0099-2399/91/1707-0324/$03.00/0 JOURNAL OF ENDODONTICS Copyright 9 1991 by The American Association of Endodontists
Printed in U.S.A. VOL. 17, NO. 7, JULY 1991
Human Saliva Coronal Microleakage in Obturated Root Canals: An In Vitro Study Mark E. Magura, DDS, MSD, Abdel H. Kafrawy, BDS, MSD, Cecil E. Brown, Jr., DDS, MS, and Carl W. Newton, DDS, MSD
This study assessed salivary penetration through obturated root canals as related to time by using two methods of analysis--histological examination and dye penetrations. A total of 160 human maxillary anterior teeth were instrumented to size 60 Hedstrom file. Ten of the teeth were not obturated; 150 teeth were obturated by lateral condensation of gutta-percha and Roth's root canal sealer. Fifty of these teeth received intermediate restorative material temporaries to a thickness of - 3 mm. All teeth were immersed in 50 ml of whole human saliva and kept at 37~ and 100% humidity. The saliva was changed daily. At 2, 7, 14, 28, and 90 days, 32 teeth were removed from the saliva. Of these, two were unobturated and were examined for bacterial penetration by culturing of the apical one-third. Ten teeth without temporaries were immersed in Pelikan ink for 2 days to demonstrate the extent of salivary penetration. These teeth were decalcified and cleared to allow direct measurement of dye penetration. Decalcified serial 7-um-thick sections were prepared from the remaining 20 teeth, 10 with and 10 without intermediate restorative material temporaries. The sections were stained with hematoxylin and eosin stain and Brown and Hopps stain. Saliva penetration assessed in histological sections was significantly less than was visualized with dye analysis. Salivary penetration at 3 months was significantly greater than at the four earlier study periods. This amount of salivary penetration was considered to be clinically significant. The results strongly suggest retreatment of obturated root canals that have been exposed to the oral cavity for at least 3 months.
bacterial penetration (8) are some of the methods that have been used in the evaluation of the sealing ability ofendodontic fills. The majority of reports concerning obturation focus on apical leakage. Recently, Madison et al. (4), Swanson and Madison (9), and Madison and Wilcox (10) have reported on the seal produced at the cervical extent of the root canal space. They examined coronal leakage in endodontically treated teeth that were exposed to artificial saliva for varying periods. The teeth were then exposed to Pelikan ink for 2 days. They reported 79 to 85% dye penetration after 3 days of exposure to artificial saliva. This was not statistically different from the longest exposure period of 56 days. The purpose of the in vitro study reported here was to evaluate coronal leakage of human saliva in endodontically treated maxillary anterior teeth. Histological examination of salivary penetration of obturated root canals was used to assess coronal leakage. Dye penetration analysis was also done for comparison of the histological results.
M A T E R I A L S AND M E T H O D S The experimental design is summarized in Fig. I.
Preparation of Teeth One hundred sixty extracted, human maxillary anterior teeth were collected from the Indiana University School of Dentistry Department of Oral Surgery and stored in 10% Formalin. No data regarding age, sex, or reason for extraction were available. Teeth with large, gross carious lesions approaching the pulp were excluded to minimize the possibility of preoperative bacterial contamination of the root canals. Teeth were divided into three groups. The control group consisted of 50 teeth with obturated root canals and intact intermediate restorative material (IRM: L. D. Caulk, Milford, DE) restorations used for access closures. An experimental group, composed of 100 teeth, had obturated root canals and no access closure. A third group of 10 instrumented, unobturated teeth and with no access closures was used to demonstrate salivary penetration. Specimens were handled aseptically throughout the study. Each tooth was root planed to remove organic debris and
There is little doubt that an adequately sealed root canal is necessary to obtain consistent, long-lasting endodontic success. Because of its importance, the seal of endodontically treated teeth has been extensively studied. Dyes (1-3), autoradiography (4, 5), electron microscopic analysis (6, 7), and
324
Vol. 17, No. 7, July 1991
Microleakage in Obturated Canals
/
160 teeth root planed and i n s ~ t e d to size 60 Hedstrom file
\
150 teeth obtumted
10 ~
,/ 50 toeth obOJrated intact temporaries Negative Control Group
325
/
~obOJrat~d
IRM temporaries placed, root surface covered with sticky wax, stored in humidor one week X
lID o b ~ l e d ~ have temporaries removed Experimental Group
10 tmobtun~ed teeth temporarics removed Positive Control Group
Stored in Whole Hnmnn Saliva for experimental periods of 2, 7,14, 28, and 90 day.
