Medical knowledge | Dentistry » Simon-Nicholas - Dental appliances for snoring and obstructive sleep apnoea, Construction aspects for general dental practitioners

L N E T IPCRS O S T H O D O N T I C S R E M O V A B L E RP ER M O SOTVH A OB DO Dental Appliances for Snoring and Obstructive Sleep Apnoea: Construction Aspects for General Dental Practitioners SIMON G.S ELLIS, NICHOLAS W CRAIK, ROBERT F DEANS AND CHRIS D HANNING Abstract: The medical and dental aspects of management for patients diagnosed with snoring and obstructive sleep apnoea are well documented. However, guidance for treatment by the general dental practitioner is lacking. This article reviews aspects of appliance provision and presents the use of a silicone material in an attempt to improve the longevity of a recognized prosthesis. Dent Update 2003; 30: 16–26 Clinical Relevance: This paper informs the general dental practitioner of the concepts, rationale and financial implications of the types of dental appliances available for sleep-related breathing disorders and presents a technique to construct a one-piece flasked silicone prosthesis. T he management and treatment of

patients who suffer from snoring and obstructive sleep apnoea (OSA) have long since been addressed by medical1,2 and specialist dental publications3–5 and were recently highlighted by a number of mainstream dental articles.6–10 These articles inform the general dental practitioner (GDP) of the medical implications of the problem and the medical and dental treatment options available, but provide little technical information on constructing these appliances in the general practice setting. Traditionally, such appliances have been Simon G.S Ellis, BDS, MSc, FDS RCS(Edin), Specialist Registrar, Nicholas W. Craik,Adv Ortho & Pros, RDT, LOTA, Senior Chief Dental Technician, and Robert F. Deans, BDS, FDS RCS(Eng.), FDS RCPS(Glasg), FFD RCSI (Ire), DRD RCS(Edin.), Consultant, Department of Restorative Dentistry, Glenfield Hospital, University Hospitals of Leicester NHS Trust, and Chris D. Hanning, MD, FRCA, Consultant in Sleep Disorders Medicine, Leicester General Hospital. 16

provided in a hospital setting. The department of Orthodontics and Restorative Dentistry at Glenfield Hospital, part of the University Hospitals of Leicester NHS Trust, has eight years experience in producing appliances and currently receives in the region of 200 referrals a year from a sleep disorders clinic. During this time, various designs and materials have been used. However, as the awareness of treatment with dental prostheses increases (for example with newspaper reports11 and dental advertising12), GDPs may wish to offer this treatment to the claimed one in four patients who snore. This paper is written to give guidance to those dentists providing appliances in general practice. The article reviews the concepts, rationale and technical aspects of appliance design and discusses clinical and financial issues for the GDP. We also present the clinical and laboratory stages in constructing a one-piece silicone appliance that have been established within the department. No attempt

is made to revisit the medical aspects or the alternative treatment options for sleeping disorders. RATIONALE AND CONCEPTS OF APPLIANCE DESIGN Snoring is a sign of partial upper airway obstruction during sleep. Snoring and OSA are caused by abnormal airway (base of tongue and soft palate) anatomy and altered respiratory control mechanisms. Dental appliances may prevent snoring and OSA by modifying the position of the upper airway structures so as to enlarge and/or reduce collapsibility of the airway. Both the superior airway space (between the soft palate and posterior nasopharynx) and the posterior airway space (between the base of the tongue and posterior oropharynx) may be increased.13 Threedimensional reconstructions of computed Figure 1. Change of mandibular position Dental Update – January/February 2003 REMOVABLE PROSTHODONTICS Appliance name Description Type Occlusal coverage Adjustable Soft Palate Lifter Lifts the soft palate and prevents vibration during sleep

