| Abstract|| |
Objective : The present study was undertaken to evaluate the effect of hydroxyapatite (HA) and calcium sulfate (CS) on the sealing ability of mineral trioxide aggregate (MTA) and light cured glass ionomer cement (LC GIC) when used to repair furcation perforations.
Materials and Methods : The study was conducted on 70 human molars. Sixty teeth with furcal perforations were randomly divided into six groups of 10 teeth each and repaired with MTA or LC GIC either alone or over an internal matrix, i.e., CS or HA. Access openings were filled with composite resin. Five teeth with unrepaired perforations were used as positive controls and five teeth without perforations were used as negative controls. The teeth were immersed in a solution of 2% methylene blue dye for 2 weeks. The samples were then sectioned and evaluated for linear dye leakage and analyzed statistically.
Results : MTA showed the best sealing ability followed by LC GIC, MTA + CS, MTA + HA, LC GIC + CS and LC GIC + HA.
Conclusion : Neither of the two internal matrices improved the sealing ability of the repair materials used.
Keywords: Calcium sulfate; furcation perforation; hydroxyapatite; light cured glass ionomer cement; microleakage; mineral trioxide aggregate
|How to cite this article:|
Taneja S, Kumari M. Effect of internal matrices of hydroxyapatite and calcium sulfate on the sealing ability of mineral trioxide aggregate and light cured glass ionomer cement. J Conserv Dent 2011;14:6-9
|How to cite this URL:|
Taneja S, Kumari M. Effect of internal matrices of hydroxyapatite and calcium sulfate on the sealing ability of mineral trioxide aggregate and light cured glass ionomer cement. J Conserv Dent [serial online] 2011 [cited 2019 Apr 21];14:6-9. Available from: http://www.jcd.org.in/text.asp?2011/14/1/6/80722
| Introduction|| |
A furcation perforation results in an inflammatory reaction of the periodontium, which can lead to irreversible attachment loss. If the perforation is not adequately repaired, the prognosis for these teeth is poor. It is important that the material used for the repair provides a good seal and does not cause further tissue damage. To repair furcation perforations, numerous materials have been used that include zinc oxide-eugenol cements (intermediate restorative material and Super-Ethoxy Benzoic acid), glass ionomer cement (GIC), composite resins, resin-glass ionomer hybrids, and mineral trioxide aggregate (MTA).  Furcation perforations may be treated using either an internal or an external (surgical) approach. Ideally, a nonsurgical technique through intracoronal placement of the material to repair the perforation should be used initially. This preserves the periodontium and increases the probability of long-term success.  However, difficulties have been encountered with such an approach, including extrusion of the repair material, inadequate sealing of the defect and lack of biocompatibility of repair materials.  Many attempts have been made to overcome these problems. In 1992, Lemon introduced the "internal matrix concept" for treatment of furcation perforations.  He recommended the use of amalgam for sealing the perforation against a matrix of hydroxyapatite (HA). In modified internal matrix concept, collagen is used as a completely resorbable barrier material and MTA used for sealing of the perforation. Zou et al. found that Collaplug when used as an internal matrix significantly decreased the sealing ability of MTA.
A small-particle HA has been described as an internal matrix for use under repair materials, such as amalgam or glass ionomer, to prevent their extrusion into the periodontal space. However, the effect of HA as a matrix on the sealing ability of MTA has not yet been studied. Plaster of Paris proved to provide a good barrier against the extrusion of the repair materials when it was used to repair furcation perforation in vitro. It has the ability to exclude epithelial tissue from the site of bone formation and has a rapid rate of resorption which coincides with the rate of new bone growth.  Previous studies have reported contradictory findings about the effect of calcium sulfate (CS) on the sealing ability of resin-modified GIC , and MTA.  These conflicting results have prompted the study of CS as a barrier material for the furcation perforation.The purpose of this study was to evaluate the effect of HA and CS on the sealing ability of MTA and light cured glass ionomer cement (LC GIC), when used to repair furcation perforations.
| Materials and Methods|| |
Seventy extracted, intact, non-carious human molars with nonfused and well-developed roots were used in this study. The teeth were stored in physiologic saline containing 0.2% sodium azide. A standardized endodontic access opening was made using a # 4 round bur in high-speed handpiece with water coolant in 65 teeth. Perforation was made on the pulp chamber floor at furcation area using a # 2 round bur in a low-speed handpiece. Teeth were rinsed with water and dried with oil free air. Moist cotton pellets were placed passively between roots in the furcation area and the teeth were kept in an incubator at 37°C for 24 hours to simulate the clinical condition.
