Long term effects of surgically assisted rapid maxillary expansion without performing osteotomy of the pterygoid plates

Journal of Cranio-Maxillo-Facial Surgery (2010) 38, 175e178 Ó 2009 European Association for Cranio-Maxillo-Facial Surgery doi:10.1016/j.jcms.2009.07.003, available online at http://www.sciencedirect.com

Long term effects of surgically assisted rapid maxillary expansion without performing osteotomy of the pterygoid plates Robin SEEBERGER, MD, DDS1, Wolfgang KATER, MD, DDS2, Rolf DAVIDS, MD2, Oliver C. THIELE, MD1 1

Department of Oral and Maxillofacial Surgery, University Hospital Heidelberg, Germany; 2 Department of Oral and Maxillofacial Surgery, Bad Homburg (Teaching Hospital of Frankfurt University Medical Center), Germany

Purpose: Surgically assisted rapid maxillary expansions (SARME) are commonly used to widen the maxilla. This study evaluates long term stability of surgically assisted rapid palatal expansion without performing osteotomy of the pterygoid plates and its effects on nasal airway volume. Materials and methods: 13 patients (mean age 31, 23 ^ 6, 11) with a maxillary transverse deficit of at least 5 mm were examined 1 month before and on average 63 months after a mean palatal distraction of 8.29 ^ 1.68 mm by acoustic rhinometry. Profiles of the nasal airway volumes were collected. A cast model analysis was performed. The data were evaluated using Wilcoxon signed rank test. Results: A V-shaped movement of the segments was observed. The gain for total nasal volume was 23.25%. Findings indicate a significant enhancement of nasal volume in all patients (P\ 0.01) as result of the maxillary expansion. No relapse occurred in the study group. Conclusion: SARME provides a long term stable orthodontic bite correction and permanently enhances the nasal airways. A transverse shift of the segments can be achieved over the whole bony palate even when no osteotomy of the pterygo-maxillary suture is performed. Ó 2009 European Association for Cranio-Maxillo-Facial Surgery

SUMMARY.

Keywords: distraction osteogenesis, osteotomy, rapid palatal expansion, acoustic rhinometry, cranio-maxillofacial

et al., 1997; Shemen and Hamburger, 1997). This study describes the surgical outcome 5 years after the operation in relation to the surgical approach described later. (Fig. 1).

INTRODUCTION Surgically assisted rapid maxillary expansion (SARME) as recommended by Bell and Epker (1976) is a wellestablished method for corrective transverse maxillary deficits in adults (Silverstein and Quinn, 1997). Crossbite and crowded teeth are a typical characteristic of maxillary compression syndromes. The mid palatal suture closes from posterior to anterior with a large variation in closing time from the age 16 to 35 years (Persson, 1973; Melson, 1975; Timms, 1986). Haas reported in 1970 that rapid maxillary expansion without surgical assistance is impossible after the age of 18. Due to the pillars of the upper facial skeleton, namely the apertura piriformis, crista zygomaticoalveolaris and sutura pterygopalatin (Han et al., 2009; Koudstaal et al., 2009). They create the resistance responsible for a maxillary collapse after widening (Haas, 1970; Bell and Epker, 1976; Neubert et al., 1989; Pinto et al., 2001; Wriedt et al., 2001). Current finite element studies showed that the crista zygomaticoalveolaris and sutura pterygopalatina create the main resistance for the expansion (Jafari et al., 2003; Holberg, 2005). There is no common consent over the surgical approach due to risk benefit considerations (Zo¨ller and Ullrich, 1991; Crosby et al., 1992). With acoustic rhinometry it is possible to examine the cross-sectional profile of the nasal airways. In combination with cast model analysis it was possible to describe the movement of the maxilla (Hilberg et al., 1989; Cory

