---

Background and purpose: Preventive orthodontics in mixed dentition requires accurate prediction for mesiodistal width of unerupted permanent teeth. In this study, we presented a software for prediction of unerupted permanent canine and premolar mesiodistal width that help orthodontist in precise treatment planning. Material and Methods: For this cross-sectional study, we scanned alginate impression of 60 subjects (30 males, 30 females) by HP optic scanner for producing digital dental cast. The mesiodistal dimensions of teeth on digital casts were measured. The actual tooth measurements were then compared with predicted values using the Sanin and Savara table (S&S) with reference to special tooth such as incisors and molars in each comparison. Subsequently, the new regression equations were tested in a group of 60 individuals to determine their validity. Finally, we defined the best dental reference and regression equation for software . Results: The presented software has potential for accurate space analysis in premolar and canine area. By using y= 0.706+2.153 x equation, canine and premolar size in Sanin & Savara table is very close to our measurement in Iranian subject. In gender difference, there is no significant difference between male and female. Conclusion: Lower central incisor is most accurate reference for premolar and canine size prediction. Canine is more predictable than premolar and also upper arch than lower arch.

---

Background and purpose: Assessment of tooth length has an important role in success and failure of dental treatments. As yet periapical radiography has been used for the assessment of tooth length causing high x-ray exposure, long time and patient discomfort. Using panoramic radiography can resolve these problems. The major disadvantage of panoramic radiography is monotonous magnification. The aim of this study was to assess the relationship between real and panoramic tooth lengths. Materials and methods: In an analytical study, 89 teeth consisting 59 maxillary first premolars and 30 maxillary second premolars from patients referring to orthodontic clinics of babol were selected. According to universal numbering system the teeth were divided into four groups: T14, T24, T15, T25. Measurements of real and panoramic tooth length were accomplished by a digital caliper. Length linear regression model analysis was used for the prediction of tooth. Results: Real and panoramic tooth lengths and their magnification showed significant differences between two sexes (P< 0.05). For each gender regression models were produced: (male first premolar tooth length= 0.818X+3.017) (female first premolar tooth length= 0.852X+1.875) (male second premolar tooth length= 1.030X-2.028) (female second premolar tooth length= 1.020X-2.246). Conclusion: Using panoramic radiography for estimation of maxillary premolar real tooth length in studied machine is practical and reliable.

---

Background and purpose: The purpose of mechanical cleaning of the root canal is to clean the canal walls, create a conical shape to facilitate access, effective washing, and filling all areas of the root canal. Errors such as root canal transportation are cuased by excessive dentin removal from the canal. The objective of this study was to investigate root canal transportation by a BT Race rotary and manual file with Cone Beam Computed Tomography (CBCT).
Materials and methods: An Ex-vivo study was conducted in 54 extracted first molars. Root curvature was measured by Schneider's method. Preparation was performed in two groups (n= 27 per group) with manual and rotary files. CBCT images were prepared pre and post instrumentation of the canals. SPSS 18 Software was used to measure the amount of canal transportation.
Results: The mean differences of canal transportation between the two groups were 0.24 ± 0.16, 0.19 ± 0.13mm, and 0.17± 0.12mm at T1 (1 mm from apical foramen), T2 (2 mm from apical foramen), and T3 (3 mm from the apical foramen), respectively. The total deviation was 0.022mm in this study. The rotary and manual files at T1 (P=0.51) and T3 (P=0.57) were not significantly different in causing transportation but T2 was found to cause significant canal transportation (P=0.027).
Conclusion: The average canal transportation in 2mm canal from the apical foramen by manual files was lesser than the rotary files. BT race and K-flexo file instruments can preserve the curvature of the root canals. Therefore, both systems can be used in clinical settings with minimal apical transportation.

---

Correction to: An Ex vivo Analysis of Apical Transportation in Root Canals Prepared with BT Race Rotary and Hand K-Flexofile by Cone Beam Computed Tomography
 
Abbas Mesgarani¹,
Azadeh Zakariaie²,
Azam Haddadi Kohsar¹,
Sina Haghanifar3,
Jamshid Yazdani Charati4,
Arman Ebrahimi^5
 
1 Assistant Professor, Department of Endodontics, Faculty of Dentistry, Mazandaran University of Medical Sciences, Sari, Iran
² Resident of Oral and Maxillofacial Radiology, School of Dentistry, Isfahan (khorasgan) Branch, Islamic Azad University, Isfahan, Iran
³ Professor, Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Babol University of Medical Sciences, Babol, Iran
⁴ Professor, Department of Biostatistics, Health Sciences Research Center, Addiction Institute, Mazandaran University of Medical Sciences, Sari, Iran
⁵ Resident of Oral and Maxillofacial Surgery, School of Dentistry, Isfahan (khorasgan) Branch, Islamic Azad University, Isfahan, Iran
 
 
 
 

In the article published in volume 30, issue 185, 2020, the the academic rank and affiliation for the Jamshid Yazdani Charati was published incorrectly, which is now corrected.
 
 
 

J Mazandaran Univ Med Sci 2020; 30(188): 203-204 (Persian).