One-piece Full Equaliser24 Repositions the mandible anteriorly, equalizes intra- and extra-oral air pressure (via tubes) and elevates soft palate One-piece Full Herbst2,24 Repositions the mandible anteriorly, in open and closed position, with adjustable struts. Two-piece Full Jasper Jumper24 Repositions the mandible anteriorly Two-piece Full Mandibular Repositioner2,24 Repositions the mandible anteriorly (3–7 mm) One-piece Full Nocturnal Airway Patency Appliance24 Repositions the mandible anteriorly and inferiorly One-piece Full Sleep and Nocturnal Obstructive Repositions the mandible anteriorly (6–9 mm) and inferiorly (17 mm) Apnoea Reducer (SNOAR)24 One-piece Excludes anterior maxilla Snore Guard2,24 Repositions the mandible anteriorly (3 mm behind maximal protrusion) and inferiorly (7 mm) One-piece Excludes molars Snoring Treatment Appliance24 Repositions the mandible anteriorly One-piece Excludes molars Tepper Oral Proprioceptive Stimulator24

Modifies tongue position One-piece Not applicable Tongue Locking Device24 Preformed elastic appliance with a cavity that holds the tongue forward by self-created vacuum One-piece Full Tongue Positioner and Exerciser24 Helps train the tongue to be in a more favourable position One-piece Full Tongue Retaining Device2,24 Holds the tongue anteriorly during sleep by negative pressure in a bulb One-piece Full Klearway2 Keeps teeth together, holding mandible and tongue forward Two-piece Full Advances mandible, vertical opening of 5 mm Two-piece Full Lower fin prevents tongue and mandible dropping back Two-piece Full 24 PM Positioner Therasnore2 2 Table 1. A summary of dental appliances described for the treatment of snoring and obstructive sleep apnoea (adapted from Lowe2,24) tomography and magnetic resonance imaging scans demonstrate significant increases in airway dimensions with the appliances.14,15 Successful treatment has, and continues to be, demonstrated

– from questionnaires of patients and their partners and scientifically from sleep study polysomnography.2,3,13,16,17 The effectiveness of appliance therapy, however, depends on the severity of the sleeping disorder, the airway anatomy18 and whether the patient can tolerate the appliance. It is generally advocated for mild OSA and simple snoring (i.e snoring in the absence of OSA) and moderate to severe OSA as an alternative to nasal continuous positive airway pressure (nCPAP) or craniofacial surgery.19 The use of intra-oral appliances is simple, non-invasive, reversible and costeffective and may be the basis of Dental Update – January/February 2003 definitive lifelong treatment. The technical aspects of construction have been evolving since the early 1980s,20,21 although prostheses were first considered in the early 1900s.22 Originally there were three concepts for a dental appliance to modify the airway, which could be used alone or in combination depending on where the airway

obstruction occurred: l Soft palate lifting – the prosthesis lifts and/or stabilizes the soft palate, preventing vibration during sleep.5 l Tongue retention – tongue-retaining devices (TRDs) incorporate an anterior hollow bulb, which generates a negative pressure vacuum when the tongue is inserted. The tongue is held forward, away from the posterior pharyngeal wall, opening up the airway. Owing to muscle anatomy, this appliance simultaneously modifies the position of the mandible.13 l Mandibular repositioning – these appliances (MRAs) hold the mandible in an anteroinferior position, which, as a consequence of muscle attachment, indirectly brings the tongue forward, opening up the posterior airway (Figure 1). The repositioning may also stretch and reduce the collapsibility of the soft palate via its connection to the base of the tongue and increase the superior airway space.13,17 A recent review of 129 papers suggested that more than 35 appliances are currently available,23

although Lowe estimates the number to be in excess of 55. 17 REMOVABLE PROSTHODONTICS Figure 2. Conventional vinyl MRA (nonadjustable) Figure 3. Green polyvinyl MRA (non-adjustable) He analysed the literature relating to 13 commercially available appliances24 but focuses on seven designs in his recent work (see Table 1), which is probably the most authoritative text available. The soft palate lifting design is not often used because of patient tolerance and the fact that tongue posture rather than soft palate position is considered to have a significant influence on the patency of the upper airway.25 An example of this type of appliance is clearly shown in the paper by Clark and Nakono.5 Whilst TRDs directly move the tongue to open the airway, patient tolerance is not satisfactory. When appliances are indicated the consensus appears to be a type of MRA, which Johal and Battagel consider most suitable for obstructions at the level of the tongue.7 However, there is considerable

