Australasian Dentist Issue 92

CATEGORY AUSTRALASIAN DENTIST 71 contributed to mixed clinical outcomes resulting in the original Michigan splint being modified and different splint designs have emerged. The thickness of splints has been evaluated to assess clinical outcomes for different clinical TMDs (Dao et al. 1994, Hegab et al. 1994,Manns et al. 1983,McNeill 1997, Suvinen et al 2003). In general, medium, and thick splints produced better clinical outcomes. Hegab et al. used MRI measurements and clinical outcome and recommended, for an optimal result, splint thickness at the molars to be 4 mm for reducing discs and 6 mm for non-reducing discs (Hegab et al. 2018). Designing lateral guidance in the form of differing types of canine rise fromshallow to extreme angulations (Lundh et al. 1992, Manns et al. 1987, Shupe et al. 1984, Willis 1995) and molar guidance (Graham 1986, Graham1988, Rugh 1989) was researched to evaluate their effectiveness in management of TMDs. In general, steeper canine rises produced better clinical outcomes and molar guidance was also effective in reducing symptoms, as both produced a protective vertico-lateral mandibular movement (Darveniza 2001). This splint design differed in the above studies as it was the only one that measured the length of excursive paths and corresponding overjet and disclusion to arrive at a repeatable and comfortable inclination for canine and protrusive rises. As well, the prior mentioned design elements including thickness were addressed for the following factors: adult or child, worn-down dentitions, deep overbite, predominantly a clencher, type of displaced discs, Angle’s skeletal type, and extreme bruxing and crossover. Timing of splint therapy To this point, there has not been any universally agreed upon, clearly enunciated, protocol for the number of splint adjustments and time between these adjustments for occlusal splint therapy in the management of TMDs. Ramfjord and Ash in the 1966 and 1971 editions claimed that ‘after two to three weeks the muscles are usually relaxed, and occlusal adjustment can be refined to the point where the splint is no longer needed’. In the 1983 edition splint adjustment was recommended the day after fitting if pain or discomfort increased, then in 5-7 days and periodically thereafter. In 1994 Ramfjord and Ash claimed optimal centric relation may take several months of splint adjustments every two or three weeks. McNamara et al. recommended three to five splint adjustment appointments of a Michigan splint to achieve reproducible contacts at the final visits, but no time frame was recorded. These pinpoint contacts were largely confined to the posterior occlusion and contact was ‘avoided for the cuspids and perhaps some anterior teeth’(McNamara et al. 1982). Dylina suggested wearing the splint 24 hours a day except when eating for a three- to-six-month period and recommended a six-splint adjustment protocol of 1, 3, 7, 14, 21 days and a month (Dylina 2002). Hammad et al.2005 suggested wearing the splint 24 hours a day except when eating with weekly adjustments over an eight- week period. Banerji and Mehta 2017 suggested two weekly splint adjustments until occlusal contacts ‘are consistent between consecutive visits and the patient is comfortable’. This paper outlines a qualitative description for fabricating and fitting this splint, and quantitative parameters for designing this splint, following the measurement of 100 ‘Fully Protective Occlusal Splints’.The paper also outlines the number and timing of splint adjustments for ‘Formal Occlusal Splint Therapy’ and summarizes the results of this therapy after treating 200 TMD patients Materials and methods Guidelines for fabricating, measuring, and equilibrating a fully protective occlusal splint Fabrication of the splints was done in the usual manner but with the following salient features: 1. the posterior border of the splint starts 6 mm posterior to the centre of the palatal papilla and angles to the distopalatal corner of the last molar (Fig. 1), 3. with the adjustable jig at a starting vertical dimension a periodontal probe was placed between the buccal cusps of the first molars to measure the space for a future splint thickness. The metal wafers of the jig were cold luted with bees wax and wafers were added or subtracted to achieve the required vertical dimension for the planned splint thickness (Fig. 2), 4. a semi-adjustable or fully adjustable articulator was used andwhere possible the Stratos 300 (Ivoclar) which has a retrusive adjustment for bio-designing early canine rise path, 5. a saliva line was incorporated into the posterior border of the splint, 1.25-1.5 mm deep at the midline and fading out at the first molar, to seal the posterior border and impede any saliva sucking habit (Fig. 3), LINICAL Fig. 3. Secondary model with heavily adjusted saliva line (long arrow) to check the fit of the splint including the completed saliva line (short arrow) with a 1.25 – 1.5 mm thickness at the midline and fading out to 0.5 mm at the first molar. Fig.1 Centric stops in the posterior region and open bite of 0.25-0.5 mm in the canine and 0.5-1.0 mm in the incisor regions to create an occlusal freedom space to accommodate mandibular repositioning. Fig. 2 DeLar jig and wax record taken with a posterior open bite of about 5 mm at the first molar regions. 2. the DeLar centric record system (DeLar Corporation, Lake Oswego, Oregon, U.S.A.) with an adjustable height anterior jig (multiple wafers of malleable metal) was used in unison with an indented (to accommodate the jig) wax wafer to record centric relation (Fig. 2), 6. the anterior splint outline was waxed 3 mm or more onto the labial surface of the central incisors and canines for stability during parafunction and 1.5-2 mm thick peripherally. This peripheral thickness allowed room for internal grinding during fitting when the path of insertion was compromised (Fig. 4), and 7. acrylic resin hooks were incorporated into the undercuts of the buccal gingival