Effects of Third Molars on Anterior Crowding and Relapse After Orthodontic Treatment

Year 2023, Volume: 5 Issue: 3, 188 - 194, 27.12.2023

Kevser Kurt Demirsoy , Hilal Yılancı , Feridun Abay , S. Kutalmış Büyük

https://doi.org/10.51122/neudentj.2023.76

Abstract

Purpose: This study aimed to evaluate the effect of the absence or presence of third molars on the relapse of mandibular incisor crowding after orthodontic treatment and to determine the indication for prophylactic third molar extraction in orthodontic patients based on Ganss ratios.
Material and Method: The study was conducted with the dental models, panoramic and lateral cephalometric radiographs, and intraoral and extraoral photographs of 42 patients (26 females, mean age 16.56±4.96 years; 16 males, mean age 17.52±4.39 years). Data were collected at three time points: before (T1), at the end of (T2), and at least 2 years after the end of orthodontic treatment (T3). The patients were divided into two groups: those with impacted or erupted third molars (Group 1, n=22) and those with agenesis or extracted third molars (Group 2, n=20). Panoramic radiographs were used to determine the presence or absence of third molars at the three time points and to calculate Ganss ratio (GR) (1). Dental models were scanned with the 3 Shape TRIOS oral scanner (3 Shape Co. Copenhagen, Denmark) and mandibular anterior crowding was assessed using Little’s Irregularity Index (LII) (2). Mann-Whitney U test was used to compare mandibular LII values between the groups. GR values of mandibular impacted third molars at T1-T3 were evaluated with repeated-measures ANOVA. Pearson correlation analysis was used to determine the correlation between LII and GR in Group 1. Statistical significance was set at P<0.05.
Results: There was no statistically significant difference between the groups in terms of the relapse of mandibular anterior crowding and the presence or absence of mandibular third molars (P=0.940). In Group 1, GR increased significantly at T3 due to an increase in retromolar distance (P<0.05). There was no correlation between LII and GR in Group 1.
Conclusion: The presence or absence of mandibular third molars did not affect the relapse of mandibular anterior crowding in orthodontic patients. Prophylactic third molar extraction after orthodontic treatment does not seem necessary.

Keywords

Third molar, anterior crowding, orthodontic treatment, Little’s Irregularity Index, Ganss ratio

Ortodontik Tedavi Sonrası Üçüncü Molar Dişlerin Anterior Çapraşıklık ve Relaps Üzerine Etkilerinin Değerlendirilmesi

Abstract

Amaç: Bu çalışmanın amacı, ortodontik tedavi sonrası üçüncü molar dişlerin varlığının mandibular kesici diş çapraşıklığı üzerine etkisini değerlendirmek ve gömülü üçüncü molar dişlerden elde edilen Ganss oranları ile ortodontik hastalarda profilaktik üçüncü büyük azı dişlerinin çekim endikasyonunu belirlemektir.
Gereç ve Yöntem: Bu çalışmanın materyalini 42 hastanın (26 kadın, ortalama yaş: 16.56±4.96; 16 erkek, ortalama yaş:17.52±4.39) dental alçı modelleri, panoramik ve lateral sefalometrik radyografileri ile ağız içi ve ağız dışı fotoğrafları oluşturdu. Veriler üç aşamada analiz edildi; T1: ortodontik tedavi öncesi, T2: ortodontik tedavi bitimi, T3: ortodontik tedavinin bitiminden en az 2 yıl sonra. Çalışma grupları; Grup 1: üçüncü molar dişleri gömülü veya sürmüş olan hastalar (22 hasta). Grup 2: üçüncü molar dişleri hiç oluşmamış veya çekilmiş olan hastalar (20 hasta). Panoramik radyografiler, T1, T2 ve T3 dönemlerinde üçüncü molar dişlerin varlığını veya yokluğunu tespit etmek ve Ganss oranının (GR) değerlendirilmesi için kullanıldı (1). T1, T2 ve T3 aşamalarında alınan diş modelleri 3 Shape TRIOS oral tarayıcı (3 Shape Co. Kopenhag, Danimarka) ile tarandı ve mandibular anterior çapraşıklık Little's Irregularity Index (LII) (2) ile ölçüldü. Mandibular LII karşılaştırması için Mann Whitney U testi kullanıldı. Mandibular gömülü üçüncü molarların T1-T3 GR'si tekrarlı ölçümler ANOVA testi ile değerlendirildi. İstatistiksel anlamlılık P<0.05 olarak belirlendi.
Bulgular: Mandibular anterior çapraşıklığın nüksetmesi ve mandibular üçüncü molarların varlığı veya yokluğu açısından gruplar arasında istatistiksel olarak anlamlı fark yoktu (P=0.940). Grup 1’de GR, retromolar mesafedeki artışa bağlı olarak T3 döneminde istatistiksel olarak anlamlı derecede arttı (P<0.05). Grup 1’de LII ve GR arasında anlamlı korelasyon bulunmadı.
Sonuç: Ortodontik tedavi görmüş hastalarda mandibular anterior çapraşıklık nükslerinde mandibular üçüncü molarların varlığı veya yokluğu etkili değildir. Ortodontik tedaviden sonra profilaktik üçüncü molar diş çekimi zorunlu görünmemektedir.

Keywords

Üçüncü molar, anterior çapraşıklık, ortodontik tedavi, Little, Ganss oranı

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