variation with respect to the vertical and horizontal planes of mandibular repositioning and the material used for construction. Mandibular Repositioning Considerations Appliances for the treatment of snoring and OSA have been described with different degrees of horizontal and vertical repositioning. The most common 18 mandibular repositioning dimension quoted is 50–75% of maximal protrusion (approximately 5–7 mm) with minimal vertical opening.2,5,6,10 The rationale for minimal opening is that, as the mandible opens, it rotates in an inferior and posterior direction. Concurrent posterior movement of the tongue and soft palate with wider opening may narrow the pharyngeal airway.7 Other authors favour a 75% anterior position with a vertical dimension of 7 mm,2,17 whilst the SNOAR appliance in Table 1 has significant anteroinferior repositioning. This, in contrast, is stated to work by moving the mandible and tongue away from the posterior pharyngeal wall and soft palate.2 Bonham et

al. advocated a more pragmatic approach in describing the most comfortable protrusive position.3 An extensive review led by Ivanhoe found a variety of protrusive dimensions were associated with successful outcomes.23 This, along with Lowe’s text,24 suggests that most protrusive positions are effective. Material Considerations To date either poly-vinyl vacuum-formed thermoplastic materials (soft or stiff blanks depending on the Shore-hardness) or hard acrylic (predominantly heat cured) can be used. The choice of material often depends on appliance design and operator preference. To optimize retention for the vinyl appliances it is recommended that the flanges extend at least 3 mm past the gingival margin but, if softer vinyl is used, this depth should be increased. Occlusal coverage Figure 4. MRA at an increased vertical dimension. Figure 5. IST Appliance – an adjustable two-part Herbst-type appliance. sufferers has been described.26 If retention is a problem then a TRD may be

an alternative option.20 SOME DESIGNS OF MRAS Appliances can be considered as either one- or two-piece designs. One-piece designs are not adjustable whilst the twopiece appliances can be adjusted in the anteroposterior plane. They may also permit, as with the Herbst-type appliance, The designs in Table 1 have varying occlusal coverage but ideally complete occlusal coverage should be prescribed to prevent the potential of localized tooth over-eruption. Case reports of complications occurring when full coverage was not used are discussed below. Edentulous Patients Most appliances are made for dentate mouths but a technique for edentulous Figure 6. The Silensor – an adjustable two-part appliance. Dental Update – January/February 2003 REMOVABLE PROSTHODONTICS Figure 7. An orthodontic Twin-Block functional appliance. Figure 8. Twin-Block design with no coverage of occlusal surfaces anteriorly. limited lateral movements for parafunctional patients. One of the most accepted

designs is the one-piece non-adjustable soft vinyl vacuum-formed MRA (Figure 2). This involves fusing the thermoplastic material covering the maxillary and mandibular arches in the desired anteroinferior position. The occlusal position is established and recorded in vivo by a variety of methods including a wax-bite, silicone-bite or anterior jig with an interocclusal registration.6,9,17 An optional anterior breathing hole can be placed to reassure those patients who mouth breathe but is not essential. Figure 3 illustrates a variation of a one-piece nonadjustable MRA using stiffer green vinyl Figure 9. Modification of the Twin-Block to help prevent disengagement at night. 20 of Shore hardness 80; Figure 4 shows an appliance made at an increased vertical dimension of approximately 8 mm. In the two-part Herbst-based IST (IntraOral Snoring Therapy; Figure 5) and Silensor (Figure 6) appliances, the arches are connected by pivoting bars that can be altered in length to titrate the

