 Centric jaw relation records are an essential component of the materials submitted to the regional dental activity for the fabrication of various prosthodontic appliances. The proper preparation of these records is crucial to the final success of the appliances. When preparing centric jaw relation records, it is necessary to recognize that specific dentulous and edentulous situations dictate the use of specific record bases. These bases, in turn, dictate the appropriate methods to be employed as well as the types of materials to be used. In view of the special problems associated with receiving materials by mail, the RDA has designed specific packaging procedures. The RDA also highly recommends certain materials and methods for the preparation of centric jaw relation records. We will discuss the materials and procedures for obtaining centric jaw relation records associated with the fabrication of complete dentures and removable partial dentures. The records associated with fixed partial dentures are discussed in the second videotape in this series. When complete dentures are required, there are, of course, three basically different dentulous and edentulous situations that are possible. When both the maxillary and mandibular arches require complete dentures, it is suggested that auto-polymer resin be used as the material for the record base and that either modeling plastic, plaster, or zinc oxide eugenol paste be used as a recording material. The base plates and wax rims are tried in the mouth to check for stability on the edentulous ridges. The maxillary rim is adjusted to meet the aesthetic requirements regarding anterior tooth position and both rims are adjusted as needed according to the determined occluding vertical dimension. A vertical line should be cut into the maxillary wax rim to denote the midline and to act as a visual reference when the patient closes to the previously determined centric position. The patient is instructed to open and close several times to ensure that centric closure can be repeated. The maxillary wax rim is left intact except to cut several V-shaped notches in each side in the bicuspid first molar region. These notches will serve to index the recording material as the patient closes into it. The mandibular wax rim is cut away to a depth of 2 to 3 millimeters except for a small section anteriorly which will be the centric and vertical stop. This material is removed to provide adequate room for the recording material. The mandibular rim is removed from the mouth and the recording material is placed on the rim. It is then replaced in the mouth and the patient is instructed to close and to remain in that position until the recording material has become set. Excess material is trimmed away with a sharp knife so that there will be nothing to falsely guide the patient back to that position when the rim is replaced in the mouth. If the record is not trimmed, the patient will easily be guided back to the previously recorded position even though that position may not be correct. The trimmed record is put back into the mouth for verification. If the patient closes easily into the record without any deviation, it indicates that the patient can repeat the record and implies an accurate centric jaw relation record. The centric relation at the occlusal vertical dimension is recorded with the use of positive keys. When the maxillary arch requires a complete denture and the natural teeth of the mandibular arch are present, the same materials are recommended for use as when both arches require complete dentures. However, the methods for these situations are different. When natural mandibular teeth are present, centric relation is recorded at the occluding vertical dimension with recording material in the first molar and second bicuspid region only. When removable partial dentures are required, there are several basic situations possible. The partial dentures may be opposed by natural teeth or by another partial denture. Furthermore, in each situation the partial denture may be tooth-borne or free-end. In the case of tooth-borne partial dentures, materials are not necessary to make the centric jaw relation records because centric occlusion can be determined on the cast by means of tooth contact of the remaining teeth with the opposing teeth. The centric occlusion should be recorded on the cast with three widely spaced vertical witness lines which are placed on the labial and buckle surfaces of the opposing teeth. For free-end partial dentures, either unilateral or bilateral, auto-polymerizing resin should serve as the material for the record base. A removable partial denture framework can also serve as the recording base after it has been properly fitted to the mouth. Plaster or zinc oxide eugenol, which are both truly plastic in their liquid state, are recommended for the recording material. After the framework has been fitted to the mouth, acrylic bases with wax rims are attached. When the opposing arch is to be restored with a complete denture, centric relation and the occluding vertical dimension are determined according to the doctor's preferred method. We have used a small interior stop made of modeling plastic to record this position. It is highly visible, the material sets hard and thus acts as a positive check when doing the subsequent steps. Several v-shaped wedges are cut into the maxillary wax rim in the bicuspid first molar areas. These wedges will make positive indices in the recording material. It is also advisable to place some mechanical retention on the lower rim to hold the recording material since neither plaster nor zinc oxide eugenol will adhere well to wax. The maxillary base plate is placed back into the mouth. The recording material is prepared, placed on the wax rims, and the framework is also placed in the mouth. Here we are using impression plaster. The patient is instructed to close until the lower anterior teeth have seated into the anterior centric stop. The doctor must observe carefully to ensure that this occurs smoothly without any deviation or deflection which might indicate that the patient is not closing correctly. The recording material is allowed to set completely. The appliance frame and record is removed from the mouth and carefully trimmed with a sharp knife. It is then returned to the mouth to verify accuracy. All of the procedures that we have discussed as well as those which we will discuss in the second videotape in this series have been designed to aid the RDA in fabricating the prosthodontic appliances that will meet our patient's needs.