MATERIALS AND METHODS This study was designed as a retrospective clinical monocentre study. Agreement was given by informed consent. 13 patients suffering from cross bite due to maxillary compression were included to the study. The SARME was part of a combined orthodontic treatment. No other surgical actions were needed. 8 female and 5 male patients with a mean age of 31.23 ^ 6.11 underwent a SARME. The acoustic rhinometry measurement was performed 1 month before and on average 63 months after the operation. The patients were given topical decongestion (xylometazoline 0,1%, 1 ml) 10 min before the examinations. An additional cast model analysis to include the dental expansion between the first molars (Pont’s points) was performed. Patients had no complex malformation syndromes like clefts or premature craniosynostosis and had no operation of the nasal complex before. We performed the operation as described by Bell and Epker (1976). Lateral osteotomy of the maxilla without the separation of the pterygoid plates was followed by osteotomy of the anterior portion of the lateral nasal wall. The palatal suture was then separated by malleting a thin Lambotts osteotome between the roots of the 175

176 Journal of Cranio-Maxillo-Facial Surgery

Fig. 4 e Finding at the end of orthodontic treatment.

Fig. 1 e Skull model schema illustrating the main structural pillars for the maxillary complex.

Fig. 2 e Example of initial finding of maxillary width compression.

The device was activated by 1 mm during surgery. The patients then started distraction 1 week after the operation by 2 turns a day (0.5 mm/d). The acoustic rhinometry measurement was performed with a Rhinoklack RK 1000 (IfM Leiche, Wettenberg-Launsbach, Germany). Acoustic rhinometry has been developed using the principles of impedance differences inside hollow spaces, when an acoustic pulse is applied (Hilberg et al., 1989). A 55 db acoustic pulse is given and the reflected acoustic pulse is then recorded within 10 ms. A cross-sectional and volumetric profile is now traceable by measuring the amplitude and velocity differences of output and reflected acoustic pulse (Cory et al., 1997). The total volume for each patient was divided into areas, the anterior, medium posterior segment of the nasal cavity and the nasal isthmus. The ranges were set in a distance from the nasal isthmus for the anterior segment 0e2.3 cm, the medium segment 2.3e4.6 cm and for the posterior segment 4.6e7 cm as described elsewhere (Kunkel et al., 1999; Wriedt et al., 2001). For pre and post therapeutic evaluation, a Wilcoxon signed rank was performed for all volumetric data with the level of significance set at P \ 0.01. RESULTS

Fig. 3 e Finding after distraction with tooth born Hyrax-jackscrew distractor in situ.

central incisors without any palatal incision. Distraction was then performed by a tooth born Hyrax-jackscrew fixed on to the first molars and the first premolars. (Figs. 2e4).

All patients showed a significant enlargement of the nasal volume as result of the palatal transverse distraction. The increase in volume was highly significant in the Wilcoxon signed rank test (P \0.01) for all the measured nasal segments. 5 years after the surgical approach the total nasal volume is increased in mean 23.25% Table 1 and Fig. 5). The volumes of the different segments indicate a V-shaped movement of the segments. The gain was greater in the anterior than in the medium and posterior segments. Enhanced nasal respiration was reported by all patients as a result of the widening. The nasal isthmus increased by a mean of 30.36%. No relapse of the maxillary expansion was observed. The cast model analysis showed a mean distraction width of 8.29 ^ 1.68 mm measured on Pont’s points of the first upper molar. Stable orthognathic occlusions were observed 63 months after treatment. All patients reported substantial improvement of nasal respiration (Table 2).

