Year : 2008 | Volume
: 26 | Issue : 2 | Page : 59--63
The effect of fissure morphology and eruption time on penetration and adaptation of pit and fissure sealants: An SEM study
N Grewal1, R Chopra2,
1 Department of Pedodontia, Government Dental College, Amritsar, India
2 Department of Pedodontia, Karnavati School of Dentistry, Gandhinagar, India
Department of Pedodontics and Preventive Dentistry, Punjab Government Dental College, Amritsar
This study was designed to examine the effect of fissure morphology on penetration and adaptation of fissure sealants and their relationship with the eruption time of tooth.
Materials and Methods: One hundred and fifty extracted molars and premolars were divided into two groups on the basis of their eruption time. The two groups were further divided into five subgroups on the basis of fissure morphology. An scanning electron microscopic analysis of penetration and adaptation of sealant was done.
Observations and Results: V- and U-shaped fissures were found to have the maximum penetration. Penetration was very poor for I- and IK-types of fissures. No significant difference in penetration was found in relation to eruption time. Adaptation of sealant was not affected by any of the factors.
Conclusion: Even the well-applied sealant does not necessarily provide complete obturation of pits and fissures, thus necessitating periodical clinical observation to determine the success or potential failure of the sealant treatment.
|How to cite this article:|
Grewal N, Chopra R. The effect of fissure morphology and eruption time on penetration and adaptation of pit and fissure sealants: An SEM study.J Indian Soc Pedod Prev Dent 2008;26:59-63
|How to cite this URL:|
Grewal N, Chopra R. The effect of fissure morphology and eruption time on penetration and adaptation of pit and fissure sealants: An SEM study. J Indian Soc Pedod Prev Dent [serial online] 2008 [cited 2020 Jul 14 ];26:59-63
Available from: http://www.jisppd.com/text.asp?2008/26/2/59/41617
For more than 30 years, pit and fissure sealants have been recommended for caries prevention, along with good oral hygiene, optimal fluoridation, and healthy dietary habits, To be effective in the prevention of pit and fissure caries, a sealant must truly 'seal,' i.e., it must completely keep out fermentable food substrates.
The prime factor governing the life expectancy of a sealant is its penetration into the fissures and its adaptability to the walls of the fissures. Sealant penetration deep into fissures with the maximum clinically-tolerable amount extending onto the enamel of cuspal inclines is considered key to its successful bonding. The penetration of sealants into pits and fissures depends on their geometric configuration, the presence of material deposits within them, the physical and chemical properties of the enamel, and good clinical technique.  Depending on the size of the orifice and the support offered by the cuspal inclines, a potential weakness may exist in the sealant and its loss would reexpose the fissure. 
Recently erupted teeth have a porous enamel lining and the fissures are rich in cellular and organic debris. Theoretically, this porous zone of enamel bordering the fissures offers a three-dimensional honeycombed structure into which fissure sealants could be locked.  Any procedure must be carried out at the earliest possible time after eruption to make effective preventive use of fissure sealants. 
It would seem to be more rational to apply fissure sealants almost immediately after eruption of the tooth to obtain complete obturation of the fissures. However, there is no information available regarding the extent of obturation obtained when sealants are used in recently erupted teeth.
Nagano  classified occlusal fissures into five types on the basis of fissure morphology: V, U, Y, I, IK types. This study was conducted to evaluate the influence of fissure morphology on the adhesion and penetration of pit and fissure sealants and the correlation of the time of eruption the tooth to penetration and adhesion of the sealant.
Materials and Methods
This study was conducted on extracted premolars and third molars collected from the outpatient department of Exodontia and Oral Surgery, Punjab Govt. Dental College and Hospital, Amritsar.
Criteria for the selection of teeth for this study were:
Teeth free from cariesTeeth free from any morphological defectTeeth with no previously placed restorationTeeth with stained/unstained pits and fissures, with no softness at the base or showing only minimum decalcification
The extracted premolars and molars were examined and stored in phosphate-buffered saline (PBS) at pH 7.2-7.4).
