Effect of orthodontic treatment involving first premolar extractions on mandibular third molar angulation and retromolar space

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Abstract

Background

Third molars present more problems than other teeth because they are the last teeth to erupt, and so it is important to assess their development when designing an orthodontic treatment plan. The aim of this study was to compare the angulation of the mandibular third molar and retromolar space before and after orthodontic treatment in cases involving first premolar extraction.

Material and Methods

76 patients, 59 women (77.63%) and 17 men (22.36%), were recruited from the Orthodontics Clinic at Benemérita Universidad Autónoma de Puebla (Mexico). Panoramic radiographs were analyzed before and after orthodontic treatment that included first premolar extractions, measuring retromolar space (RS) and the angles formed by the intersection of the axes of the third and second molar (α) and the intersection of the axis of the mandibular plane and third molar (β).

Results

The data obtained underwent statistical analysis. The angle α and β showed statistically significant differences on the left side in women. In men, only the right side α angle showed significant differences. Retromolar space increased significantly on both sides for both sexes.

Conclusions

Third molar angulation presents different behaviors between men and women, with greater verticalization in women.

Key words:Third molar, retromolar space, orthodontics.

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Most cited references 27

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An improved version of the cervical vertebral maturation (CVM) method for the assessment of mandibular growth.

Tiziano Baccetti, Lorenzo Franchi, James A. McNamara (2002)

The present study aimed to provide a version of the Cervical Vertebral Maturation (CVM) method for the detection of the peak in mandibular growth based on the analysis of the second through fourth cervical vertebrae in a single cephalogram. The morphology of the bodies of the second (odontoid process, C2), third (C3), and fourth (C4) cervical vertebrae were analyzed in six consecutive cephalometric observations (T1 through T6) of 30 orthodontically untreated subjects. Observations for each subject consisted of two consecutive cephalograms comprising the interval of maximum mandibular growth (as assessed by means of the maximum increment in total mandibular length, Co-Gn), together with two earlier consecutive cephalograms and two later consecutive cephalograms. The analysis consisted of both visual and cephalometric appraisals of morphological characteristics of the three cervical vertebrae. The construction of the new version of the CVM method was based on the results of both ANOVA for repeated measures with post-hoc Scheffé's test (P < .05) and discriminant analysis. The new CVM method presents with five maturational stages (Cervical Vertebral Maturation Stage [CVMS] I through CVMS V, instead of Cvs 1 through Cvs 6 in the former CVM method). The peak in mandibular growth occurs between CVMS II and CVMS III, and it has not been reached without the attainment of both CVMS I and CVMS II. CVMS V is recorded at least two years after the peak. The advantages of the new version of the CVM method are that mandibular skeletal maturity can be appraised on a single cephalogram and through the analysis of only the second, third, and fourth cervical vertebrae, which usually are visible even when a protective radiation collar is worn.

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Accuracy of linear and angular measurements on panoramic radiographs taken at various positions in vitro.

M Darendeliler, Joseph P Geenty, Steve Stramotas … (2002)

The accuracy of measurement of tooth length and angulation on dental panoramic tomograms (DPTs) is thought to be highly dependent on head positioning technique. A model representing the dentition and the functional occlusal plane was designed using an acrylic framework and stainless steel wires. The aim was to investigate whether varying the position of the model affects the linear and angular measurements on DPTs. Four different positions were investigated: initial position representing natural head posture (NHP) (T1); lateral right cant of the occlusal plane (T2); lateral left cant of the occlusal plane (T3); and tilting the occlusal plane up anteriorly (T4). On each DPT, four sets of measurements were recorded: (1) Vertical linear measurements of the stainless steel pins and ratio calculations of the 'crown' and 'root' segments (represented by the wire above and below the occlusal plane, respectively); (2) angular measurements of the pins relative to the occlusal plane; (3) angular measurements of the pins relative to a constructed reference line; and (4) angular measurements of pins relative to each other in the same segment. The results showed a significant error (P < 0.05) in all measurements when the occlusal plane was tilted up anteriorly by 8 degrees. A lateral cant of the occlusal plane by less than 10 degrees without an upward anterior rotation showed no significant effect on the measurements. This would suggest that there is some tolerance of variation in head position.

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Precision and accuracy of measurements in digital panoramic radiography.

R. Schulze, F Krummenauer, F Schalldach … (2000)

To evaluate the precision and accuracy of digital measurements in digital panoramic radiography. A series of 70 digital panoramic radiographs were obtained of a dry skull in seven different positions with metallic pins and spheres fixed to the mandible. Three replicate measurements were performed with the mouse-driven cursor by one reader at 1:1 and 2:1 magnification. Precision was assessed with the reliability index (R) and Malony/Rastogi test and the effect of magnification on accuracy by paired Wilcoxon test. Vertical measurements were less reproducible than horizontal measurements. There were significant differences in assessments between images at 1:1 and 2:1 magnification (P < 0.05). The maximum variation in mean difference was 0.4% of actual object length for pins and 1.2% for spheres. The difference did not exceed 0.1 mm. R was lower for 2:1 magnification and consistently lower for spheres compared with pins. The most reliable measurements were obtained of linear objects in the horizontal plane. Digital measurements are sufficiently accurate for clinical use.

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Author and article information

Journal

Journal ID (nlm-ta): J Clin Exp Dent

Journal ID (iso-abbrev): J Clin Exp Dent

Journal ID (publisher-id): Medicina Oral S.L.

Title: Journal of Clinical and Experimental Dentistry

Publisher: Medicina Oral S.L.

ISSN (Electronic): 1989-5488

Publication date (Electronic): 1 March 2017

Publication date Collection: March 2017

Volume: 9

Issue: 3

Pages: e333-e337

Affiliations

[1 ]Master in Orthodontics. Benemérita Universidad Autónoma de Puebla. Puebla, Puebla México

[2 ]Master in Pediatric Dentistry, Professor, Faculty of Dentistry, Benemérita Universidad Autónoma de Puebla, Mexico

[3 ]PhD, D. Master in Oral Prosthodontics and Specialist in Oral Rehabilitation. Professor, Faculty of Dentistry, University of Veracruz, Mexico

[4 ]PhD in Dentistry. Master in Orthodontics UV. Associate Professor, Faculty of Medicine and Dentistry, University of Valencia, Spain

[5 ]PhD in Dentistry. Master in Orthodontics UCM. Professor, Faculty of Medicine and Dentistry, University of Valencia, Spain

Author notes

Reforma Sur 3160. int. 303 col. La Paz. C.P. 72000 Puebla, Puebla. México , E-mail: luxmg13@ 123456icloud.com

Conflict of interest statement:The authors have declared that no conflict of interest exist.

Article

Publisher ID: 53434

DOI: 10.4317/jced.53434

PMC ID: 5347277

PubMed ID: 28298970

SO-VID: c4240a3b-573b-4dbe-b910-0c9d12321e30

License:

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Effect of orthodontic treatment involving first premolar extractions on mandibular third molar angulation and retromolar space

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Abstract

Background

Material and Methods

Results

Conclusions

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Most cited references 27

An improved version of the cervical vertebral maturation (CVM) method for the assessment of mandibular growth.

Accuracy of linear and angular measurements on panoramic radiographs taken at various positions in vitro.

Precision and accuracy of measurements in digital panoramic radiography.

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Journal

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Author notes

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