0099-2399/97/2310-0639503.00/0 JOURNALOF ENDODONTICS Copyright © 1997 by The American Association of Endodontists
Printed in U.S.A. VOL. 23, NO. 10, OCTOBER1997
Sealing Ability of Several Restorative Materials Used for Repair of Lateral Root Perforations Francesco Mannocci, MD, DDS, Alessandro Vichi, DMD, and Marco Ferrari, MD, DDS, PhD
Amalgam, IRM, Vitremer, Bisfil, and Ana Norm Liner were evaluated for repair of experimentally induced lateral perforations. Eighty-five sound, mandibular, and maxillary molars, extracted for periodontal reasons, were selected for this study. The sample teeth were randomly divided in five groups with 15 specimens each. Ten teeth were used as control groups. After the perforations were filled with the abovementioned materials, the teeth were immersed in a 2% methylene blue solution for 48 h, sectioned, and dye penetration was measured. The results indicated that Bisfil 2 B provided a significantly better seal than the other materials.
It is well known (11) that the prognosis of both surgical and intracoronal perforations is much worse in the coronal third of the root than in the apical two thirds, and it is well known too (12, 13, 14, 15) that the new generation enamel-dentin adhesive systems permit a consistent improvement of bonding to dental structures. The purpose of this study was to compare by dye leakage test, the sealing ability of some new generation dentin-enamel bonding systems and composite materials with that of amalgam and IRM in lateral perforations experimentally induced in the coronal third of extracted human teeth.
M A T E R I A L S AND M E T H O D S Eighty-five mandibular and maxillary molars extracted for periodontal reasons were used in this study. The teeth were basically prepared as described by Lee et al. (7) with some modifications. A coronal access cavity was prepared in each tooth. The canals were located with an endodontic explorer, a perforation was then made from the mesial surface of the pulp chamber toward the mesial surface of the root with a slow speed #2 long shank round bur at an angle of about 45 degrees to the long axis of each tooth. The prepared teeth were than placed in silicone blocks (Provil P Soft, Bayer Dental, Leverkusen, Germany). The wall of the blocks facing the perforation was cut with a Bard-Parker n ° 15 knife. In this way, a sort of pocket was created in front of the perforation to permit possible extrusion of the filling material. On the top of the pocket a piece of sponge was applied. The sponge was kept wet by an assistant with a water syringe while the operator was working on the tooth isolated with a rubber dam. This setup provided a model simulating a clinical situation in which underfilling or overfilling of the repair material is not observable by the operator. The 85 teeth were randomly divided into five groups of 15 samples each and two other groups of five samples each as controls. The perforations were filled as follows: Group 1 with amalgam (Tytin, SS White Co, Philadelphia, PA), Group 2 with IRM (De Trey-Dentsply, England), Group 3 with Vitremer (3M, St Paul, MN), Group 4 with Bisfil 2B (Bisco, Itasca, Ill), and Group 5 with Ana-Norm Liner (Nordiska Dental AB, Helsingborg, Sweden). Five teeth were prepared in the same manner as the experimental group and received no fillings (Group 6): these teeth served as positive controls to show that dye could flow into the preparations. Five unprepared teeth were covered with nail polish (Group 7).
Root perforations occur during endodontic treatment as a result of procedural mistakes during access preparation and canal or post space preparation. One of the main objectives of perforation treatment is to obtain a perfect seal between the dentinal defect and the repair materials. Different materials have been used for intracoronal or surgical perforation treatment, both in clinical and in experimental situations. Nicholls used zinc oxide eugenol (1); Harris (2) obtained very good results using Cavit. In other studies, amalgam was found better than Cavit and calcium hydroxide in experimental animals (3). In a recall evaluation, amalgam was found superior to guttapercha (4). Super Eba cement, basically a reinforced zinc oxideeugenol, was also tested with success (5). More recently Dazey and Senia (6) reported that light curing calcium hydroxide was better than Ketac-Silver. MTA, whose compounds are tricalcium silicate, tricalcium alluminate, and tricalcium oxide silicate was found better than amalgam and IRM (7). To avoid overextension of filling materials, which could cause interference with periodontal reattachment, Auslander (8) inserted amalgam over an indium foil; Himel and Alhadayni created a plaster of Paris barrier against which amalgam or glass ionomer liner was condensed (9). Histological studies demonstrate unfavorable tissue response at the treatment site: Balla (10) found no hard tissue formation but he did find inflammation in the furcation area after repair with tricalcium phosphate, hydroxilapatite, amalgam, and Life.