/ 10 e x p e r i m e n t a l t e e t h Dye onaiysis
At each tlrr~, period 32 teeth are removed
10 experimental teeth (Group A) 10 control teeth (Group B)
Unobturated Teeth cultured root canal
Histological examination with H&E and Brown & Hopps FIG 1. S u m m a r y of the experimental design.
cementum. Roots were examined with a 60-power dissecting microscope and those with fractures were discarded. To maintain uniformity of the root canal length, the crowns of all specimens were cut to obtain a root length between 13 and 15 mm. After crown removal, an access preparation ~8 m m in depth and 3 m m in diameter was made. The contents of the canal were then removed with a large-sized broach. To establish the working length, a #10 K file was placed into the canal until it was seen at the apical foramen. The working length was obtained by subtracting 1 m m from that measurement. The canals were instrumented to size 60. Instrumentation was performed with 2.5% sodium hypochlorite. No more than 10 ml were used per tooth with total NaOCI exposure time not exceeding 10 min. Canals were dried with sterile paper points. Root canal obturation was completed by using lateral condensation of gutta-percha and Roth's root canal sealer (Roth's 801 Elite Grade; Roth Int., Chicago, IL). Standard #60 Hygenic gutta-percha points (Hygenic standard #60 gutta-percha points; Hygenic Co., Akron, OH) served as the master point with medium-fine Mynol gutta-percha (medium-fine accessory gutta-percha points; Block Drug Co., Jersey City, NJ) as the accessory points. A #3 Luks finger spreader was used to laterally condense the accessory points. Initial penetration of the spreader was to 1 mm of the working length, and conden-
TABLE 1. Coronal leakage in millimeters* Leakage in H & E-Stained Sections
Leakage in Cleared Specimens
S t u d y Period
2 Days 1 Wk 2Wk 1 Month 3 Months
Group A (Experimental)
Group B (Controls)
Group C (Experimental)
0.9 __ 0.9 3.1 _+ 3.2 1+1.3 2.1 _+ 2.8 4.9 _+ 3.4
2.4 _+ 2.1 2.9 + 2.3 2.2+1.5 1.7 __ 1.7 6.5 - 2.6
2.4 __ 1.3 2.8 _+ 0.4 3.6+1.0 4.1 _+ 0.6 10.6 _+ 1.4
* Groups A and C had temporary removed; group B had IRM temporary.
TABLE 2. Two-way analysis of variance* Source
df
MS
F
p
Between groups Between times Group by time Residual
2 4 8 126
69.74 147.94 14.4 3.85
18.11 38.42 3.74
Printed in U.S.A. VOL. 17, NO. 7, JULY 1991
Human Saliva Coronal Microleakage in Obturated Root Canals: An In Vitro Study Mark E. Magura, DDS, MSD, Abdel H. Kafrawy, BDS, MSD, Cecil E. Brown, Jr., DDS, MS, and Carl W. Newton, DDS, MSD
This study assessed salivary penetration through obturated root canals as related to time by using two methods of analysis--histological examination and dye penetrations. A total of 160 human maxillary anterior teeth were instrumented to size 60 Hedstrom file. Ten of the teeth were not obturated; 150 teeth were obturated by lateral condensation of gutta-percha and Roth's root canal sealer. Fifty of these teeth received intermediate restorative material temporaries to a thickness of - 3 mm. All teeth were immersed in 50 ml of whole human saliva and kept at 37~ and 100% humidity. The saliva was changed daily. At 2, 7, 14, 28, and 90 days, 32 teeth were removed from the saliva. Of these, two were unobturated and were examined for bacterial penetration by culturing of the apical one-third. Ten teeth without temporaries were immersed in Pelikan ink for 2 days to demonstrate the extent of salivary penetration. These teeth were decalcified and cleared to allow direct measurement of dye penetration. Decalcified serial 7-um-thick sections were prepared from the remaining 20 teeth, 10 with and 10 without intermediate restorative material temporaries. The sections were stained with hematoxylin and eosin stain and Brown and Hopps stain. Saliva penetration assessed in histological sections was significantly less than was visualized with dye analysis. Salivary penetration at 3 months was significantly greater than at the four earlier study periods. This amount of salivary penetration was considered to be clinically significant. The results strongly suggest retreatment of obturated root canals that have been exposed to the oral cavity for at least 3 months.
bacterial penetration (8) are some of the methods that have been used in the evaluation of the sealing ability ofendodontic fills. The majority of reports concerning obturation focus on apical leakage. Recently, Madison et al. (4), Swanson and Madison (9), and Madison and Wilcox (10) have reported on the seal produced at the cervical extent of the root canal space. They examined coronal leakage in endodontically treated teeth that were exposed to artificial saliva for varying periods. The teeth were then exposed to Pelikan ink for 2 days. They reported 79 to 85% dye penetration after 3 days of exposure to artificial saliva. This was not statistically different from the longest exposure period of 56 days. The purpose of the in vitro study reported here was to evaluate coronal leakage of human saliva in endodontically treated maxillary anterior teeth. Histological examination of salivary penetration of obturated root canals was used to assess coronal leakage. Dye penetration analysis was also done for comparison of the histological results.
