ICFT. However, we found that lower periodicities had longer ICFTs and higher periodicities had shorter ICFTs than the model predicted, suggesting that the model may not reflect the real process, or that there are other factors (e.g., sample size, misclassification, sexual dimorphism) also affecting the relationship between periodicity and SR number.

Adolescent↗
PubMedDate not supplied

Finite element analysis studies of a metal-ceramic crown on a first premolar tooth.

PURPOSE: This study examined the stresses developed during loading in a first premolar metal-ceramic crown made of different metal cores, and used them to anticipate the locations and form of the most likely failure modes. The maximum principal stresses in the porcelain are indicators of fracture, and the von Mises stresses in the metal core are indicators of the location of yielding. MATERIALS AND METHODS: Two-dimensional axisymmetric models with different core metals were analyzed using finite element analyses. An axial load of 600 N was applied vertically downward, over a circular area around the crown's fissure. RESULTS: The peak maximum principal tensile stress in the porcelain existed on the surface of the crown, partially outside the cusp, with the greatest peak in the gold-porcelain system (15.8 MPa). An inverse relationship between the peak maximum principal tensile stress of each system and the elastic modulus of each core material was found. According to evaluation of the critical flaw size for each system, even a crack completely through the thickness of the porcelain was not critical. The maximum von Mises stress existed in the metal coping, on the radial edge at the axial/occlusal line angle, with the highest maximum in the nickel-chromium system (143.9 MPa). There existed a proportional relationship between the maximum von Mises stress in each metal and their respective elastic moduli. All maximums were well below the yield strength of the metal alloys used. CONCLUSION: A greater understanding of the influence of an axial load on the resulting stresses has been achieved, showing that the phenomena of fracture and yielding are unlikely for the crown experiencing this axial load.

Bicuspid↗