protrusive mandibular position for effectiveness and comfort. The occlusal registration for these two-part appliances is not as important because mandibular repositioning can be titrated from the intercuspal position. Although designed for orthodontic treatment, the Twin-Block functional appliance can be used as a MRA because its (two-piece adjustable) design allows adjustment of the mandibular position by removing or adding acrylic (Figures 7 and 8). These adjustments will be difficult, however, if modifications have been included in an attempt to prevent nocturnal mandibular opening (Figure 9). It is crucial that full coverage of the maxillary and mandibular occlusal surfaces is provided to prevent over-eruption and the technician knows that the appliance is for sleep breathing disorders rather than orthodontics. The recently advertised Therasnore Zx has a different approach, in that the appliance engages only the maxillary dentition and relies on a lingual fin to induce protrusive

mandibular repositioning and/or prevent the tongue and mandible from dropping backward during sleep.2,27 It is two-part in design and adjustable via five slots of 1.5 mm increments (Figures 10–12). It is believed that if a patient opens their mouth at night the appliance will not function. To counteract this locking, elastics are advocated for the two-part Herbst-type appliances and adequate retention of the dental arches is needed for the one-piece prostheses. However, one must question this theory as a rule. For example, the Therasnore Zx engages only the maxillary dentition and relies on the mandible being closed for the lingual fin to effect mandibular repositioning. The anterior repositioning splint (ARPS) described for temporomandibular disorders is similar to the mandibular repositioners in Table 1.28 The ARPS either Figure 10. In vivo fitting of the Therasnore Zx appliance. Figure 11. The Zx is an adjustable two-part appliance. Figure 12. The increments of the Zx fits the

maxillary dentition and relies on the mandible being closed or vice versa, but again clinical studies demonstrate success:2 indeed, the ARPS design has been used successfully in our department (Figure 13). One patient did keep opening his mouth at night and disengaged the standard MRA despite attempts at maximizing retention. Another variation was attempted, at the patient’s request, to address this. In light of the SNOAR appliance described in Table 1, an appliance was made to a vertical opening of 16 mm and has been successfully, effectively and uneventfully worn for over 3 years (Figure 14). Dental Update – January/February 2003 REMOVABLE PROSTHODONTICS Identical success rates were found for the Silensor and MRAs with 3 mm or 8 mm interincisal opening (Figures 2, 4 and 6). DURABILITY AND LONGEVITY OF MRAS Figure 13. A one-piece heat-cured acrylic nonadjustable MRA (an ARPS) ARE MRAS ALWAYS SUCCESSFUL ? Lowe’s text comprehensively documents outcome success rates for

many different MRA designs.2,24 Rates vary between 50 and 90% and depend on factors such as diagnosis, severity of the disorder and (more critically) on the scoring value for success, as successful outcomes in one study would not be considered a success in another! In our recent audit using three different MRA designs, a success rate of 67% was scored by patients for whom the appliance was often first-line treatment.29 Stage The laboratory construction of the common one-piece Erkoflex MRA is relatively simple and economic but the longevity varies as the appliance may split where the blanks are ‘glued’ together (Figure 15). Appliances may also become loose with parafunctional forces, cleaning procedures (especially with hot water) and gradual deterioration of the thermoplastic material. The thermoplastic Silensor is also at risk of breakage at the hinge site, which protrudes and is a tempting point of application for removal. The hinge may also cause discomfort to the lips. Acrylic

prostheses do not suffer from splitting and can be cleaned with chemical agents and warm water. Further, they can be relined at the chairside with cold-cure acrylic if any looseness occurs. Flange tears, broken and displaced repositioning wires and fracture of the connector pins were durability problems highlighted recently by Tyler.30 He was concerned at the parafunctional forces the appliances had to withstand and advocated a regular recall programme to inspect for defects. Longevity of appliances is considered to be around 2 years but will vary between individuals.31 ODONTOSIL SILICONE MATERIAL AND THE GLENFIELD APPROACH Our original MRA approach was the glued Erkoflex 95 (Shore hardness 95) design. This method of construction requires an accurate record of a comfortable protrusive mandibular position, which is used to mount the working casts on an articulator. Erkoflex blanks are vacuum pressed over the opposing casts before a glue gun heats vinyl sticks to fill the space between

