CATEGORY AUSTRALASIAN DENTIST 51 LINICAL Also called MICROIMPLANT-assisted R.M.E technique (MARPE). Miniscrews are employed onto the maxillary expanders that recruits palatal and nasal cortices. This provides anchorage that facilitates opening of mid-palatal suture and helps to overcome resistance from circum- maxillary sutures. The advantageof correcting a transverse skeletal discrepancy is, 1. To prevent periodontal problems; 2. To achieve greater dental and skeletal stability 3. To improve dentofacial aesthetics by eliminating or improving lateral negative space. In severe maxillary transverse constriction or after growth has ceased, orthodontic treatment alone is not sufficient for successful expansion. These cases require a combination of surgery and orthodontic treatment, i.e. Surgically Assisted Rapid Maxillary Expansion (SARME). SARME Surgically assisted palatal expansion (SARPE) that cuts the bone for reducing the resistance without completely releasing the maxillary segments succeeded by jackscrew rapid expansion is another possible treatment approach in adults with narrow maxilla. Before surgery, fixed appliances can be used to move apart the roots of the central incisors to prevent the damage of roots by a midline maxillary surgical cut. Expansion is typically carried out at a rate of 0.5 mm a day. Due to the inelasticity of the palatal mucoperiosteum there will be more chances of relapse after surgical correction, so overcorrection is required to compensate the relapse. Technique for SARME – Hyrax expander is cemented onto the maxillary first molars and premolars before the surgical treatment, which includes bilateral osteotomies performed from the piriform rims to the pterygomaxillary junction. A screw expansion of approximately 2 mm is performed directly after surgery, and the screw is then activated once or twice a day until the desired expansion has been achieved. With a jackscrew attached to skeletal anchors, rapid disruption of the suture would be a disadvantage, so slow (<2 mm per week) rather than rapid expansion is indicated. u To widen the collapsed maxillary arch in cleft palate. u For pre-surgical arch expansion even in planned orthognathic surgery to prevent increased risks and inaccuracies with segmented total maxillary osteotomies. u It is also done when expansion required exceeds that which can be performed by segmental expansion (i.e. greater than 8 mm). u To expand the arch for creating space without premolar extractions, if the space required could be gained reasonably due to maxillary expansion and if other factors, like maxillary incisor protrusion on the underlying bone, have been considered. Complications u Palatal tissue irritation is a frequent complication of SARPE. u Irritation occurs due to impingement of appliance or rapid rate of expansion. u Other complications include haemorrhage, gingival recession, root resorption, sinus infection, extrusion of teeth, relapse and unilateral expansion. 7. EFFECTS OF THE RME On the Maxillary Teeth and Alveolar Bone u The posterior teeth are used as handles to transmit forces to the maxilla which tends to tip buccally due to the compression of the periodontal ligament on the pressure side. u Bending of the adjacent alveolar process along with limited tipping and/ or extrusive orthodontic movement of the teeth. u Distinct appearance of a midline diastema, which appears within days of initiating RME therapy. The diastema is generally half the distance of the distance by which the screw is activated. The diastema is reported to close simultaneously within 6 months due to the trans-septal fiber traction. Maxillary Skeletal Effects u The palatine processes separate in a triangular or wedge- shaped manner when viewed occlusally. A similar triangular opening is also seen in the supero-inferior direction, maximum towards the oral cavity and progressively less towards the nasal aspect. u Maxilla moves laterally due to expansion and also rotates with the fulcrum at frontonasal suture. u Increase in nasal airway, reduction in airway resistance. u Downward and backward rotation of mandible. u Increase in mandibular angle. Temporary anchorage device TAD supported RPE Paramedian area 3mm lateral to the suture in 1st premolar region is considered the most appropriate site for placement of miniscrews anterior screws are placed in rugae. Skeletal anchorage should permit orthopaedic change without the adverse dental changes by applying force directly to the maxillary bone. Indications The skeletal anchorage could be reserved for: u moderate to severe skeletal discrepancies, u skeletally mature individuals, u periodontally involved cases, u patients with missing teeth. Skeletal-anchored RPE produced less molar tipping than the toothtissue- borne RPE. Comparing the boneanchored to the bonded tooth-tissue- borne expander treatment, expansion efficacy demonstrated in both has significant skeletal changes. However, the bone-anchored devices achieved (25%) significantly more skeletal change without dental compensation than did the bonded tooth-tissue-borne device. Indications SARPE is indicated for the treatment of the adults with narrow palatal arch for the following: u To expand the arch for correcting posterior crossbite when no other surgical jawmovements are considered.
RkJQdWJsaXNoZXIy MTc3NDk3Mw==