Clinical Tip for Protrusive Records

Oral rehabilitation involves a sequence of steps that must be followed in a highly judicious manner. The success of any prosthetic rehabilitating treatment depends on several aspects related to the precise mounting of casts in the articulator. When the maxillary and the mandibular casts are to be held together in a stable and reproducible manner, a tripod of vertical support as well as a satisfactory horizontal stability is necessary. Tripod of vertical support is essential to prevent the rocking of the casts during mounting. Horizontal stability is essential to prevent the horizontal rotation or translation between the casts and is generally present when good intercuspation exists between the two opposing arches. An interocclusal record is mainly used to achieve the horizontal stability¹. Interocclusal records are used for recording both centric relation and protrusive for transferring it to articulator and program it, so that it can mimic patient’s condylar guidance in glenoid fossa.

Protrusive interocclusal record is defined as registration of the mandible in relation to the maxillae when both condyles are advanced in the glenoid fossa.² The rationale for recording protrusive mandibular movement is twofold: diagnostic casts mounted on an articulator and adjusted with an accurate protrusive record are more reliable and restorations made on a programmed articulator closely reflect patient movement. The preferred technique or material to record protrusive movement is debatable. Techniques to record condylar inclination include radiographic interpretation, extraoral tracings, and intraoral recording material³. There are various methods to guide patient in protrusion, we can also use mirror for guiding patient in protrusion for injecting material like polyvinylsiloxane for making protrusive records.

Intraoral registrations may compromise accuracy because of dimensional instability of registration materials. The most common material used for interocclusal records is wax. Millstein et aL found that adding a 0.05 mm thick aluminum laminate between wax wafers impregnated with copper particles improved the accuracy compared with baseplate wax.⁴ The Coprwax aluminum laminated, metalized wax wafer has demonstrated less distortion than similar wax recording materials. Polyvinyl siloxane is an addition-reaction silicone without by-products that possesses dimensional stability. Polyvinyl siloxane has earned acceptance as an impression material and now is marketed as an interocclusal registration material.⁵ Here are some clinical steps to be followed for making protrusive record to assist in programming of articulator.

1. Useface mirror to guide patient in protrusion and take midline as guide for 
2. Thenbleed the bite registration material and inject onto the triangular space created and join the both ends.
3. Theninstruct the patient to swallow saliva as you inject so as to press material lingually against the teeth and massage material buccally.