the maxillary and mandibular arches and produce a strong resilient seal. However, this ‘gluing’ process occasionally fails and the appliance splits apart along the glue joint. As with other Description Patient counselling Patient informed about what the appliance treatment involves and related to the medical diagnosis from the referring sleeping disorder specialist. Written consent for treatment obtained Price agreed and plans discussed on what to do if appliance does not work. Clinical records Maxillary and mandibular impressions recorded with the preferred material. The Glenfield registration protocol is the most comfortable protrusion mandibular position with a tooth contact. This contact serves to stabilize the relationship whilst the interocclusal registration material sets. Once patient has practised finding and maintaining the position the registration is made with injectable interocclusal silicone material. Preparation of master models Kaffir ‘D’ plaster vacuum

mixed for master casts. Casts trimmed to an appropriate size for articulator, which must be at least capable of hinge movements. Casts articulated to the recorded maxillo-mandibular relationship and marked so they can be removed and replaced accurately. Articulator opened 2–3 mm to allow space for the material and (if required) a breathing hole Wax-up Any undercuts not blocked. Double sheet of wax laid over upper and lower casts in horseshoe style, extending into the sulci Wax cut away over the central incisor teeth to accommodate a breathing hole (if required for mouth-breathers) and wax bases sealed. Articulator closed to the desired vertical dimension and wax added to seal the maxillary and mandibular units. Smooth finished wax surface produced for the finished appliance as cured silicone is difficult to trim and polish. Flasking To allow access to the labial section of the appliance when injecting the silicone a small amount of laboratory putty should fill the breathing hole.

Appliance flasked with the lower cast in one half and the upper cast in the other half of the flask Casts modified so they fit the flask without obstruction – the lingual plaster of the mandibular cast should be removed to aid this process. The rest of the flasking procedure carried out as per acrylic. Unifol insulating film is used to coat the plaster surfaces Odontosil (60 Shore) is gunned from the double cartridge through a mixing tip and applied separately to both halves of the flask without trapping air. Putty spacer positioned and the flask closed slowly to ensure a thin flash. Flask kept under pressure for 30 minutes Finishing Appliance de-flasked, flash cut off with scissors and finished with soft lining finishing wheels. The trimmed appliance can be sealed and given a shine with Odontosil lacquer. Fit Written instructions provided. Patients advised to acclimatize during evenings for 1–2 weeks before first wearing at night Patient’s sleeping disorder specialist

advised that the appliance has been produced. Comfort and fit of the appliance reviewed after a month Patient should undergo regular dental checkups at which appliance is periodically checked. Table 2. Clinical and laboratory stages for construction of a MRA at the Glenfield Hospital Dental Update – January/February 2003 21 REMOVABLE PROSTHODONTICS thermoplastic designs, the appliance may loosen. The ideal design is probably the more rigid acrylic two-piece adjustable Herbst-type appliance but this design was not financially viable for the department. Materials were sought to construct a one-piece MRA that would resist splitting. We experimented with heat-cured silicone (Monoplast-B) but found this unsuccessful because of difficulties in flasking and finishing; however, Odontosil 60 (Dreve-Dentamid, GMBH) was more promising. It is a soft silicone with a Shore hardness of 60 and comes as a double cartridge system, similar to the lowviscosity silicone systems for crown and

bridge impressions, with a mixing tip that enables flasking without introducing air bubbles. The clinical and laboratory stages are outlined in Table 2 and Figures 16–25. FINANCIAL ASPECTS In a recent personal communication, the Dental Practice Board stated that they consider MRAs to be ‘medical devices for a medical condition rather than a dental condition’ and as such ‘there is no provision in the NHS fee structure to make payments under the General Dental Service’.32 They did advocate that practitioners could approach their local health authority to negotiate a specific contract to treat patients. At present, and for the foreseeable future, patients will have to pay privately. Hospital-based treatment has the luxury of cost being secondary to patient care and as such clinicians may not, therefore, fully appreciate the financial implications of advocating treatment in general practice. To highlight this, various material charges and other aspects are set out in Table 3.

