0099-2399/91/1709-0444/$03.00/0 JOURNAL OF ENDODONTICS Copyright 9 1991 by The American Association of Endodontists
Printed in U.S.A.
VOL. 17, NO. 9, SEPTEMBER1991
In Vitro Evaluation of Four Methods of Sealer Placement Alfred H. Wiemann, DMD, and Lisa R. Wilcox, DDS, MS
M A T E R I A L S AND M E T H O D S
Sealer is required during root canal obturation, although no studies have shown which method of sealer placement provides the best coverage. This study evaluated and compared four methods of sealer placement: file, lentulo spiral, ultrasonic files, and master gutta-percha cone. Forty mandibular incisors were prepared by a step-back technique. AH26 (0.04 ml) was applied to the placement device, the sealer was placed in the canal, and the canal was obturated with lateral condensation of gutta-percha. The specimens were cleared and evaluated for the presence of the sealer in the apical, middle, and coronal thirds of the canal. The results showed no statistically significant differences among the four groups. The greatest variation in sealer coverage was found in the apical level. Sealer coverage in the coronal and middle thirds was nearly identical regardless of sealer placement technique.
All preparations were made on extracted human mandibular incisors which had been stored in a 1% solution ofthymol in water. Specimens selected had no caries, restorations, or any other noticeable defects. Roots of selected teeth were straight with no curvatures greater than 20. degrees in the apical third. These teeth were randomly assigned into four experimental groups. Figure 1 summarizes the experimental design. The sealer used was AH26 (DeTrey, Zurich, Switzerland). This material was mixed according to the specifications of the manufacturer, resulting in a thick consistency. A small amount of carbon black powder was added to give a dark gray-black color.
Preparation Access was made with a high-speed round bur. Working lengths were determined after a # 10 K-Flex file (Kerr Sybron, Romulus, MI) was placed until visible at the apical foramen and 1 mm was subtracted. Canals were prepared by the stepback flare technique with K-Flex files and Gates Glidden burs for proper taper. Irrigation was frequent and copious with 2.5% sodium hypochlorite inserted with a l%-inch 27-gauge needle. The apical preparation was to a size #35 in all teeth, and preparation was deemed complete when the walls were smooth and a fine finger spreader (Kerr Sybron) could be placed easily to within 1 mm of working length.
The main objective of obturation is to create a fluid tight seal over the entire length of the root canal system. Gutta-percha alone will not seal the canal space as it has no adherence to dentin. Thus, a sealer is required to fill the space between the gutta-percha and the canal wall (1, 2). Ideally, a thin layer of sealer should be applied to all canal walls before placement of the core filling material. Many techniques for sealer placement have been described, most recently involving the use of ultrasonics (3, 4). These later studies have examined crosssections of the canals rather than the entire canal and have not used a standardized amount of sealer. The studies have not demonstrated conclusively which method of sealer placement consistently and completely covers dentinal walls. The purpose of this study was to evaluate four methods of sealer placement in prepared root canals of extracted teeth. Specifically evaluated were (a) location of sealer within the canal after obturation with lateral condensation; and (b) the differences in sealer coverage among four sealer placement techniques.
Obturation All teeth were obturated by lateral condensation of guttapercha and AH26 sealer. Four different methods of sealer placement were used: group 1, #35 K-Flex file; group 2, lentulo spiral; group 3, gutta-percha cone; and group 4, ultrasonic file. A single mix of sealer was used for all teeth. A 1ml tuberculin syringe was used to dispense 0.04 ml of sealer with each placement technique. No additional sealer was used. In group 1, the measured amount of sealer was placed on the apical end of the #35 file and was placed into the canal by counterclockwise rotation and with a gentle pumping action. In group 2, a #3 lentulo spiral (Union Broach Co., Long Island, NY) was selected that would not bind in the prepared
444
Evaluation of Sealer Placement
Vol. 17, No. 9, September 1991
canal and that would also reach the prepared working length. After the handpiece was set to enable the lentulo spiral to spin material apically, the 0.04 ml of sealer was placed on the spiral and was placed into the canal and engaged for a total of 5 s. In group 3, with a standardized #35 gutta-percha point (Kerr Sybron), the measured amount of sealer was placed on the apical end of the point and then placed in the canal with a gentle pumping action. In group 4, the Enac ultrasonic unit (Osada, Tokyo, Japan) was used with a #20 tapered file (Endosonic file; Caulk, Milford, DE). Sealer was placed on the apical portion, and the file was placed into the canal to working length and ultrasonically activated for 5 s. In each group, after sealer placement, a standardized #35 gutta-percha point was placed to length, laterally condensed with a fine finger spreader, and accessory cones were added as needed. Excess gutta-percha and sealer were removed to the level of the cementoenamel junction with a heated plugger, intermediate restorative material temporary was placed, and all of the teeth were stored in containers at 100% humidity and 37~ for 5 days to allow for sealer setting.
