Pengaruh Pencabutan Gigi Premolar terhadap Overall Bolton Ratio pada Maloklusi Klas I di RSGMP FKG USU

Abstract

Introduction : In orthodontics treatment,to obtain a good and stable occlusion, there should be an harmony between the combined mesiodistal widths of maxillary teeth and those of mandibular teeth. Extraction of premolars is routinely carried out in orthodontic treatment, but the extraction can lead to the changes of the overall Bolton ratio and the changes are influenced by different extraction combinations. The purpose of this study is to investigate the effects of premolar extraction on the overall Bolton ratio in Class I malocclusion patients. Methods : mesiodistal tooth widths are measured on 40 pretreatment dental casts of subjects with Class I malocclusions with 0,01 mm accuracy digital caliper. The overall ratios and tooth-size discrepancies are determined before and after hypothetical premolar extractions. Before and after extractions, the subjects were divided into small, normal, and large overall ratio groups categorized by the Bolton ± standard deviation definition. Extractions are performed in the following combinations: (1) all first premolars, (2) all second premolars, (3) maxillary first and mandibular second premolars, and (4) maxillary second and mandibular first premolars. Statistical evaluations are carried out using analysis of Oneway ANOVA , Wilcoxon Signed Rank test. Results: The overall ratios decreased after extraction in any combinations of premolars. The subject in Bolton small group are still in small group. Some of the patients in the Bolton normal move into Bolton normal and Bolton small. And most of the Bolton big move into the Bolton normal. Conclusions: The four premolar combination extractionshave significant impact on the overall Bolton ratio. The overall Bolton ratio is decreased after extraction premolar in any combinations extraction.

Pendahuluan ; Dalam perawatan ortodonti, untuk mendapatkan oklusi yang baik dan stabil diperlukan keharmonisan ukuran lebar mesiodistal gigi-gigi maksila dan mandibula. Pencabutan gigi premolar, umum dilakukan dalam perawatan ortodonti, namun pencabutan gigi tersebut dapat berpotensi menyebabkan perubahan overall Bolton ratio, dan perubahan tersebut dipengaruhi oleh pola pencabutan yang berbeda. Tujuan: untuk mengetahui pengaruh pencabutan gigi premolar terhadapoverall Bolton ratiopada maloklusi Klas I.Metode : sebanyak empat puluh (40) model studi malokluai Klasi I diukur lebar mesiodistalnya dengan kaliper digital (akurasi 0.01mm).Overall Bolton ratio ditentukan sebelum dan sesudah pencabutan. Subjek dibagi atas kelompok Bolton kecil, normal dan besarberdasarkan nilai rata-rata dan standar deviasi Bolton. Kemudian dilakukan hypothetical extraction dengan empat kombinsai, yaitu (1) pencabutan 4 gigi premolar pertama, (2) 4 gigi premolar kedua, (3) premolar pertama maksila dan premolar kedua mandibula,dan (4) premolar kedua maksila dan premolar pertama mandibula. Analisis data dilakukan dengan menggunakan uji Oneway ANOVA dan uji Wilcoxon Signed Rank. Hasil : overall Bolton ratio mengalami penurunan setelah pencabutan gigi premolar pada semua kombinasi pencabutan. Kelompok Bolton kecil akan tetap menjadi kecil. Kelompok Bolton normal ada beberapa subjek yang merubah menjadi normal dan kecil, sedangkan kelompok Bolton besar hampir semuanya menjadi nilai Bolton normal. Kesimpulan : ke-empat kombinasi pencabutan premolar berpengaruh signifikan terhadap overall Bolton ratio. Nilai overall Bolton ratio berkurang setelah dilakukan pencabutan pada semua kombinasi pencabutan.