Commercial laboratories in Trent charge in the region of £79–85 for a Silensor, £60–72 for a Twin-Block, £35–50 for an ARPS and £142.50 for an IST appliance.33 In fact, all laboratory-made appliances take approximately the same amount of time to construct, apart from the Twin-Block, and the cost therefore will depend more on the materials used. A Herbst-type appliance is more expensive as a set of adjustable bite jumping hinges costs £32. The Therasnore Zx recently received attention in the national and dental press and its marketing campaign claims a clinical (fitting) time of 20 minutes.11,12,27 It has an in vivo construction approach similar to the heat-and-mould (‘boil-in-thebag’) type sportsguard and thus an advantage of no laboratory fees, although the material for each appliance costs £74– 85 plus VAT.34 There is no standard ‘private fee’ advocated for the Zx, although the recommended price is £225. Whilst any dental appliance has a finite lifespan,

maximizing longevity is a crucial factor as repairs will have financial implications. PATIENT PERCEPTIONS, COMPLICATIONS AND FOLLOW UP Patients may recall, when questioned, the Appliance Materials and bulk costs Material cost per appliance Laboratory time and quoted charges GDP charge Silicone snorestop 24 ml Odontosil 60 (8 x 48 ml £132); £9.50* 4 hours* No standard £8.00* 4 hours* No standard £12–65* 3–4 hours*; £79 and £85 No standard Odontosil lacquer (50 ml £23) Conventional polyvinyl appliance 2 Erkoflex 95 blanks (6 x 4 mm square blanks £20.40); 1 Erkoflex 95 glue stick (18 glue sticks £17.70) Silensor 1 set of hinges (10 pack £83.60); 2 Erkoflex 95 blanks (12 x 2.5 mm square blanks £2590) Anterior repositioning splint Acrylic and clasps Negligible 4 hours*; £36-£60 No standard Adjustable Herbst Bite jumping hinges (£32 per pair); £32* 3–5 hours*; £120–£125 (minimum) No standard Acrylic and clasps IST – – Set charge

£142–150 No standard Therasnore Zx £85 + VAT for 1–3; £74 + VAT for 8; Starter pack £289 inc VAT for 3 £74–£85 – RRP £225 Twin-Block Acrylic and clasps Negligible 4–6 hours*; £60–£72 No standard *Approximately Table 3. Details relating to construction of appliances 22 Dental Update – January/February 2003 REMOVABLE PROSTHODONTICS Figure 14. A non-adjustable vinyl MRA with significant opening of the vertical dimension. Figure 15. Splitting of ‘glued’ vinyl blanks MRA remounted for repair. Figure 17. The vertical dimension is increased to provide about 3 mm inter-incisal space. Figure 20. Silicone insert for preserving breathing hole. Figure 23. Injection of Odontosil with mixing tip. 24 Figure 18. Profile view showing the desired repositioning. Figure 21. Flasking procedure Figure 16. Casts are mounted using the bite registration. Figure 19. Completed wax-up of MRA Figure 22. Wax boiled out Silicone remains to provide space for