Mannocci, et al.
These teeth were used as negative controls to show that nail polish painting provided a good barrier against dye penetration. Groups 1 and 2: Amalgam and IRM were placed into the perforation by a Messing gun (Union Broach, Emigsville, PA) through the access cavities in small increments. Both amalgam and IRM were then gently condensed into the perforations with a plugger. The access cavities of teeth in Groups 1 and 2 were filled with the same materials used to fill the perforation. Group 3: the walls of the perforation and of the access cavities were etched with 35% orthophosphoric acid for 20 s, washed with water spray, and dried thoroughly. 3M Vitremer primer was then applied with a brush to the perforation and cavity walls for 30 s. The primer was then dried for 15 s and light cured for 20 s. Vitremer powder and liquid were mixed following manufacturer's instructions; the mixed glass ionomer was syringed into the perforation, condensed with a damp cotton pledget, and light cured for 40 s. The access cavities were then filled with the same material in three increments, each increment was light cured for 40 s. Group 4: the walls of the perforation and of the access cavity were etched with 10% orthophosphoric acid for 15 s, washed thoroughly, and dried for 3 s to remove excess water, keeping the dentin wet. Five consecutive coats of All Bond 2 Primer (Bisco) were then applied, and all surfaces were dried for a few seconds with an air syringe. An equal volume of All Bond 2 Dentin/Enamel Bonding Resin and Pre-Bond Resin were mixed and brushed onto perforation and cavity surfaces. Bisfil 2B (Bisco) base and catalyst were mixed on a mixing pad, loaded into a syringe, and injected into the perforation. The composite was allowed to polymefize, then the access cavity was filled with the same material. Group 5: the walls of the perforation and of the access cavity were etched with 35% orthophosphoric acid gel, thoroughly washed, and gently air-dried; Ana Norm Bonding White and Red (Dentin primer) were mixed and applied to the walls for 30 s with agitation. A thin layer of Ana Norm Bond Black was then applied onto the perforation and the cavity walls and polymerized for 20 s. Ana Norm Liner was then injected into the perforation and light cured for 20 s. The access cavity was filled with ZI00 Hybrid composite resin (3 M) in three increments. Each increment was light cured for 40 s. The light curing material in all the experimental groups were cured from the occlusal surface. The teeth were kept in saline solution for 4 weeks. The surface
Journal of Endodontics TABLE 1. Average leakage with the various materials
Average leakage (in mm) Range
VIT: Vitremer (3M); BIS: Bisfill 2B (Bisce); AMA: amalgam (rytin SSW); IRM: IRM (Dentsply); ANA: Ananorm liner (Nordiska).
TABLE 2. Frequency of overfilling with the various materials VIT Incidence % Average leakage when overfilled (in mm)
20 53 2.16 1.06
VIT: Vitremer; BIS: Bisfil; AMA: Amalgam; IRM: IRM; ANA: Ana Norm Liner.
TABLE 3. Frequency of underfilling with the various materials VIT BIS AMA Incidence % Average leakage when underfilled
IRM ANA 0 1.33
VlT: Vitremer; BIS: Bisfil; Area; amalgam; IRM: IRM; ANA: Aria Norm Liner.
of each tooth, except 1 to 2 mm around the perforation site, was double coated with nail varnish. The teeth were placed in a 2% methylene blue solution for 48 h. The specimens were removed from the dye solution, washed, and dried with compressed air. To evaluate the depth of dye penetration, each tooth was ground parallel to its long axis to expose the filled perforated site using a large diamond bur in a high-speed handpiece underwater spray as described by Lee (7) (Fig. 1). For microscopic observation 20-fold magnification was used. Linear dye penetration was double blind measured by two different observers from the external root surface into the access cavity of each tooth. A Newman-Keuls multiple comparison test at the 0.05 significance level was used to evaluate the statistical difference between the five experimental groups.