Effects of surgically assisted rapid maxillary expansion without performing osteotomy of the pterygoid plates 177

Fig. 5 e Irregular distributions of the volume gain in the different segments. Table 1 e Changes in the different segments pre- and postoperatively in cm3 (percentages) Variable

Mean

SD

Percent

Segment

Volume difference total Volume difference anterior Volume difference mid point Volume difference posterior Volume difference isthmus

5.95 1.00 1.95

1.17 0.24 0.44

23.25 25.31 22.11

0e7 cm 0e2.3 cm 2.3e4.6 cm

3.06 0.17

0.78 0.04

23.87 30.36

4.6e7 cm

Table 2 e The pre- and postoperative results in cm3 Variable

Pre (mean ^ SD)

Post (mean ^ SD)

Volume difference total Volume difference anterior Volume difference mid point Volume difference posterior Volume difference isthmus

25.55 ^ 0.96 3.95 ^ 0.29 8.82 ^ 0.43

31.49 ^ 0.94 4.95 ^ 0.44 10.77 ^ 0.64

12.82 ^ 0.92 0.56 ^ 0.05

15.88 ^ 0.38 0.73 ^ 0.03

DISCUSSION SARME clearly has an influence on the nasal airflow conditions as described elsewhere (Haas, 1970; Lines, 1975; Neubert et al., 1989; Mommaerts, 1999). Examining flow conditions, nasal volumes and cross-sectional profiles with acoustic rhinometry is a well-established, non-invasive method (D’Urzo et al., 1987; Hilberg et al., 1989; Kunkel and Hochban, 1994). It is well suited for follow-up controls (Hilberg et al., 1989; Kunkel and Hochban, 1994; Shemen and Hamburger, 1997). Han et al. (2009) concluded in their finite element study, that a pterygo-maxillary separation is an effective procedure for increasing the expansion of the maxilla with lower side effects for the anchor teeth. Our results show that a transverse shift of the segments can be achieved over the whole bony palate even though no osteotomy of the pterygo-maxillary suture was performed. In our study, widening of 22.11% and 23.87% for the

medium and posterior segment indicate a transverse shift in these segments is taking place. In this region, the tooth born distractor is utilized. The mean distraction width of 8.29 ^ 1.68 mm combined with orthognathic occlusion after the treatment emphasizes the results. Tooth tilting of the anchor teeth is a likely side effect of tooth born distractors. The wide range of distraction is only achievable if there is bony movement at the palatal suture. Our results indicate a V-shaped transverse movement of the segments. The result is underlined by the gain of 30.36% for the nasal isthmus and of 25.31% for the anterior Segment. The results of Kunkel and Hochban (1994) describing the maximum effects of mucosal decongestion found only a slight movement in the medium and posterior segments. Not separating the pterygoid plates as a resistance to the maxillary expansion (Jafari et al., 2003; Holberg et al., 2005) did not result in any relapse. Studies from Zo¨ller (1991) emphasize our results. Marchetti et al. (2009) reported a relapse of 28% in the intercanine and 36% in the intermolar distance after SARME even though they performed separation of the pterygoid plates. Analysing a cast models briefly post expansion, and 2 years later, with orthodontic treatment in between, the effects of the orthodontic treatment like teeth shift and tilt were not considered as explaining the results. Patients in our study experienced an increase in nasal airflow was also shown by Siddik et al. (2007). Our study showed a persistent increase in the total nasal volume of 23.25% combined with stable orthognathic occlusion five years after the surgical approach. Risk benefit considerations indicate that omitting separation of the pterygoid plates is possible (Koudstaal et al., 2005). CONCLUSION Long term stable bite corrections are achievable by surgically assisted rapid maxillary expansion even without separating the pterygoid plates. The results show a slight anterior-posterior V-shaped transverse shift of the segments. No maxillary relapse or malocclusion occurred.

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The total nasal volume increased by 23.25% and patients experienced a better nasal airflow as well as faster anastasis after the operation. Due to anatomical circumstances in the pterygo-maxillary fossa, our surgical approach provides a better risk benefit consideration.

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Robin SEEBERGER, MD, DDS Department of Oral and Maxillofacial Surgery University Hospital Heidelberg INF 400 69120 Heidelberg Germany Tel.: +49 6221 56 39716 Fax: +49 6221 56 4222 E-mail: [email protected] Paper received 13 March 2009 Accepted 3 July 2009