ACCESS PREPARATIONS

Access is an essential element to successful endodontics. Preparing the endodontic access cavity is a critical step in a series of procedures that potentially leads to the three-dimensional obturation of the root canal system. Access cavities should be cut so the pulpal roof, including all overlying dentin, is removed. The size of the access cavity is dictated by the position of the orifice(s). The axial walls are extended laterally such that the orifice(s) is just within this outline form. The internal walls are flared and smoothed to provide straightline access into the orifice and the root canal system. Additionally, access preparations are expanded to eliminate any coronal interference during subsequent instrumentation. Access objectives are confirmed when all the orifices can be visualized without moving the mouth mirror. Ideally, endodontic access cavities should parallel the principle of restorative dentistry where the axial walls of a “finished” preparation taper and provide draw for a wax pattern. Cleaning and shaping potentials are dramatically improved when instruments conveniently pass through the occlusal opening, effortlessly slide down smooth axial walls and are easily inserted into the orifice. Spacious access cavities are an opening for canal preparation.

When dealing with tooth-colored restoratives, a #2 or #4 round bur diamond (Dentsply Tulsa Dental) should be selected to initiate the access preparation. A #2 round bur diamond is generally selected for bicuspid or anterior teeth, whereas the #4 is usually selected for molar teeth. On the other hand, when dealing with alloys or metallic restorations, a transmetal bur is useful as it reduces unwanted vibration. Finally, access cavities are best prepared through dentin utilizing surgical length #2 or #4 round burs (Dentsply Tulsa Dental). The added length of these rotary cutting tools push the head of the handpiece further away from the occlusal surface thus providing the clinician with a better line-of-sight and allowing light to more optimally illuminate the tooth preparation.

“Finishing” the access cavity is performed with surgical length tapered diamonds (Dentsply Tulsa Dental). When the access cavity is finished the walls are flat, smooth and uniformly refract light. Highspeed surgical length round burs can be utilized to reach deep and remove secondary dentin which at times overlies and obscures an orifice. In other instances, a clinician may desire the safety and control that is afforded by a slowspeed handpiece and utilize the Mueller bur (Brasseler) to carve away calcific dentin. A Mueller bur is a latch-type surgical length carbide 1/2 mm round bur whose extended length improves deep vision, small size encourages safe access and slowspeed rotation promotes control when operating in confined areas. Fortunately, the ProUltra SINE ultrasonic instruments (Dentsply Tulsa Dental) have essentially eliminated the use of bulky handpieces and oversized rotary cutting tools traditionally used in access refinement.

Gates gliddens may be used to flare or “face-off” the canal orifices. This procedure simplifies subsequent cleaning and shaping procedures by quickly establishing a smooth glide path through the access chamber into the root canal system. The specific gates glidden (GG) selected is dependent on the size of the orifice; however, typically in posterior teeth, the GG-4 would be an optimal size (1.10 mm). In a more calcified orifice(s), small sized stainless steel hand files may first be employed to create sufficient space to facilitate using a GG-1, 2 or 3. Oftentimes, the use of smaller sized GG’s promotes the safe use of larger sized GG’s. The selected GG is then placed just in the orifice and, once activated, the head of the handpiece is moved in an orbital arc above the GG/orifice pivot point. This method of use begins to flare the orifice. The belly of the GG is used to refine, smooth and blend the coronal aspect of the canal into the axial walls. This technique produces a smooth flowing funnel which creates ease in the subsequent placement of small sized 10 and 15 stainless steel files. In summary, by facing-off the orifice, subsequent endodontic procedures are simplified immediately.

Dentsply Tulsa Dental carries the P5 Ultrasonic unit that I like. You will notice improved performance and, importantly, less tip breakage. Dentsply also carries my ProUltra SINE and ENDO ultrasonic tips which can be utilized for access refinement and/or other endodontic procedures. Following is Dentsply's information:

Dentsply Tulsa Dental (Tulsa, Oklahoma)
Phone: 800-662-1202
www.dentsply.com