FIG 1. A ground tooth, from Vitremer group, which shows a considerable amount of leakage, both along the perforation walls (small arrow) and into the dentinal tubules, (big arrow).
All experimental groups demonstrated dye penetration to varying degrees. Positive controls showed complete dye penetration while negative controls showed none. Average linear penetration for the five experimental groups is shown in Table 1. Bisfil 2B leaked significantly less than the other four materials (p < 0.05). There were no significant statistical differences between Vitremer and IRM group and between amalgam and Ana Norm Liner group. Vitremer and IRM leaked significantly less (p < 0.05) than amalgam and Ana Norm Liner. The frequency of overfilling and underfilling at the perforation sites is shown in Tables 2 and 3. Bisfil 2B showed the highest rate of overfilling followed by amalgam and Ana norm liner. IRM and Vitremer showed the lowest rate of overfilling. Vitremer showed the highest rate of underfilling, followed by amalgam and IRM. No underfilled samples were found in the Bisfil 2B and Ana Norm Liner groups.
Vol. 23, No. 10, October 1997
When dye penetration was measured in overfilled sites in each group, the Bisfil 2B group still had the least dye penetration (p <
0.05). The evaluation of dye penetration in underfilled sites in each group showed that Bisfil 2B and IRM had the least dye penetration (p < 0.05).
DISCUSSION The use of dyes is one of the commonest methods of studying microleakage. Recently, the relevance of leakage studies in endodontics has been questioned (19), but (20) dye leakage evaluation still remains the best initial test for the screening of sealing ability. Amalgam and IRM are among the most widely used materials for repair of lateral root perforations. The depth of dye penetration with these two materials was considerably higher than that obtained by Lee (7) in a similar experiment. This could be due to the different model used to simulate clinical conditions and, in particular, to the continuous moisture present in the perforation area in our experiment. IRM leaked significantly less than amalgam, and this is in contrast with a previous study (7). Our amalgam could be different from the one used in that study, in which the amalgam used is not specified. Vitremer, Bisfil 2B, and Ana Norm Liner have been applied to perforation walls after etching procedures and application of dentinal adhesives that should give a good bonding. It is well known that this new generation of adhesive materials provides removal of smear layer, inducing structural changes in the dentinal surface creating a retentive interdiffusion zone (the so called hybrid layer) between the two substrates and forming resin tags with adhesive lateral branches both in vivo and in vitro (15, 16, 17, 18). Notwithstanding this, the results obtained with Vitremer and Ana Norm Liner were not significantly better than those obtained with amalgam and IRM. It is possible that an incomplete polymerization of the light curing adhesives occurred in the Vitremer and Ana Norm Liner groups because of the distance between the light source, which was on the occlusal surface, and the perforation walls. Another possible reason for the results obtained with Vitremer and Ana Norm Liner is the polymerization of the access cavity filling materials, which could have led to the detachment from the perforation walls of the previously polymerized perforation filling material. In the Bisfil 2b group, a self-curing material was used in combination with a dual curing adhesive (All Bond 2 Dentin Enamel Bonding Resin and Pre-Bond Resin mixture). This could explain the good results obtained with this material. Overfilling occurred mostly in the Bisfil 2b group. The values of dye penetration when overfilling occurred were not significantly different from the overall dye penetration values of the respective materials. Overfilling could be a potential problem when using All Bond 2 and Bisfil 2B in sealing root perforations. Another problem could be the numerous steps required for the application of these
Root Perforation Fillings Leakage
materials. Additional in vivo studies are needed to evaluate this issue and to determine long-term clinical results and if interference with periodontal reattachment occurs in the perforation areas sealed with the composite materials used in this study. Dr. Mannocci is visiting professor at Siena University, Italy. Dr. Vichi is clinical professor of Restorative Dentistry, Siena University. Dr. Ferrari is clinical professor of Restorative Dentistry, Siena University and Adjunct associate clinical professor of Restorative Dentistry, Tufts University, Boston, MA. Address requests for reprints to Dr. Francesco Mannocci, Cagidiaco E. St. Ass., Piazza Attias 19, Livorno-ltaly-57120.
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