The extracted teeth were divided into two groups: group A included newly erupted teeth with complete recession of pericoronal operculum and with or without open or sticky grooves and fissures; group B included teeth that had been present in the oral cavity for more than 1 year and less than 4 years.
The extracted teeth were cleaned using the finest tip of an ultrasonic scaler, followed by cleaning of the fissures with a bristle brush without the use of any prophylaxis paste. The teeth were washed with water for 15 s and then dried with an air jet for 10 s.
Ultra-Etch (Ultradent) was delivered to the fissure using Blue Micro tip. It was etched for 15 s and the tooth was then rinsed with an air/water spray.
After air-drying, Primadry (Ultradent) was applied and left for 5 s. The area was then dried by air.
A small drop of sealant (UltraSeal XT Plus) was expressed at the end of the Inspiral brush tip and applied to the deepest anatomy of the fissure using a scrubbing motion. Another small drop was expressed and the desired amount was painted on to the area to create the final shape of the sealant. It was then light-cured for 20 seconds.
After sealing of the fissures, the teeth were subjected to buccolingual sectioning. The root portions were cut off and then the crown portion was sectioned buccolingually at the deepest part of fissure, using a slow rotating diamond disc.
The specimens were allowed to dry for 24 h before subjecting them to gold sputtering. For this, the specimens were mounted on aluminum stubs using double-sided adhesive tape; they were mounted in such a way that the area to be studied faced upwards. The mounted surfaces were then coated with a thin layer (25 nm thickness) of pure gold using an ion sputtering unit.
The stubs were then placed in the vacuum chamber of the scanning electron microscope. The accelerating voltage, angle of tilt, and the aperture were adjusted to suit the specimen to optimize the quality of the micrograph. The surface was scanned and observed on the screen under different magnifications [Figure 1],[Figure 2],[Figure 3],[Figure 4],[Figure 5],[Figure 6].
Fissure morphology of the samples was studied first and then the teeth were separated into five subgroups on the basis of fissure anatomy as follows:
The depth of penetration of the sealant was measured in percentage and the mean width of the gaps along the lateral walls was calculated in each subgroup of samples. The results were compiled, tabulated, and subjected to statistical analysis.
Analysis of variance approach
Testing the significance of the difference between group means through the 't' statistic is relatively easy to understand and carry out, but there is an inherent limitation in the approach in the sense that repetitive application leads to comparatively larger extent of uncertainties in the conclusions. In order to overcome this limitation, we used the analysis of variance (ANOVA) approach.
Penetration of sealants : The results of the ANOVA are presented in [Table 1]. As is obvious from the table, the two combinations showed highly significant results. A break-up of variability between combinations into three components [i.e., due to (a) the five shapes, (b) the eruption time, and (c) interaction between eruption time and shapes] revealed that the significant difference in penetration was due to the different shapes of the fissures and was not affected by the time of eruption. Furthermore, the interaction between the shapes and eruption time was nonsignificant, implying thereby that a similar pattern of penetration was present in both the groups.
Mean width of gaps : The results of the ANOVA are presented in [Table 2]. The values were found to be nonsignificant. Thus, adhesion of the sealant to the lateral walls of fissure was independent of both the shapes and the eruption times of the teeth.
Critical difference (CD) values at 1% level of significance:
(a) For comparing means of any two shapes: 10.02
(b) For comparing means of two groups: not computed due to nonsignificance of corresponding F-value
(c) For comparing interaction effects between shapes and eruption time: not computed due to nonsignificance of corresponding F-value
In order to make comparisons between the five shapes, a line diagram was constructed. The means of the levels of factor A were arranged in descending order and analyzed as follows:
This shows that the depth of penetration was comparable in V-shaped and U-shaped fissures; it was found to be better than the penetration in the other shapes.
For I and IK-shaped fissures, the level of penetration was again found to be similar and was poorer than in the other shapes.
