A cone-beam computed tomography study of the root and canal morphology of maxillary premolars / 口腔疾病防治

Objective @# To study root morphology, the incidence of three root canals and the root canal anatomy of maxillary premolars.@*Methods@#The cone-beam computed tomography (CBCT) data of 779 maxillary first premolars and 728 maxillary second premolars were collected from 412 patients in Zhuhai Stomatological Hospital. The root and canal morphology, incidence of three canals, bilateral symmetry and location of root canal bifurcation were analyzed. @*Results @#The incidence of three canals in the maxillary first premolars was 1.8% and that in the maxillary second premolars was 0.3%. The incidence of three canals in the maxillary first premolars was significantly higher than that in the maxillary second premolars (c2=8.304, P=0.004). The symmetrical ratio of the three-canal maxillary first premolar was 27.3%. There was no symmetrical three-canal maxillary second premolar. The anatomical morphology of the maxillary premolar can be single root, double root or trident root. Its internal root canal system is complex and diverse. There are seven kinds of Vertucci morphology: the first maxillary premolar is mainly Vertucci IV type, and the second maxillary premolar is mainly Vertucci I type. Most of the root canal bifurcations of the three-canal maxillary premolars were observed in the midthird or the cervical third of the root. All three-canal maxillary premolars had three independent apical foramens. @*Conclusion @#The root canal morphology of maxillary premolars is complex and changeable. CBCT plays an important role in the discovery of variation and extra root canals.

A case of maxillary second premolar with 3 teeth and 4 root canals and a literature review / 口腔疾病防治

Objective @#To explore the discovery and treatment of multiple root canals in the maxillary second premolar to provide a reference for root canal therapy.@*Methods @#A case of maxillary second premolar occlusal discomfort accompanied by cold and heat stimulation pain and spontaneous pain was analyzed retrospectively.@*Results@# In this case, the number of roots and root canals in the tooth was determined by CBCT to be three roots with four canals. Root canal therapy was performed with Ni-Ti endodontic files and thermoplastic gutta-percha via root optical microscopy. The clinical symptoms disappeared after the operation.@*Conclusion@#The maxillary second premolar root canal system is complex, and additional root canals can be found and located with CBCT and optical microscopy. High-quality root canal therapy was completed.

Root Canal Treatment of Three - Rooted Maxillary Second Premolar Done by Undergraduate Dental Student - A Case Report.

The possibility of a three rooted maxillary second premolar is extremely rare; diagnosis and treatment of such cases is challenging especially for undergraduate dental students. The aim of this report is to present a root canal treatment of a very rare case of a three rooted upper maxillary second premolar tooth done by an undergraduate dental student. The tooth was diagnosed as acute irreversible pulpitis. Visually the tooth morphologically looked as a normal premolar but radiographically revealed anatomical variations of three roots. Access cavity was opened carefully; three canals were detected, negotiated, biomechanically prepared and obturated by cold gutta percha lateral condensation technique. The tooth is now completely asymptomatic for almost five months and will be both clinically and radiographicaly monitored bimonthly. A correct radiographic and clinical examination based on knowledge of anatomical variation of this tooth is necessary for successful treatment and better prognosis. Under direct supervision, undergraduate clinical students can perform root canal treatment of difficult cases.

Transient thermal and stress analysis of maxillary second premolar tooth using an exact three-dimensional model.

Aim : In this paper, the temperature and stress distributions in an exact 3D-model of a restored maxillary second premolar tooth are obtained with finite element approach. Objective : The carious teeth need to restore with appropriate restorative materials. There are too many restorative materials which can be used instead of tooth structures; since tooth structures are being replaced, the restorative materials should be similar to original structure as could as possible . Materials and Methods : In the present study, a Mesial Occlusal Distal (MOD) type of restoration is chosen and applied to a sound tooth model. Four cases of restoration are investigated: two cases in which base are used under restorative materials and two cases in which base is deleted. The restorative materials are amalgam and composite and glass-inomer is used as a base material. Modeling is done in the solid works ambient by means of an exact measuring of a typical human tooth dimensions. Tooth behavior under thermal load due to consuming hot liquids is analyzed by means of a three dimensional finite element method using ANSYS software. The highest values of tensile and compressive stresses are compared with tensile and compressive strength of the tooth and restorative materials and the value of shear stress on the tooth and restoration junctions is compared with the bond strength. Also, sound tooth under the same thermal load is analyzed and the results are compared with those obtained for restored models. Results : Temperature and stress distributions in the tooth are calculated for each case, with a special consideration in the vicinity of pulp and restoration region. Numerical results show that in two cases with amalgam, using the base material (Glass-ionomer) under the restorative material causes to decrease the maximum temperature in the restorative teeth . In the stress analysis, it is seen that the principal stress has its maximum values in composite restorations. Conclusion : The maximum temperatures are found in the restoration case of amalgam without base. Besides, it is found that restoration has not any influence on the stress values at DEJ, such that for all cases, these values are close to sound tooth results.

Three root canals in the maxillary second premolar.

In this study, we report an endodontic treatment of the maxillary second premolar with three root canals and distinct foramens. The possibility of three root canals in this tooth is quite small; however, it must be taken into account in clinical and radiographic evaluation during endodontic treatment. Many times, their presence is noticed only after canal treatment due to continuing post-operative discomfort.

Effects of occlusal load on the cervical stress distribution: A three-dimensional finite element study / 대한치과보존학회지

The objective of this study was to investigate the effects of various occlusal loads on the stress distribution of the buccal cervical region of a normal maxillary second premolar, using a three dimensional finite element analysis (3D FEA). After 3D FE modeling of maxillary second premolar, a static load of 500N of three load cases was applied. Stress analysis was performed using ANSYS (Swanson Analysis Systems, Inc., Houston, USA). The maximum principal stresses and minimum principal stresses were sampled at thirteen nodal points in the buccal cervical enamel for each four horizontal planes, 1.0 mm above CEJ, 0.5 mm above CEJ, CEJ, 0.5 mm under CEJ. The results were as follows 1. The peak stress was seen at the cervical enamel surface of the mesiobuccal line angle area, asymmetrically. 2. The values of compressive stresses were within the range of the failure stress of enamel. But the values of tensile stresses exceeded the range of the failure stress of enamel. 3. The tensile stresses from the perpendicular load at the buccal incline of palatal cusp may be shown to be the primary etiological factors of the NCCLs.