breathing hole. Figure 25. The completed Odontosil MRA Figure 24. Deflasking the MRA Dental Update – January/February 2003 REMOVABLE PROSTHODONTICS Information about the Snorestop Appliance This handout attempts to inform you about your proposed appliance – the Snorestop. l Your motivation and dedication to the Snorestop is essential for any chance of success. l The Snorestop WILL feel very strange initially but you will adapt to it (it is similar to ‘gum shields’ worn for contact sports). l Do not wear it at night UNTIL you can tolerate it – wear it a few hours a day/evening to acclimatize (watching TV, reading, etc.) l Individuals often notice different tastes, increased saliva, nausea/retching sensation, soreness of gums, facial discomfort – this is generally temporary. l The material may stain with certain foods – do not worry. Clean gently with toothbrush and toothpaste/soap (don’t use hot water) or, if there are no metal components, soak in a dilute Milton

solution during the day. l Do not make any judgements on its success for at least a month of proper use. l Phone ####–####–#### if you have any problems. IF YOU CANNOT WEAR THE SNORESTOP PLEASE LET US KNOW AT THE REVIEW APPOINTMENT AND WE WILL DISCUSS FURTHER OPTIONS Figure 26. Patient information leaflet following problems associated with wearing an MRA:2,13,29,35–37 l episodes of dry mouth; l increased salivation; l facial and/or temporomandibular discomfort; l momentary change in occlusion on waking; l nausea; l choking; l unpleasant taste; l worsened breathing problems. However, these symptoms are usually transient and part of the adaptation process – and are insignificant compared with the potential complications of alternative treatments of surgery to the maxilla, mandible, tongue or soft palate. In a recent prospective audit within our department, 74% adapted within 2 weeks and only 6 of the 45 patients could not tolerate the MRA.29 Compliance appears to be related to

a patient’s ability of adaptation and tolerance in a similar manner to dentures. In addition, perseverance, which could be dependent on the morbidity of the sleeping disorder and experience of unsuccessful treatments such as nCPAP, could prove to be an important factor. Side-effects per se of appliance treatment are not conclusive.5,7,13,35,36 Bondemark reported small but statistically significant radiographic changes in mandibular position and incisal overjet (OJ) and overbite (OB) from a 2-year Dental Update – January/February 2003 study:37 the mean, standard deviation and ranges were 0.4(±05) and 00–20 mm for OJ and 0.1(±03) and 00–10 mm for OB but no control group was used. Marklund et al. also reported changes in OJ and OB in a study over 1.9–42 years:38 the changes in the test group were very small (OJ: 0.4(±08) mm, OB: 04(±07) mm) and also occurred in the reference group (OJ: 0.2(±04) mm, OB: 04(±05) mm) Both of these studies used full occlusal coverage MRAs and

measurements were taken to the nearest 0.5 mm In a retrospective telephone and postal survey Clark et al. found that up to 44% of patients wearing full-coverage MRAs reported occlusal changes that were not transient. However, as there was no clinical follow-up examination, the significance of this finding was not discussed, although they did propose occlusal changes to be more prevalent than previously thought, despite the evidence from the study being inadequate to make such a statement.35 Clinically significant findings have been reported for two patients in whom acrylic appliances were used that did not cover the anterior maxillary teeth39 (it was the belief that this space was required for breathing). Amongst other findings a decrease in excess of 2 mm in OJ and OB in just over 2 years was reported but no temporomandibular joint (TMJ) or muscle problems were encountered. The latter outcome data cannot, however, be applied to appliances with complete occlusal coverage. Long-term

data is required to assess potential detrimental effects on the TMJ, associated musculature and occlusion so that patients can be accurately informed about potential complications – especially patients who may have to wear a MRA for life. However, the authors of a recent review were keen to reinforce the view that minor changes should be balanced against the efficacy of the appliances.36 Caution has been advised when treating patients with previous temporomandibular disorders and severe bruxism.2,5 As symptoms may worsen in some patients, it is important for the diagnosis to be ascertained before treatment is commenced and the patient followed up by a medical specialist when appropriate. Potential direct or indirect detrimental effects on oral health of the appliance should be monitored by regular dental recalls; at the same time the longevity can be assessed and replacements made when necessary. DOCUMENTATION Clinical examination forms and written consent proformas have been