For Y-shaped fissures, the depth of penetration was less than that for U and V-types but more than that for I and IK-types.
The penetration of liquids into cracks and crevices is given by the equation of Bikerman  :
1.50 z 2 = ----- · t
z = depth of the crevice
S = width of the crevice
γ = surface tension of the liquid
θ = advancing contact angle of the liquid
η = viscosity
t = time
The penetration of a liquid into a crack depends upon the viscosity of the liquid and the depth and width of the crack. With a viscous sealant, the many small constricted fissures are less likely to be sealed completely than the wider or less branched fissures.
Galil and Gwinnett  examined the histology of fissures and demonstrated that the contents of fissures consist mainly of ameloblasts lining the wall of the fissures, remnants of cells constituting the enamel organs, and red blood cells; they suggested that the contents of such pits and fissures might significantly influence the effectiveness of certain caries prevention procedures.
In the present study, no significant difference in penetration of sealant was found between the two groups. Although studies have suggested better adhesion and penetration of sealant into the porous enamel of recently erupted teeth, the present study clearly indicated that morphology played a more important role in the penetration and adhesion of sealant.
Penetration of the sealant to the base of the fissure occurred more frequently in shallow fissures than in deep fissures.  Shallow fissures are more likely to be thoroughly cleaned and etched than deep fissures. Residual material in the fissure and air entrapment contributed to limiting sealant penetration into deep constricted fissures.
Prophylaxis paste has been found to be present in significant quantities among the materials present in fissure spaces.  It was for this reason that we used abrasive brush without pumice slurry or prophylaxis paste in the present study: so that the fissure was not plugged with any remnants of the prophylaxis material.
An invasive technique  for the placement of sealants has been suggested to overcome the problems of deep constricted fissures. Higher retention rates for sealants have been obtained following the mechanical preparation of the fissure area.  Basically, the invasive technique leads to a change in the morphology of the fissures from I- and IK-shapes to U- or V-shapes.
The geometry of the pits and fissures certainly influence the penetration of sealants. Invasive techniques may serve to provide a geometric configuration conducive to conditioning and sealant penetration, but such an approach seems contrary to the current philosophy of prevention.
|1||Taylor CL, Gwinnett AJ. A study of penetration of sealants into pits and fissures. J Am Dent Assoc 1973;87:1181-8.|
|2||Tillis TS, Stach DJ, Hatch RA, Cross-Poline GN. Occlusal discrepancies after sealant therapy. J Prosthet Dent 1992;68:223-8.|
|3||Thott EK, Folke LE, Sveen OB. A microbiologic study of human fissure plaque. Scan J Dent Res 1974;82:428.|
|4||Crabb HS. Fissures at risk. Br Dent J 1976;140:303-7.|
|5||Nagano T. Relation between the form of pit and fissure and the primary lesion of caries. Dent Abstr 1961;6:426.|
|6||Rodyhouse RH. Prevention of occlusal fissure caries by use of a sealant: A pilot study. ASDC J Dent Child 1968;35:253-62.|
|7||Galil KA, Gwinnett AJ. Histology of fissures in human unerupted teeth. J Dent Res 1975;54:960-4.|
|8||Symons AL, Chu CY, Meyers IA. The effect of fissure morphology and pretreatment of the enamel surface on penetration and adhesion of fissure sealants. J Oral Rehabil 1996;23:791-8.|
|9||Burrow JF, Burrow MF, Makinson OF. Pits and fissures: Relative space contribution in fissures from sealants, prophylaxis pastes and organic remnants. Aust Dent J 2003;48:175-9.|
|10||Craene GP, Martens C, Dermaut R. The invasive pit and fissure sealing technique in pediatric dentistry: An SEM study of a preventive restoration. ASDC J Dent Child 1988;55:34-42.|
|11||Vineet D, Tandon S. Comparative evaluation of marginal integrity of two new fissure sealants using invasive and non-invasive techniques: A SEM study. J Clin Pediatr Dent 2000;24:291-7.|