Stability of hard tissue profile after mandibular setback in sagittal split osteotomies: a longitudinal and long-term follow-up study

Abstract

The aim of the study was to conduct a long-term follow-up on the stability of the hard tissues after bilateral sagittal split osteotomy (BSSO) with rigid internal fixation (RIF)to set back the mandible and to compare it with that of mandibular advancement performed by the same team of surgeons and with the same examination protocol. Seventeen consecutive patients (6 females and 11 males) could be re-examined 12.7 years (T5) after surgery. The previous examinations were before surgery (T1), 5 days (T2), and 6.6 (T3) and 14.4 (T4) months after surgery. Lateral cephalograms were traced by hand, digitized, and evaluated with the Dentofacial Planner software program. The x-axis for the system of co-ordinates ran through sella (point zero) and the line nasion-sella-line minus 7 degrees. The program determined the x- and y-values of each variable and the usual angles and distances. The effects of treatment were determined with Wilcoxon matched pairs, signed ranks test, with Bonferroni adjustment, and the relationship between variables with Spearman rank correlation coefficient. Relapse at point B was 0.94 mm or 15 per cent and at pogonion 1.46 mm or 21 per cent of the initial setback at T5. Relapse was mainly short-term (T4-T2), 13 per cent for point B and 17 per cent for pogonion. Gender correlated significantly with relapse (T5-T2) at point B (P = 0.002) and pogonion (P = 0.021), i.e. females in contrast to males showed further distalization of the mandible instead of relapse. No correlations were seen for age or the amount of surgical setback. The long-term results in mandibular setback patients were more stable when compared with the mandibular advancement patients examined previously. The initial soft tissue profile, the initial growth direction, and the remodelling processes of the hard tissues must be considered as reasons for long-term relapse. Growth direction positively influenced the long-term results in females: further distalization of the mandible occurred.

Factors Effecting The Relapse in Orthognathic Surgery

“…31 Maksiller gömme ve mandibuler ilerletme cerrahisinde ve mandibuler geriletme cerrahisinde hareket miktarıyla relaps arasında ilişki olmadığı bildirilmiştir. 20,32,33 Benzer şekilde maksiller aşağı konumlandırma miktarı ile cerrahi sonrası vertikal maksiller stabilite arasında da bir ilişki bulunmamıştır. 24 …”

“…50 Maksillanın aşağı hareketinde fiksasyon tipi, greft ve alloplastik materyal kullanımının stabilite üzerindeki etkisinin araştırıldığı bir çalışmada en az relapsın RIF ile birlikte alloplastik materyaller kullanıldığında meydana geldiği bildirilmiş, ancak bu tekniğin daha fazla araştırma gerektirdiği rapor edilmiştir. 51 32 Beukes ve ark (2013) mandibuler ilerletme yaptıkları hastalarda cerrahi sırasında M. Pterigoideus medialis ve Stylomandibuler ligamentin uzaklaştırıldığı ve uzaklaştırılmadığı iki grubu karşılaştırmışlar ve uzun dönemde bu kas ve ligamentin uzaklaştırıldığı grupta stabiliteyi daha fazla bulmuşlardır. 54 Dicker ve ark'nın (2012) mandibuler ilerletme cerrahisi uyguladıkları vakalarda yaptıkları MR çalışmasında ise Masseter ve Medial Pterigoid kaslarının, mandibuler plan açısı 39°'den büyük olan hastalarda cerahi sonrası daha vertikal yönlü konumlandıklarını ve bu pozisyonel değişimin relapsta etkili olabileceğini rapor etmişlerdir.…”

“…4,9,11,[15][16][17][18]26,28,32,69,70 Başlangıç Açık Kapanış Miktarı Tedavi öncesi açık kapanış varlığının postoperatif relaps oluşumuyla ilişkisini araştıran yazarlar arasında farklı görüşler vardır. Denison ve ark.…”

Investigating the effect of age on skeletal stability after sagittal split ramus osteotomy for mandibular setback

“…to prevent relapse after SSRO surgery. The fixation method 4,5 , change of condyle position 5,6 , soft tissue or muscular activity [7][8][9][10] , gender 10,11 , amount of setback 11 , growth, and remodeling [10][11][12] were identified as the causes of relapse after operation. Although the age of patients could be easily assumed to influence the surgical prognosis, no study was mentioned with regard to the degree of relapse in setback SSRO surgery according to the age factor.…”

“…Although mandibular setback surgery is quite reliable and safe, longterm relapse had been a concern. The contributing factors of relapse after SSRO surgery include the fixation method 4,5 , change of condyle position 5,6 , soft tissue or muscular activity [7][8][9][10] , gender 10,11 , age [12][13][14] , amount of setback 11 , growth, and remodeling [10][11][12] . Although many…”