Volumetric and morphologic changes due to effect of unilateral extraction of teeth

Abstract

Objective: Chewing includes the rhythmic movement of the jaw muscles. In this study, we investigated volumetric changes in the masticatory muscles and morphometric changes in the mandibular condyle due to unilateral extraction of the teeth in the sixth and twelfth weeks of life. Materials and Methods:Eighteen rats were used. The rats were divided into three groups. In the experimental groups (Groups I and II), all of the teeth on one side of the upper and lower jaws of the rats were extracted. In the control group all the teeth were intact. Volumetric changes of the masseter and temporal muscles were evaluated. In addition, morphometric changes of the mandibular condyle were investigated. Results:The measurements performed six weeks after tooth extraction did not reveal any difference in the temporal muscles between the two sides, however the volume of the masseter muscle on the side of the extraction was significantly reduced (Group I). Twelve weeks after the tooth extraction, the volumes of the masseter and temporal muscles showed significant reduction on the side of the extraction (Group II). A morphometric reduction in the mandibular condyle was observed in the longer period of time. No asymmetry was observed either for muscular volumes or for mandibular condyle dimensions in the control group. Conclusion:Unilateral tooth loss may cause volumetric reduction in the masseter and temporal muscles ipsilaterally. However, the cause of the morphometric reduction in the mandibular condyle on the contralateral side in the longer period of time is surprising. Bulgular: Diş çekimi sonrası altıncı haftada m. temporalis volümünde her iki taraf arasında bir farklılık gözlenmezken, diş çekimi yapılan tarafta m. masseter volümü diğer tarafa göre anlamlı derecede azalmıştır (Grup I). Diş çekimi sonrası onikinci haftada, diş çekimi yapılan tarafta her iki kas volümünde azalma gözlenmiştir (Grup II). Ayrıca, Grup II'de tek taraflı diş kaybının, karşı tarafta condylus mandibula boyutlarında azalmaya neden olduğu gözlenmiştir. Kontrol grubunda ise her iki kas volümlerinde ve condylus mandibula boyutlarında iki taraf arasında fark gözlenmemiştir.Sonuç: Tek taraflı diş kaybı, uzun zaman süreci içerisinde aynı tarafta m. masseter ve m. temporalis volumünde azalmaya neden olur. Ayrıca, aynı grupta, tek taraflı diş kaybının nedeni karşı tarafta condylus mandibula boyutlarında azalmaya neden olması şaşırtıcıdır.

Mandibular condyle changes in rats with unilateral masticatory function

“…Soft diet and molar extraction are conditions leading to a lower masticatory function. 12,19,20 Although it has not been verified in this study, based on other studies, [20][21][22][27][28][29]32 we assumed that extracting the maxillary right molars of young and adult rats could create a unilateral masticatory function, which in turn could cause changes to the condylar process.…”

“…Young and adult rats have been used in several studies that aimed to compare condylar changes in animals with symmetrical and asymmetrical functional load. Soft diet and molar extraction are conditions leading to a lower masticatory function 12,19,20 . Although it has not been verified in this study, based on other studies, 20–22,27–29,32 we assumed that extracting the maxillary right molars of young and adult rats could create a unilateral masticatory function, which in turn could cause changes to the condylar process.…”

“…Tooth loss also has an effect on the mandibular growth process. Molar extractions affect the masticatory function of rats, decreasing the mandibular and condylar head size, 19 , 20 , 21 , 22 but the relationship between unbalanced occlusal support and condylar process development remains to be investigated.…”