4O TEETH i m a n d l h u l d r anlerqurl
l 1 l
In~lr tlmpfiTl.(I w , t h .{ep-bo, k ilart, le, h rllqUl' i M I p r , ' p , l l a l l , , n ~ ~,] ap,, ~1 ~lze ,it ~51
5t'aler
preparauon
AH 26 rn,xed w , l h ( hare ~al hi.< k Pla(ed in a ] ( c l u J 3 e r ( u h n sv{in~t"
Sealer plat e m e m t e c h n r q u e 0 04~( sealer placed o n apical )0ram of each p l a c e m e n t d ( . w c t , L
io Endodonfic f i l e
10 L e n l u l o Spllal
10 G u l t a - P e r ( ha
10 Uhrasoni(
s]5 k Fh'x hh" ~pLJr,
W i t h a slow .spPed h a n d p l e r e spun a p w a l N J~ w [ fr,, S ,e, J
~ IS master ~ o n e pla( ed t~, WL w , t h genllP p u m p ~ n ~ ~, . , , n l
u20 ullrasom~ t,[e pla, {'d ~r •L am} a(tlva;er tot 5 , . ,
~r~h ~ ( ' n l l ~ p u m p , n g
J
O h l u r d u o n w H h laler41 ( r l f l d e n s a l l O n IF,n,. a,, ess,,r V , one~ w , , h ~ a d d m n n a l sealer,
[
iS
D r ( ak dr, h i l l , n . ~ d ( learmN N,rrl, a, i d al, ,,h,)l m l ' l h v l ~ah(vlatt'l
[~dlu~rlr,n
1
r,t s ~ a l e t
,S~ereom,(
Specimen Preparation
445
cl,~,,,ag, 9
n~*~ O p e ~
FIG 1. Summary of the experimental design.
All teeth were subjected to decalcification with 5% nitric acid, dehydration in a series of graded alcohols and were then cleared with methyl salicylate. Evaluation
Each tooth was examined with a stereomicroscope on both proximal surfaces for breadth of sealer coverage. Each tooth was placed under the microscope with a millimeter ruler alongside (Fig. 2). Each of three observers independently evaluated the amount of sealer present in the apical 3 ram, from 3 to 6 mm, and from 6 to 9 ram. Each observer was to evaluate each of the three sections in each root as to (A) no sealer present; (B) from 1 to 50% of the viewed section showing sealer, and (C) from 51 to 100% of the viewed section showing sealer. After one side of the root was examined, the tooth was placed on the opposite surface and the three observers duplicated the above procedure. Thus, six recordings were made for each tooth. Statistical analysis by KruskalWallis test was done to evaluate the correlation between the sealer placement techniques and the amount of sealer coverage. Each evaluator judged every tooth without knowledge of what sealer placement technique had been used. If opinion differed among the evaluators, the majority opinion was the result recorded. RESULTS Statistical analysis of data revealed no significant differences among the four methods of sealer placement. Only one section was completely devoid of sealer. Evaluators were in agreement 97% of the time. The greatest variation in sealer coverage was found in the apical level (Fig. 3). Less sealer was present in the apical third when compared with that in the middle and coronal levels. There was a tendency for more sealer coverage in the apical levels after obturation when sealer was placed by using a
i
9 ,'~/
=/'i
FIG 2. A cleared specimen from group 1 (sealer placed with endodontic file). The tooth is divided into thirds. The sealer is colored black and is indicated by black arrow. Gutta-percha is indicated by the white arrow. In apical and coronal region, the sealer coverage is C (_>50%); in the middle region, the sealer coverage is B (
Printed in U.S.A.