published, and it may be advisable for the GDP to use such forms if possible.23 As a minimum the TMJ status and signs of parafunctional habits should be documented. It is our policy to provide an information leaflet advising patients on what to expect when wearing the appliance and how to maintain it (Figure 26). Appliance effectiveness and guarantees of treatment are at the discretion of the clinician, although Healthtec do offer a partial refund if their Therasnore approach does not work.34 It is advisable that a financial agreement for treatment, maintenance and effectiveness is established with the patient before treatment commences. The potential sequelae of untreated OSA (which include stroke, cardiovascular disease and nocturnal mortality) are such that a team approach to treatment, in conjunction with medical specialists, is advocated.18,36,40 Indeed, Lowe considered it mandatory that appliances are made only after a complete medical assessment.2,24 Definitive diagnosis

requires a sleep study to evaluate sleep and breathing patterns and can determine 25 REMOVABLE PROSTHODONTICS the presence, type (central, obstructive or mixed) and severity of any sleep apnoea and effect of appliance treatment. The chairside-derived Epworth Sleepiness Score is a subjective report that may allow differentiation of simple snorers from those with OSA but it is not diagnostic and has limitations of potential bias, falsification and patient literacy.23 The GDP should be aware that snoring can occur with or without OSA and there may be potential medicolegal implications of treatment undertaken unless a diagnosis has been made by a consultant in sleep disorder medicine. Medical defence organizations do recognize the provision of appliances for sleeping disorders and medicolegal cover is, therefore, part of the indemnity.41 2. 3. 4. 5. 6. 7. 8. 9. SUMMARY Aspects relating to the provision of appliances for snoring and OSA by the GDP have been discussed and the

clinical and laboratory stages for construction of an appliance with Odontosil-60 provided. The clinician should decide on the most suitable design for the patient depending on factors such as diagnosis of sleep disorder, cost, parafunctional activity and occlusal registration. A formal medical assessment of the sleeping disorder is advocated before treating such patients. 10. 11. 12. 13. 14. 15. ACKNOWLEDGEMENTS Figure 5 is used with permission of Scheu-Dental, Germany (www.scheu-dentalcom) and Figure 7 courtesy of Pamela Ellis, FTTA in Orthodontics, Charles Clifford Dental Hospital, Sheffield. The appliances shown in Figures 8 and 9 were constructed by Colin Gravenor, Chief Orthodontic Technician, Morriston Hospital, Swansea. Data adapted in construction of Table 1 is used with permission of Professor Alan Lowe, Department of Oral Health Sciences in the Faculty of Dentistry at the University of British Columbia. Personal communications with Rachel Swindells (Healthtec), Rod

Staines (Dental Practice Board) and Iain Cuthbertson (Dental Defence Union) and the Commercial Dental Laboratories in Trent are also acknowledged. 16. 17. 18. 19. 20. REFERENCES 1. Guilleminault C,Tilkian A, Dement WC.The sleep apnoea syndromes. Annu Rev Med 1976; 27: 465– 484. 26 21. Lowe AA. Dental appliances for the treatment of snoring and obstructive sleep apnoea. In: Kryger M, Roth T, Dement W, eds. Principles and Practice of Sleep Medicine, 2nd ed. Philadelphia:WB Saunders Co, 1994; pp.722–735 Bonham PE, Currier GF, Orr WC, Othman J, Nanda RS. The effect of a modified functional appliance on obstructive sleep apnoea. Am J Orthod Dentofac Orthop 1988; 94: 384–392. Meyer JB, Knudson RC. The sleep apnea syndrome Part 2:Treatment. J Prosthet Dent 1990; 63: 320–324 Clark GT, Nakono M. Dental appliances for the treatment of obstructive sleep apnoea. J Am Dent Assoc 1989; 118: 611–617. Lyons MF, Cameron DA, Banham SW. Snoring, sleep apnoea and the role of dental

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