M A T E R I A L S AND M E T H O D S The experimental design is summarized in Fig. I.
Preparation of Teeth One hundred sixty extracted, human maxillary anterior teeth were collected from the Indiana University School of Dentistry Department of Oral Surgery and stored in 10% Formalin. No data regarding age, sex, or reason for extraction were available. Teeth with large, gross carious lesions approaching the pulp were excluded to minimize the possibility of preoperative bacterial contamination of the root canals. Teeth were divided into three groups. The control group consisted of 50 teeth with obturated root canals and intact intermediate restorative material (IRM: L. D. Caulk, Milford, DE) restorations used for access closures. An experimental group, composed of 100 teeth, had obturated root canals and no access closure. A third group of 10 instrumented, unobturated teeth and with no access closures was used to demonstrate salivary penetration. Specimens were handled aseptically throughout the study. Each tooth was root planed to remove organic debris and
There is little doubt that an adequately sealed root canal is necessary to obtain consistent, long-lasting endodontic success. Because of its importance, the seal of endodontically treated teeth has been extensively studied. Dyes (1-3), autoradiography (4, 5), electron microscopic analysis (6, 7), and
324
Vol. 17, No. 7, July 1991
Microleakage in Obturated Canals
/
160 teeth root planed and i n s ~ t e d to size 60 Hedstrom file
\
150 teeth obtumted
10 ~
,/ 50 toeth obOJrated intact temporaries Negative Control Group
325
/
~obOJrat~d
IRM temporaries placed, root surface covered with sticky wax, stored in humidor one week X
lID o b ~ l e d ~ have temporaries removed Experimental Group
10 tmobtun~ed teeth temporarics removed Positive Control Group
Stored in Whole Hnmnn Saliva for experimental periods of 2, 7,14, 28, and 90 day.
/ 10 e x p e r i m e n t a l t e e t h Dye onaiysis
At each tlrr~, period 32 teeth are removed
10 experimental teeth (Group A) 10 control teeth (Group B)
Unobturated Teeth cultured root canal
Histological examination with H&E and Brown & Hopps FIG 1. S u m m a r y of the experimental design.
cementum. Roots were examined with a 60-power dissecting microscope and those with fractures were discarded. To maintain uniformity of the root canal length, the crowns of all specimens were cut to obtain a root length between 13 and 15 mm. After crown removal, an access preparation ~8 m m in depth and 3 m m in diameter was made. The contents of the canal were then removed with a large-sized broach. To establish the working length, a #10 K file was placed into the canal until it was seen at the apical foramen. The working length was obtained by subtracting 1 m m from that measurement. The canals were instrumented to size 60. Instrumentation was performed with 2.5% sodium hypochlorite. No more than 10 ml were used per tooth with total NaOCI exposure time not exceeding 10 min. Canals were dried with sterile paper points. Root canal obturation was completed by using lateral condensation of gutta-percha and Roth's root canal sealer (Roth's 801 Elite Grade; Roth Int., Chicago, IL). Standard #60 Hygenic gutta-percha points (Hygenic standard #60 gutta-percha points; Hygenic Co., Akron, OH) served as the master point with medium-fine Mynol gutta-percha (medium-fine accessory gutta-percha points; Block Drug Co., Jersey City, NJ) as the accessory points. A #3 Luks finger spreader was used to laterally condense the accessory points. Initial penetration of the spreader was to 1 mm of the working length, and conden-
TABLE 1. Coronal leakage in millimeters* Leakage in H & E-Stained Sections
Leakage in Cleared Specimens
S t u d y Period
2 Days 1 Wk 2Wk 1 Month 3 Months
Group A (Experimental)
Group B (Controls)
Group C (Experimental)
0.9 __ 0.9 3.1 _+ 3.2 1+1.3 2.1 _+ 2.8 4.9 _+ 3.4
2.4 _+ 2.1 2.9 + 2.3 2.2+1.5 1.7 __ 1.7 6.5 - 2.6
2.4 __ 1.3 2.8 _+ 0.4 3.6+1.0 4.1 _+ 0.6 10.6 _+ 1.4
* Groups A and C had temporary removed; group B had IRM temporary.
TABLE 2. Two-way analysis of variance* Source
df
MS
F
p
Between groups Between times Group by time Residual
2 4 8 126
69.74 147.94 14.4 3.85
18.11 38.42 3.74