VOL. 17, NO. 9, SEPTEMBER1991
In Vitro Evaluation of Four Methods of Sealer Placement Alfred H. Wiemann, DMD, and Lisa R. Wilcox, DDS, MS
M A T E R I A L S AND M E T H O D S
Sealer is required during root canal obturation, although no studies have shown which method of sealer placement provides the best coverage. This study evaluated and compared four methods of sealer placement: file, lentulo spiral, ultrasonic files, and master gutta-percha cone. Forty mandibular incisors were prepared by a step-back technique. AH26 (0.04 ml) was applied to the placement device, the sealer was placed in the canal, and the canal was obturated with lateral condensation of gutta-percha. The specimens were cleared and evaluated for the presence of the sealer in the apical, middle, and coronal thirds of the canal. The results showed no statistically significant differences among the four groups. The greatest variation in sealer coverage was found in the apical level. Sealer coverage in the coronal and middle thirds was nearly identical regardless of sealer placement technique.
All preparations were made on extracted human mandibular incisors which had been stored in a 1% solution ofthymol in water. Specimens selected had no caries, restorations, or any other noticeable defects. Roots of selected teeth were straight with no curvatures greater than 20. degrees in the apical third. These teeth were randomly assigned into four experimental groups. Figure 1 summarizes the experimental design. The sealer used was AH26 (DeTrey, Zurich, Switzerland). This material was mixed according to the specifications of the manufacturer, resulting in a thick consistency. A small amount of carbon black powder was added to give a dark gray-black color.
Preparation Access was made with a high-speed round bur. Working lengths were determined after a # 10 K-Flex file (Kerr Sybron, Romulus, MI) was placed until visible at the apical foramen and 1 mm was subtracted. Canals were prepared by the stepback flare technique with K-Flex files and Gates Glidden burs for proper taper. Irrigation was frequent and copious with 2.5% sodium hypochlorite inserted with a l%-inch 27-gauge needle. The apical preparation was to a size #35 in all teeth, and preparation was deemed complete when the walls were smooth and a fine finger spreader (Kerr Sybron) could be placed easily to within 1 mm of working length.
The main objective of obturation is to create a fluid tight seal over the entire length of the root canal system. Gutta-percha alone will not seal the canal space as it has no adherence to dentin. Thus, a sealer is required to fill the space between the gutta-percha and the canal wall (1, 2). Ideally, a thin layer of sealer should be applied to all canal walls before placement of the core filling material. Many techniques for sealer placement have been described, most recently involving the use of ultrasonics (3, 4). These later studies have examined crosssections of the canals rather than the entire canal and have not used a standardized amount of sealer. The studies have not demonstrated conclusively which method of sealer placement consistently and completely covers dentinal walls. The purpose of this study was to evaluate four methods of sealer placement in prepared root canals of extracted teeth. Specifically evaluated were (a) location of sealer within the canal after obturation with lateral condensation; and (b) the differences in sealer coverage among four sealer placement techniques.
Obturation All teeth were obturated by lateral condensation of guttapercha and AH26 sealer. Four different methods of sealer placement were used: group 1, #35 K-Flex file; group 2, lentulo spiral; group 3, gutta-percha cone; and group 4, ultrasonic file. A single mix of sealer was used for all teeth. A 1ml tuberculin syringe was used to dispense 0.04 ml of sealer with each placement technique. No additional sealer was used. In group 1, the measured amount of sealer was placed on the apical end of the #35 file and was placed into the canal by counterclockwise rotation and with a gentle pumping action. In group 2, a #3 lentulo spiral (Union Broach Co., Long Island, NY) was selected that would not bind in the prepared
444
Evaluation of Sealer Placement
Vol. 17, No. 9, September 1991
canal and that would also reach the prepared working length. After the handpiece was set to enable the lentulo spiral to spin material apically, the 0.04 ml of sealer was placed on the spiral and was placed into the canal and engaged for a total of 5 s. In group 3, with a standardized #35 gutta-percha point (Kerr Sybron), the measured amount of sealer was placed on the apical end of the point and then placed in the canal with a gentle pumping action. In group 4, the Enac ultrasonic unit (Osada, Tokyo, Japan) was used with a #20 tapered file (Endosonic file; Caulk, Milford, DE). Sealer was placed on the apical portion, and the file was placed into the canal to working length and ultrasonically activated for 5 s. In each group, after sealer placement, a standardized #35 gutta-percha point was placed to length, laterally condensed with a fine finger spreader, and accessory cones were added as needed. Excess gutta-percha and sealer were removed to the level of the cementoenamel junction with a heated plugger, intermediate restorative material temporary was placed, and all of the teeth were stored in containers at 100% humidity and 37~ for 5 days to allow for sealer setting.