Sixty teeth were randomly divided into six groups (n = 10) and perforations sealed as follows.
Group 1 (MTA)
Perforation was repaired with gray ProRoot MTA (GMTA) (Dentsply, Tulsa Dental, OK, USA), which was mixed according to the manufacturer's recommendations. This material was placed with a messing gun and compacted with pluggers. A separate mix was prepared before the repair of each perforation.
Group 2 (MTA + CS)
Perforation was repaired with GMTA over an internal matrix of CS (Neelkanth, Menichem). CS was mixed with sterile water. The mixed putty was placed into the perforation and condensed with endodontic pluggers until a base was created under the perforation. After setting of CS, surface was prepared using a # 33 bur to make a small cavity leaving a base of internal matrix material at the furcation perforation. Perforations were then repaired with MTA.
Group 3 (MTA + HA)
Perforation was repaired with GMTA over an internal matrix of HA (OssifiTM, Equinox, Holland). HA was mixed with normal saline. The mixed material was placed into the perforation and condensed with endodontic pluggers until a base was created under the perforation. After setting of the materials used as an internal matrix, surface was prepared as in group 2 and perforations repaired with MTA.
Group 4 (LC GIC)
Perforation was repaired with LC GIC (Vitrebond, 3M) which was mixed according to the manufacturer's recommendations. The mixed material was carried in small amounts into the pulp chamber on the tip of an explorer and cured when it had apparently sealed the apical end of the defect. The material was placed in approximately 1.5-mm thick increments and light cured. The process was repeated until the material sealed the preparation up to the base of pulp chamber.
Group 5 (LC GIC + CS)
Perforation was repaired with LC GIC over an internal matrix of CS. CS was mixed and placed into the perforation, as in group 2. This was followed by placement of LC GIC over the internal matrix of CS.
Group 6 (LC GIC + HA)
Perforation was repaired with LC GIC over an internal matrix of HA. HA was mixed and placed into the perforation, as in group 3. This was followed by placement of LC GIC over the internal matrix of HA.Five teeth with unrepaired perforations were used as positive controls and five teeth without perforations were used as negative controls.
In groups 1-3, moist cotton pellets were placed over the repair materials and sealed with cavit-G. After 4 hours, moist cotton along with cavit-G were removed. The access openings of all experimental teeth were sealed with light cured composite resin (Silux plus, 3M). Teeth were kept for 72 hours at 37°C and 100% humidity in an incubator. All teeth were painted with nail varnish except near the perforation in the furcation area and then immersed in 2% methylene blue dye for 2 weeks at room temperature. After removal from the dye, the teeth were washed thoroughly in tap water and sectioned through repaired perforation parallel to the long axis of the tooth with safe sided diamond disk.Sections were examined under stereomicroscope to evaluate the level of dye penetration. Each sample was measured for linear dye leakage. In each section, perforation walls were measured from the pulp chamber floor to the apical end of the sealing material, i.e., MTA or LC GIC. Leakage was measured on each section as the dye penetrated through the dentin-sealing material (MTA or LC GIC) interface from the apical level of the sealing material toward the coronal end of the perforation. The percentage of the perforation wall having greater dye penetration in relation to the entire dentin-sealing material interface was calculated for each tooth by using the formula given below. The formula has been derived from the methodology given by Alhadainy et al.
where L1 is the total length from the pulp chamber floor to the apical end of the sealing material and L2 is the length of dye penetration from the apical end of the sealing material toward the coronal end of the perforation.
The results of the dye leakage study were analyzed by one-way analysis of variance (ANOVA) followed by Fisher Least Significant Difference (LSD) test to see significance among the various groups. Under the LSD test, all pairwise comparisons between the group means were carried out by paired t test, where no assumptions were made for the error rate of multiple comparisons.
| Results|| |
Under the conditions of this study, all experimental groups demonstrated dye penetration to varying degrees. Positive controls showed complete dye penetration through the entire preparation, whereas the negative controls showed none.
Mean dye penetration and its standard deviation along with its number of observation in each experimental and control group were compared and the results are tabulated in [Table 1]. There was a highly significant difference between mean percentage of dye penetration across all the groups, with P values <0.001 and F > 3242. The results of multiple range test indicate highly significant difference (P < 0.001) for all the groups except the difference between MTA + CS and LC GIC which was statistically significant (P < 0.005).
