Fixed Prosthodontics Lecture 10: Interocclusal Record PDF

Fixed Prosthodontics Lecture No:10 Interocclusal Record (Bite Registration Record) Lecturer: Dr.Lana Bahram Khidher BDS,Ph.D in Prosthodontic Interocclusal Record (Bite Registration Record): Bite registration : is a technique by which the dentist transfer t...

Fixed Prosthodontics Lecture No:10 Interocclusal Record (Bite Registration Record) Lecturer: Dr.Lana Bahram Khidher BDS,Ph.D in Prosthodontic Interocclusal Record (Bite Registration Record): Bite registration : is a technique by which the dentist transfer the relation ship between the upper and lower jaw from the patients mouth to the articulator. Bite registration allows the dentist to observe accurately tooth contact, occlusal discrepancies and to fabricate restorative procedure for the patient without changing in patients occlusion.  Its important to establish and transfer the relation ship between the maxillary and mandibular dental arches that exists when the condylars are in the posterior superior position in the glenoid fossa to an articulator using a bite registration materials. When enough teeth are present in both dental arches we can transfer the relation by hand articulation of the casts. i.e., no bite registration is needed in such cases, so we can occlude the opposing casts by hand, then we mount them on the articulator If the remaining teeth are insufficient to produce hand articulation of the casts, we have to record the bite by using either of the followings: 1. Pink base plate wax , or compound). 2. Bite registration paste (ZOE,Silicone). 3. Bite rim or occlusal rim Bite Registration Materials Requirements of material used: 1- It should be stable (have little or no dimensional change during setting. 2- It should give accurate record of occlusal surface and incisal edges of the teeth. 3- It should not affect normal closing of the mandible. 4- The material should remain rigid after setting. Its better to check the inter occlusal record several time inside patient mouth.  Centric relation is the physiological position of the condylar head of the mandible (without stress) from which all other movement is initiated. Centric relation is taken when no enough occlusal stops are left after teeth preparation especially in cases of full mouth rehabilitation of fixed partial denture. Including distal terminal abutments unilaterally or bilaterally. In centric relation it must not perforate the registration material. Centric occlusion : Teeth to teeth relation ship it is the maximum occlusal contact or intercuspation irrespective of condylar position. Maxillary and mandibular teeth should contact in harmonious manner that allows optimum function, minimum trauma to the supporting structure and an even distribution of load through the dentition. Centric occlusion can be taken when there are enough occlusal stops after preparation for a crown and bridge. In recording the centric occlusion with maximum intercuspation the record material must show perforation in area of contact teeth. Dowson's technique: Dowson's in 1974 suggest to place the dental chair in reclined position and the patient's head fixed by the dentist standing behind the patient with both thumbs on the chin and the fingers resting on the inferior border of the mandible. Then by gentle downward pressure by thumbs and upward pressure on figure the patient's mandible will bring into centric and let the patient bite on the registration material. Methods of inter-occlusal record: 1. If enough teeth are present in both upper and lower arches to stabilize their relation ship. No bite registration is needed we can transfer the relation by hand articulation. 2. If the remaining teeth are insufficient to provide hand articulation of the cast we can use: -Pink base plate wax or alu-wax (wax reinforced with fiber) Apiece of wax is placed on the maxillary teeth and ask the patient to close in centric relation then the wax is removed and placed in water for cooling. 3. Occlusal rims: - When insufficient number of the teeth are present to stabilize the cast. A bite rim must be made using a base plate wax to replace the remaining teeth.( this rim is necessary when restoring anterior teeth and the posterior teeth are missing leaving unstable opposing cast)  If the patient is under local anesthesia or conscious sedation it makes a procdure much more difficult for patient to provide the dentist with the correct registration. patient who have been anesthetized with mandibular blocks will lose their proprioception ability into centric occlusion Glass bite material: this material is introduced between the dental arches with the special cannula and can be applied ideally between the dental arches much faster and more easily than other materials. Its stabile and transparent. Luxa bite rigid bite registration advantages: 1- Highly accurate to the models 2- Can be used with or without bite registration trays 3- No interference with closure of teeth 4- Fast setting and easy to trim 5- Resist normal temporary variations (better than wax) 6- No compression on mounting Bite registrations for CAD/CAM procedures Bite registration can be digitally recorded in the same way as that used for digital impression, both procedures are employed in conjunction with the computer-aided design/computer-aided manufacturing (CAD/CAM). Digital Bite registration are taken either: Indirectly using extra oral scanner (In lab). Directly in the mouth at chairside using an intraoral digital camera (In office). In order to determine the occlusal relationship, for indirect scanning technique, an antagonist bite registration is required. Being able to directly capture images of this bite record with a scanning device or camera without having to apply a contrast medium. while for direct technique, In order to determine the occlusal relationship the image of occlusal relation of opposing dental arch is capture directly from the inside of patient s mouth using intra oral digital camera without the need for of any material for bite registration record.