Surgically assisted rapid maxillary expansion: feasibility of not releasing the nasal septum

Abstract

Surgically assisted rapid maxillary expansion (SARME) is commonly used to correct maxillary transverse deficiency. The aim of this study was to analyse the need for intraoperative liberation of the nasal septum during the procedure. SARME was performed in 25 patients by combining a lateral osteotomy with an inter-radicular maxillary osteotomy. The deviation of the nasal septum after SARME was evaluated by comparing measurements between radiologically defined landmarks on pre- and postoperative computed tomographic images. Two defined angles (angle I, between crista galli-symphysis mandibulae and crista galli-septum nasi; angle II, between maxillary plane and septum nasi) were measured based on four representative planes and septal movement was analysed. The mean changes in angles I (0.03° ± 0.78°) and II (0.25° ± 1.04°) did not differ significantly from zero ( p = 0.87 and p = 0.24, respectively). Observed variations and displacements were considered to be acceptable because they were insignificant in every respect. Intranasal airway function was also examined pre- and postoperatively to evaluate any loss of ventilation. The described surgical technique is a successful method of maxillary segment distraction. The authors found no compelling reason to release the nasal septum in the context of SARME.

Surgically assisted rapid maxillary expansion (SARME) is a form of surgical distraction first described theoretically by Codivilla. It was introduced in 1938 as a combined surgical and orthodontic treatment. Today, SARME is considered to be a valid treatment for severe transversal maxillary discrepancy and dental crowding. Patients undergoing this procedure must be skeletally mature, present a certain transverse maxillary hypoplasia, and/or have a failed orthodontic maxillary expansion. Thus, SARME is commonly used to correct skeletal maxillary transversal deficiency in cases of intermaxillary suture ossification and is a widely accepted surgical technique in patients older than 15 years with a transverse maxillary deficiency > 5 mm. Although SARME is a well-established treatment, no significant consensus on surgical technique has been reached, apart from the use of minimally invasive and more invasive osteotomies. A wide variety of methods (e.g. osteotomy, structure release) and materials (e.g. bone- or tooth–borne distractors) are used to correct transverse maxillary deficiencies. A minimal surgical approach is required to produce consistent and stable maxillary expansion in adults. The intermaxillary suture and pterygomaxillary buttress offer the most resistance to maxillary expansion. Palatinal and lateral osteotomies are common and accepted SARME techniques because they produce stable maxillary expansion.

Treatment of the nasal septum also varies; it is frequently released from its palatal base to avert septal deviation, septum side-shifting, and nasal airway changes.

The aim of this study was to analyse the need for nasal septum liberation by surgical sectioning in the course of a SARME.

Materials and methods

This retrospective study included 25 patients treated in the Department of Oral and Maxillofacial Surgery (Graz, Austria). Inclusion criteria were: cross bite with transverse loss of distance of >5 mm, closed intermaxillary suture, age >16 years, and availability of complete records, including pre- and postoperative computed tomography (CT) scans. Syndromic patients and those with cleft lip and palate or cleft palate, severe asymmetry, and/or limited periodontal health were excluded.

Surgical treatment

The same surgical treatment was performed in all patients by experienced senior surgeons (S.G., K.H., S.M., F. M., R.K.). In all 25 cases, SARME was performed under general anaesthesia by combining a lateral osteotomy through the zygomatic buttress from the piriform rim to the maxillopterygoid junction with an inter-radicular maxillary osteotomy (sagittally between the roots of the central incisors).

Distraction, activation period, and retention

A Haas-type expander ( Fig. 1 ) was used to distract the hypoplastic maxillary segments. The bands of the Haas device were mounted on the first premolars and molars in all patients.

Fig. 1
Haas-type expander used to distract maxillary segments.

Two days postoperatively, the patients began to activate the distractor twice per day (one turn in the morning, one in the evening; 1 mm/day) until achieving ≥3 mm over-expansion. The Haas device was kept in place for at least 12 weeks for retention.

Radiological evaluation

The displacement or deviation of the nasal septum after SARME was evaluated by comparing defined landmarks on coronal CT scans (1.5 mm slices; Siemens, Erlangen, Germany). In all patients, CT images were acquired preoperatively to exclude the presence of inflammatory processes and 6–8 weeks postoperatively for three-dimensional planning of orthognathic or oral surgery.

Measurements were taken between anatomical landmarks on CT images based on four representative maxillary planes that were drawn to define two angles ( Fig. 2 ): angle I, between crista galli-symphysis mandibulae and crista galli-septum nasi; and angle II, between the maxillary plane and septum nasi. Measurements of both angles were compared to assess septal deviation ( Fig. 2 ). All pre- and postoperative measurements were taken twice (variants 1 and 2) by two observers (a senior surgeon (S) and a specialised radiologist (R); Table 1 ).

Fig. 2
Measurement of angles I and II using anatomic landmarks on CT images. Preoperative (left) and postoperative (right) examples drawn from 25 cases. Upper: angle I, between crista galli-symphysis mandibulae and crista galli-septum nasi. Lower: angle II, between the maxillary plane and septum nasi.

Table 1
Statistical calculations of measured angles I and II.
Angle Variant 1 Variant 2 Mean diff a p -Value SD a SE a
I Preop S Preop S 2 0.004 0.79 0.07 0.01
Preop R Preop S 2 −0.028 0.17 0.10 0.02
Postop S Postop S 2 0.044 0.17 0.16 0.03
Postop R Postop R 2 −0.012 0.48 0.08 0.02
Postop S (mean) Preop S (mean) 0.264 0.22 1.04 0.21
Postop R (mean) Preop R (mean) 0.24 0.26 1.04 0.21
Preop S (mean) Preop R (mean) −0.008 0.44 0.05 0.01
Postop S (mean) Postop R (mean) 0.016 0.30 0.08 0.02
Postop (all mean) Preop (all mean) 0.252 0.24 1.04 0.21
II Preop S Preop S 2 0 1.00 0.29 0.06
Preop R Preop R 2 0 1.00 0.41 0.08
Postop S Postop S 2 −0.06 0.19 0.22 0.04
Postop R Postop R 2 0 1.00 0.00 0.00
Postop S (mean) Preop S (mean) 0.05 0.76 0.81 0.16
Postop R (mean) Preop R (mean) 0 1.00 0.84 0.17
Preop S (mean) Preop R (mean) 0.08 0.29 0.37 0.07
Postop S (mean) Postop R (mean) 0.13 0.07 0.35 0.07
Postop (all mean) Preop (all mean) 0.025 0.87 0.78 0.16
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Jan 24, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Surgically assisted rapid maxillary expansion: feasibility of not releasing the nasal septum
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