One way ANOVA (P < 0.001, F < 3242); Fisher LSD test ( P < 0.001 highly significant, P < 0.005 significant)
| Discussion|| |
Sealing ability of the repair materials and their extrusion into furcation areas are considered major problems when repairing furcation perforations. In the present study, sealing of furcation perforations was evaluated when GMTA and LC GIC were placed against CS or HA matrix.
In this study, GMTA was used instead of white MTA (WMTA) because of its superior properties, i.e., less solubility and dimensional changes  and better antibacterial effect. ,
In this study, perforation width was standardized with the diameter of a # 2 round bur as in previous studies. ,, Depth was an uncontrolled variable dependent on dentin-cementum thickness of each tooth. To control this variable, the percentage of dye penetration in relation to the entire dentin-sealing material interface was calculated.
Methylene blue dye was used to evaluate microleakage because it is a simple and an inexpensive technique and has displayed better penetration results than eosin  or the radioisotope tracers, 45 Ca-labeled calcium chloride, 14 C-labeled urea and 125 I-labeled albumin. ,
In this study, teeth with furcation perforations repaired with MTA alone showed significantly lesser dye leakage than teeth repaired with other materials, i.e., MTA with CS or HA, LC GIC alone and LC GIC with CS or HA.
MTA has inherent superior sealing ability as demonstrated in several studies. ,,,, The superior sealing ability of MTA could be due to its hydrophilic nature, ability to adapt to cavity walls and expand while setting. Pitt Ford et al. reported a success rate of 83% using MTA for repair of furcal perforation. The authors related this high success rate to the good sealing ability of MTA, to a hard-set that provides a solid barrier against which tissue can organize and to the bactericidal effect of the material that results from its high pH.
The present study showed that internal matrix significantly decreased the sealing ability of MTA, which confirmed the results of previous studies. ,, This could be due to the debris of internal matrix remaining on the walls of the perforation. The bonding of MTA to dentin is entirely mechanical. Unset MTA may penetrate into the dentin interface and form mechanical interlocking. The calcium ions released by MTA interact with the tissue fluid to form HA.  As a mixture, matrix material fills voids and therefore does not allow MTA to enter into these voids.
When compared with MTA, LC GIC alone and with internal matrix demonstrated greater dye penetration. The reason could be the polymerization contraction of the material. Chong et al. reported better adaptation of LC GIC to one dentinal wall and gaps in the opposite dentinal wall.
In the current study, LC GIC alone showed significantly lesser leakage than LC GIC with internal matrix. Contrary to these findings, Alhadainy and Abdalla  found that glass ionomer alone showed significantly more leakage than glass ionomer over CS. This conflicting report may be because of the fact that in their study the repairing procedure was done under a stereomicroscope that provided better visibility for removal of CS from dentinal wall during freshening of the wall. In contrast to their study, the present study was done under naked eye to simulate the clinical situation. Therefore, there is possibility of some matrix material clinging to the dentinal wall of the perforation. This might have interfered with chemical bonding and adaptation of LC GIC to the dentinal walls.
On comparing the sealing ability of MTA over matrix with LC GIC over matrix material, i.e., either CS or HA, MTA showed significantly better result than LC GIC. The probable reason can be correlated with the properties and bonding mechanism of the repair materials. The presence of the debris on the perforation walls could have more adversely affected the chemical bonding in LC GIC. MTA, on the other hand, shows mechanical bonding and is hydrophilic, easily adapted to cavity walls and expands while setting.
On comparing the sealing ability of either LC GIC or MTA over different matrix materials, the sealing of both LC GIC and MTA over CS was significantly better than over HA. These findings were not consistent with those of Alhadainy and Abdalla,  who reported that CS when used as barrier showed more dye leakage than HA. However, the difference was not statistically significant. Alhadainy et al. found an average histologic success of 67% for CS and 62% for HA-based material. These barrier materials were used to repair furcal perforations. However, there was no significant difference between them.
The inferior sealing ability of repair materials over HA could be because it is granular, difficult to manipulate, has poor adaptability to the walls and does not set.
Within the constraints of this study, it can be concluded that
- MTA showed significantly less leakage than LC GIC when used with and without an internal matrix;
- Internal matrix significantly reduced the sealing ability f both MTA and LC GIC and
- HA reduced the sealing ability of both MTA and LC GIC to a significantly greater extent than CS.
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Department of Conservative Dentistry & Endodontics, ITS-CDSR, Delhi-Meerut Road, Muradnagar, Ghaziabad, Uttar Pradesh
Source of Support: None, Conflict of Interest: None