Comparison of the effect of premolar extraction and non-extraction on the position and developmental changes of the lower third molars

Effect of orthodontic extraction of mandibular premolars on third molar angulation after treatment with fixed appliances : A cross-sectional study

PURPOSE

Orthodontic treatment involving premolar extractions might improve the angulation of lower third molars, which are the teeth most often impacted. This study analyzes the impact of first/second lower premolar extraction during orthodontic therapy on the angulation of mandibular third molars.

METHODS

A total of 120 patients treated non-extraction (n = 40), with extraction of first (n = 40), or second lower premolars (n = 40) were included. The mesiodistal angulation of lower third molars relative to the adjacent tooth and their developmental stage were evaluated from posttreatment orthopantomograms. Between-group differences were statistically evaluated at a significance level of 0.05.

RESULTS

The orthopantomograms of 120 patients (51% female) with a median age of 15.2 years at the time of debonding were evaluated after a mean treatment duration time of 2.9 years. No difference (P > 0.05) was seen between the average angulation of the lower third molars of the right (mean = 24.4°, standard deviation [SD] 13.6°) and the left side (mean = 23.6°, SD 14.1°). No differences in the angulation of the lower third molar were found between the non-extraction and extraction groups for the right (P = 0.44) or the left side (P = 0.22). Likewise, no differences were found when comparing the first and second premolars for the right (P = 0.26) or the left side (P = 0.10). Premolar extraction was associated with an advanced root development stage of the right third molar (odds ratio 7.1; 95% confidence interval 1.1-48.1; P = 0.04), with no differences between extraction of the first or second premolar (P = 0.10).

CONCLUSION

Orthodontic treatment involving premolars extractions might be associated with a small acceleration in root development, but not with the angulation, of lower third molars.

Evaluation of clinical and radiographic warning signs for prediction of oroantral communication following tooth extractions

OBJECTIVES

Oroantral communication (OAC) is a relatively common and mild complication of maxillary tooth extractions. Preoperative prediction of OAC can reduce treatment duration and prepare both operators and patients for the procedure. This study aims to identify alarming radiographic and clinical indicators that can predict OAC therefore assisting clinical decision making to practicing general dentists.

METHODS

In this retrospective case-control study the OAC group consisting of 97 cases and a control group twice the size was established. Clinical data were collected, and measurements were conducted separately by two blinded observers on digital panoramic radiographs. Inter-rater reliability was assessed. In case of disagreement a third observer's results were utilized. The correlation between OAC and demographic data (age, sex), as well as various factors assessed on panoramic radiographs (including, but not limited to, the length of the root, root projection into the sinus, bone width, presence of mesial and distal adjacent teeth), was statistically evaluated.

RESULTS

Inter-rater reliability was found to be excellent. Several factors were identified as potential predictors of OAC. According to our model, the strongest predictors were the distance between the cemento-enamel junction and marginal bone, extent of root projection into the sinus, presence of sinus recess around the roots, angulation, and absence of the mesial adjacent tooth.

CONCLUSIONS

Well-defined measurements on panoramic radiographs may aid in predicting OAC. Further prospective investigations are necessary to confirm these indicators and address factors related to clinical examination and operation.

CLINICAL RELEVANCE

We present several clinical and radiographic warning signs of OAC that can facilitate pre-extraction decision-making.

Evaluation of pharyngeal airway dimensions and cephalometric changes after premolar extraction and nonextraction orthodontic treatment in adolescent and adult patients

PURPOSE

The purpose of this study was to investigate the effects of premolar extraction and non-extraction for orthodontic treatment on the skeletal, dentoalveolar and pharyngeal airway.

MATERIAL AND METHOD

The study was carried out with the radiographs of a total of 130 patients at the ages of 14 to 25, including 59 male and 71 female patients. The cases were divided into two groups as the "extraction" group(2 upper premolar teeth) (n = 66) and the "non extraction" group (n = 64).

RESULTS

Extraction Group:In both age groups, there was a statistically significant increase in the mean interincisal angle (U1xL1) and lower anterior facial height (ANS-Me) values(p < 0.05). In the 14-18 age group, there was a significant increase in the mean upper airway thickness, inferior airway space, hyoid position, soft palate length(PNSP) and upper pharynx values(p < 0.05). In both sexes, while the mean U1xL1 and ANS-Me values significantly increased, the mean upper incisors inclination values decreased significantly(p < 0.05). Non Extraction Group:In both age groups, the mean ANS-Me values increased significantly from T0 to T1(p < 0.05). In the 14-18 age group, the increase in the mean upper adenoid thickness, tongue length,PNSP, softpalate thickness and vertical airway length values was significant(p < 0.05). In the male patients, the mean U1xL1 value decreased significantly(p < 0.05).

CONCLUSION

The premolar teeth extraction performed in the patients receiving orthodontic treatment did not affect airway dimensions to a high extent.It was determined that the position of the hyoid bone and tongue length was not affected in the patients with premolar extraction and non extraction.

Evaluation of the airway space changes after extraction of four second premolars and orthodontic space closure in adult female patients with bimaxillary protrusion - A retrospective study

Background & objectives

Previous studies have found that first premolar extractions during orthodontic treatment may alter the upper airway dimensions. The objective of this study is to investigate the effects of second premolar extraction during orthodontic treatment on the dimensions of the upper airway in a sample of female adults.

Methods

Twenty-nine female adult patients with ages between 18 and 30 years old and incisor bimaxillary protrusion were included in this study. They were treated with comprehensive orthodontic treatment which included the extraction of four second premolars. Pre and post cephalometric radiographs were analyzed using Dolphin imaging software for changes in tongue length and height, soft palate thickness and length, the superior, middle, and inferior airway space, and vertical airway length. Descriptive statistics were used to characterize measurements. Student’s paired t-test was preformed to compare the pre- and post-test mean values of the dimensions.

Results

A significant increase in the vertical airway length was observed after the extraction of the second premolars (p = 0.02). The soft palate length showed a tendency towards an increase that did not reach statistical significance (p = 0.053). No other significant changes in the airway soft tissue measurements were observed. The proclination and protrusion of the upper and lower incisors were significantly decreased compared to pre-treatment measurements.

Interpretation & conclusions.

Orthodontic treatment involving the extraction of all four second premolars in females with bimaxillary protrusion increases the vertical airway length, which is the amount of distance between base of the tongue and posterior nasal spine. No other significant alterations in the upper airway measurements were observed.