Assessment of filling techniques for primary teeth.

Five techniques for delivering ZOE into straight and curved simulated root canals were investigated for their depthof-fill capabilities. The techniques tested were those using the endodontic pressure syringe, the mechanical syringe, the lentuIo spiral, the JiffyTM Tube, and the tuberculin syringe. Statistical analysis revealed that the instruments of choice for filling straight canals were the endodontic pressure syringe and the lentuIo spiral (P = 0.05). Also, the lentulo spiral was found be the instrument of choice when filling curved canals (P 0.05). When considering the depth-of-fill properties, it was concluded that the lentulo spiral was the best overall ZOE filling tool. The methods selected by practitioners to fill the pulpectomized canals of primary teeth are numerous and varied. The most popular of these filling techniques appear to be those that use the endodontic pressure syringe.’ Endodontic and amalgam pluggers (King et al. 1984), Jiffy" Tubes, (Rifkin 1980), mechanical syringes ~, and a plugging action with wet cotton pellets also have been used with reported success. It was the purpose of this in vitro study to determine which filling technique was capable of satisfying good endodontic principles for depth of fill. Methods and Materials The material of choice for filling pulpectomized primary teeth is zinc oxide and eugenol (ZOE) as stated by Nicholis (1964), Erausquin and Muruzabal (1967), many other investigators. Five of the most common techniques for the delivery of ZOE to the apex of pulpectomized primary teeth were "JiffyTube~Getz-Teledyne; Elk Grove Village, IL. ~ Centrix Omnisyringe-Root Canal Barrel System--Centrix Inc; Stratford, CT. 1Greenberg 1961, 1963; Berk and Krakow 1972; Dannenberg 1974; Frigoletto 1973; Hobson 1970; Krakow and Berk 1965; Rifkin 1980, 1982; Spedding 1973. selected from those currently in use. These methods included those using (1) an endodontic pressure syringe; (2) a mechanical syringe; (3) a lentulo spirald; (4) a Tube; and (5) a tuberculin syringe." A standardized mixture of pure ZOE USP ~ without additives or fillers was prepared for each technique as per the manufacturer’s recommendation and or the technique limitation (Table 1). TABLE 1. Ratio of Zinc Oxide Powder to Eugenol Liquid Technique Ratio in roll1 g Endodontic pressure syringe 0.275 Mechanical syringe 0.450 Lentulo spiral 0.400 Jiffy tube 0.400 Tuberculin syringe 0.400 The difference in the consistencies of the ZOE mixtures was attributable to the physical limitations of the different techniques. The same mixture ratio could therefore not be used in every technique. A triple beam balance~ was used to measure each gram of zinc oxide powder. A tuberculin syringe was used to dispense the corresponding amount of eugenol liquid. The mixtures were spatulated on a dry glass slab at room temperature (68°F) for 45 sec and then placed into identical canal simulation molds ~ (Fig 1, next page), using one of the five techniques. Two canal configurations were tested -straight and curved. Each straight-canal mold contained 24 total canals, each measuring 15.5 mm in length by 0.25 mm in diameter at the orifice. Each curved-canal mold con’ Pulpdent Root Canal Pressure Syringe--Pulpdent Corp of America; BrookLine, MA. Lentulo spiral ISO 25-~Premier Dental Products; Philadelphia, PA. Tuberculin syringe 26g 3/8"--Becton-Dickinson Co; Rochelle Park, NJ. ~Zinc Oxide and Eugenol U.S.P.--Sultan Chemists Inc; Englewood, NJ. Ohaus Triple Beam Balance, cap. 2610 g-~Ohaus Scale Corp; Florham Park, NJ. Canal molds, Ransom and Randolph Dynatrak Self-Study course~The LD Caulk Co-Division of Dentsply International Inc; Milford, DE. PEDIATRIC DENTISTRY: SEI’rEMBER1987/VoL. 9 No. 3 195 tained 22 total canals, each measuring 12.5 mm in vertical length and 0.25 mm at the canal orifice (Fig 2). Both canal types would snugly accommodate a size 15 endodontic file.' A direct view of the canals in the clear plastic molds 0.25 0.25 FIG 1. Straight and curved canal simulation molds. was prevented by covering them with masking tape. This discouraged operator bias and allowed a true comparison to in vivo conditions. Each technique was repeated under identical conditions seven times to develop operator proficiency, then preformed again 17 times each in the straight canals and 15 times each in the curved canals a minimum of one week later. This entire procedure was completed a total of 24 or 22 times depending on the canal configuration being tested. The masking tape then was removed from the molds and each filled canal measured to the greatest vertical depth using a standard Boley gauge and a 3x optical magnifier. The technique for the placement of the standardized mixtures into the simulated canal molds was as follows: 1. Endodontic pressure syringe—Using the technique described by Greenberg (1963) and following the manufacturer's recommendation, the standardized mixture was injected into the simulated canals. The mechanical nature of the pressure syringe (which operates by a screw mechanism) expressed the mixture through a 30gauge needle. The needle was inserted into the simulated canal until wall resistance was encountered. Using a slow, withdrawing-type motion the needle was withdrawn in 3-mm intervals with each quarter turn of the screw until the canal was visibly filled at the orifice. (A 30gauge needle was selected for filling primary teeth if the canal was able to accommodate a standard size 15-30 endodontic file.) 2. Mechanical syringe — The standardized ZOE mixture was loaded into the syringe as per the manufacturer's recommendation and expressed into the simulated canal with continuous pressure via a 30-gauge needle while withdrawing the needle. The pressure was generated by the mechanical lever action of the trigger grip which then was transferred to a plunger and in turn ' Endodontic file, size 15—Union Broach Co Inc; Long Island City, NY. FIG 2. Measurement and dimensions of simulated canals. expressed the ZOE out of the needle. 3. Lentulo spiral — A 25-mm lentulo spiral was selected and used to deliver the standardized mixture of ZOE into the simulated canal. The latch-type lentulo was placed on a contra-angle, slow-speed handpiece and operated in reverse to pick up the material. The lentulo then was slowly inserted into the canal and the material deposited in the forward position until the canal appeared visibly filled at the orifice. It then was removed with a pumping action while still in the forward position. 4. Jiffy Tube — The standardized mixture of ZOE was back-loaded into the tube. The tube tip was placed into the simulated canal orifice and the material expressed into the canal with a downward squeezing motion until the orifice appeared visibly filled. 5. Tuberculin syringe—The standardized mixture of ZOE was back-loaded into the syringe. The syringe utilized a standard 26-gauge, 3/8-inch needle. This was the smallest of the most common needles used for the tuberculin syringe. The material was expressed into the canal by slow finger pressure on the plunger until the canal was visibly filled at the orifice. Following data collection as previously described, the statistical analysis was performed. The mean and standard deviation of each individual group was determined. A two-way analysis of variance with unequal subclass sizes was used in conjunction with a Student's f regression analysis to provide both intragroup and intergroup comparisons.