4O TEETH i m a n d l h u l d r anlerqurl
l 1 l
In~lr tlmpfiTl.(I w , t h .{ep-bo, k ilart, le, h rllqUl' i M I p r , ' p , l l a l l , , n ~ ~,] ap,, ~1 ~lze ,it ~51
5t'aler
preparauon
AH 26 rn,xed w , l h ( hare ~al hi.< k Pla(ed in a ] ( c l u J 3 e r ( u h n sv{in~t"
Sealer plat e m e m t e c h n r q u e 0 04~( sealer placed o n apical )0ram of each p l a c e m e n t d ( . w c t , L
io Endodonfic f i l e
10 L e n l u l o Spllal
10 G u l t a - P e r ( ha
10 Uhrasoni(
s]5 k Fh'x hh" ~pLJr,
W i t h a slow .spPed h a n d p l e r e spun a p w a l N J~ w [ fr,, S ,e, J
~ IS master ~ o n e pla( ed t~, WL w , t h genllP p u m p ~ n ~ ~, . , , n l
u20 ullrasom~ t,[e pla, {'d ~r •L am} a(tlva;er tot 5 , . ,
~r~h ~ ( ' n l l ~ p u m p , n g
J
O h l u r d u o n w H h laler41 ( r l f l d e n s a l l O n IF,n,. a,, ess,,r V , one~ w , , h ~ a d d m n n a l sealer,
[
iS
D r ( ak dr, h i l l , n . ~ d ( learmN N,rrl, a, i d al, ,,h,)l m l ' l h v l ~ah(vlatt'l
[~dlu~rlr,n
1
r,t s ~ a l e t
,S~ereom,(
Specimen Preparation
445
cl,~,,,ag, 9
n~*~ O p e ~
FIG 1. Summary of the experimental design.
All teeth were subjected to decalcification with 5% nitric acid, dehydration in a series of graded alcohols and were then cleared with methyl salicylate. Evaluation
Each tooth was examined with a stereomicroscope on both proximal surfaces for breadth of sealer coverage. Each tooth was placed under the microscope with a millimeter ruler alongside (Fig. 2). Each of three observers independently evaluated the amount of sealer present in the apical 3 ram, from 3 to 6 mm, and from 6 to 9 ram. Each observer was to evaluate each of the three sections in each root as to (A) no sealer present; (B) from 1 to 50% of the viewed section showing sealer, and (C) from 51 to 100% of the viewed section showing sealer. After one side of the root was examined, the tooth was placed on the opposite surface and the three observers duplicated the above procedure. Thus, six recordings were made for each tooth. Statistical analysis by KruskalWallis test was done to evaluate the correlation between the sealer placement techniques and the amount of sealer coverage. Each evaluator judged every tooth without knowledge of what sealer placement technique had been used. If opinion differed among the evaluators, the majority opinion was the result recorded. RESULTS Statistical analysis of data revealed no significant differences among the four methods of sealer placement. Only one section was completely devoid of sealer. Evaluators were in agreement 97% of the time. The greatest variation in sealer coverage was found in the apical level (Fig. 3). Less sealer was present in the apical third when compared with that in the middle and coronal levels. There was a tendency for more sealer coverage in the apical levels after obturation when sealer was placed by using a
i
9 ,'~/
=/'i
FIG 2. A cleared specimen from group 1 (sealer placed with endodontic file). The tooth is divided into thirds. The sealer is colored black and is indicated by black arrow. Gutta-percha is indicated by the white arrow. In apical and coronal region, the sealer coverage is C (_>50%); in the middle region, the sealer coverage is B (
