An interdisciplinary, medical, and dental approach to diagnosis and management would appear to be conducive to good patient care. It is generally recommended that initial medical assessment and diagnosis precede the prescription and initiation of oral appliance therapy (20). Once the medical decision to proceed with oral appliance therapy has been made, it is recommended that the dental component be carried out by appropriately qualified and experienced dental practitioners (20). During the initial dental consultation the oral health status is assessed for suitability and informed consent is obtained. A lateral cephalometric X-ray may be advisable to evaluate airway continuity and dimensions as well as for baseline documentation of the position and angulation of the teeth. A regular alginate impression with buccal and palatal soft tissue features is required. The precision of the impression depends on the design of the splint. A construction bite in an initial 75% protrusive mandibular position using regular pink wax is advised, as this amount of initial activation will represent a clinically reliable start point for the acclimatization phase (12). Existence of crowns and bridges, periodontally compromised teeth, as well as inadequate under-cuts need to be identified; these areas may need reduced retention, reduced in and out shear pressure, and may require modification of the regular appliance design. Extra clasps may be needed to increase retention in some cases. Following the insertion of the splint, patients may encounter problems fitting the splint and irritations to soft or hard tissues. These need to be corrected as soon as possible. It is common for patients to have uncomfortable sleep during the first few nights, but they usually reach an appropriate length of sleep after about a week. At the completion of titration, the patient should be re-evaluated from a medical perspective to ascertain the clinical response and to make decisions regarding the appropriateness of long-term use.
This is area requiring considerable research. Considering that there is wide variability in the reported efficacy across different studies, there is a strong suggestion that oral appliance design, in addition to dental expertise and titration procedures, has an important influence on treatment outcome.
The appropriate design of the appliance needs to take into consideration the occlusal and dental health, hard and soft tissues, the number of anchorage teeth, and the need for sagittal adjustment and/or reactivation, and this will vary on a case-by-case basis. Duobloc designs are generally preferable because of greater comfort and the ability to titrate, allowing attainment of the most comfortable and efficient position of the mandible and greater degree of lower jaw movements. MAS that permit lateral jaw movement or opening and closing whilst maintaining advancement may confer advantages in terms of reduction of the risk of complications and better patient acceptance. However, monobloc devices, whilst more rigid and bulky, are sometimes used to resolve issues related to anchorage needs, dental conditions, and the occlusal relationship.
Another important consideration is the vertical dimension of the oral appliance. Minimum vertical opening depends on the amount of overbite. Initial opening may be required before advancement of the mandible is possible, particular in cases with deep overbite (Fig. 6). However, if overbite is absent there may be no necessity to increase the vertical dimension. There are conflicting data on the effect of the degree of bite opening induced by oral appliances on treatment outcome, although most patients appear to prefer minimal interocclusal opening (21). In mouth breathing patients, splint design must have an anterior opening to permit comfortable breathing. In the case of edentulous patients wearing partial dentures, splint design should adapt to dental structures without dentures. In cases of insufficient teeth and concerns about retention there may be role for TRD.
FIGURE 6 Schematic diagram showing the influence of the depth of bite on the distance (d) of vertical opening required in order to permit advancement of the mandible. The deeper the bite, that is, the greater the overlap between upper and lower incisors in occlusion (as per this example), the greater the amount of vertical opening required.
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