Qumhtive
mesment
of sealant wear in vivo
Stanley L. Handelman, D.M.D.,* Qhvind Ekman Jensen, Cand. Odont.,** and Comelis H. Pazneijer, D.M.D., M.Sc.D., D.Sc.‘** Eastman
Dental
Center,
Rochester,
N. Y., and Boston
University
w
ear of sealant materials in vivo has been assessed primarily by clinical evaluation of the integrity of the sealant. On reexamination, sealants have been rated as intact, partially lost, and completely lost.‘-” Sealant wear has also been studied by scanning electron microscopy of tooth replicas.4, 5 These investigations have shown that although sealant wear on the cusp inclines was considerable, intact sealant material was still present at the base of the fissures. A major shortcoming of both techniques, which represent two extreme modes of evaluation, is that neither measures sealant loss quantitatively. The purpose of the present study was to develop a reproducible method for the volumetric assessment of in vivo wear of two pit and fissure sealants, Nuva Sealt and an experimental, filled sealant.$
MATERIALS AND METHODS Three premolars and two permanent molars were used to evaluate an in vivo method of sealant wear. Three of the teeth had Nuva-Seal applied to the occlusal surfaces, while two teeth were sealed with an experimental sealant. All sealant applications were performed under a rubber dam. The experimental sealant was formulated from a chemically modified adduct of bisphenol A and glycidyl methacrylate, a polymerizable hydrophilic monomer, and a 50% inorganic filler by weight, /3-eucryptite. Care was taken not to carry any sealant material over the
*Chairman, Department of General Dentistry. **Research Fellow, Department of General Dentistry. ***Associate Professor of Prosthodontics and Assistant Director of Clinical Research Center. j’The L. D. Caulk Co., Milford, Del. SObtained from Dr. Buoncore, Eastman Dental Center, Rochester, N. Y.
M)2’2-3913/78/110531
+ 03$00.30/06
1978 The C. V. Mushy Co.
School
of Graduate
Dentistry,
Boston,
Mass.
height of the cusp inclines. Both sealants were activated by ultraviolet (UV) light for a minimum of 1 minute. The volume of sealant applied to the occlusal surfaces was determined with presealant and immediate postsealant impressions of the same tooth, using the following technique: A whole-arch impression was made in a RimLock* metal tray using Optosilt impression material. The teeth were subsequently cleaned with a cotton pellet soaked in 3% hydrogen peroxide, isolated with cotton rolls and dried with clean, compressed air. Xantopren Blue? impression material was applied inside the original impression, and the tray was reinserted to its original position. Dies were constructed from the impressions using Spurr Low-Viscosity Embedding MediaJ a clear vinyl-epoxy resin. Silver copings were made directly from the immediate postsealant dies employing an electroplating technique. The occlusal surfaces were painted with Hanau Silversol metallizing agent.8 The dies were then submerged in an electrolyte bath with an electrode in contact with the occlusal surface of the die. The electrode was held in place by attaching it to the die, apical to the area of interest, with a drop of sticky wax. The anode consisted of a silver plate measuring approximately 60 X 65 X 3 mm. A direct current of about 30 m/amp was introduced between the two electrodes, and the die was left in the electrolyte bath for about 4 days. The silver copings were subsequently placed in a DuraLaylJ block measuring approximately 25 X 25 mm in width and length and 10 mm in depth. A *The L. D. Caulk Co., Milford, Del. tUnitek Corp., Monrovia, Calif. $Polysciences, Inc., Warrington, Pa. $Hanau Engineering Co., Buffalo, N. Y [[Reliance Dental Mfg. Co., Worth, Ill.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
531
HANDELhUN,
JENSEN, AND PAMEIJER
and bottom. im, Impression material. w, Tooth replica. SC,Silver coping. ab, Acrylic resin block. Fig. 2. Top
Fig. 1. Schematic cross section of apparatus. SC,Silver coping. sp, Coiled spring. ad, Acrylic disc. /j, Fixed jaw plate. mj, Movable jaw. C-clamp was used to deliver a reproducible force on each die and coping (Fig. 1). The clamp was partially embedded in stone to establish a platform to accept the silver coping (SC) in its DuraLay block. A coiled spring (sp) and an acrylic disk (ad) were interposed between the fixed jaw plate G) and the movable jaw (mj). The movable jaw was modified so that it was tapered to a blunt point approximately 1 mm in diameter. The silver coping embedded in the DuraLay block was placed on the acrylic resin disk, and Xantopren Blue impression material was applied inside the coping immediately prior to the placement of the presealant die. The Xantopren Blue impression material was mixed according to the manufacturer’s suggestions. The screw was turned &&wise in contact with the center of the die until the acrylic resin disk was level with the stone. The weight necessary to bring the acrylic resin disk in contact with the stone was determined by loading of the disk to be approximately 4.4 kg (10 pounds). After the impression material had set completely, the excess material was carefully removed with the aid of a scapel. The die was removed, and the remaining impnzssion material was weighed on a
532
semimicro balance* to the nearest ten thousandth of a gram. The specific gravity of Xantopren Blue, as given by the manufacturer, is 1, and this was confirmed in our laboratory. Thus the weight value in grams, obtained on the semimicro balance, equals the volume in cubic centimeters. To test interexaminer reliability, three replicate measurements for each pretreatment die and its corresponding immediate postsealant coping were made by the two examiners, resulting in a total of 30 measurements. by The results were evaluated statistically performing a paired t-test and by calculating the coefficient of variation for each subset of the data. The technique was extended to evaluate the profile of wear by sectioning the silver copings with the postsealant recall dies in place. The sections were made through the central fossa in a buccolingual direction with a Malco saw blade No. 057t mounted in a Gildings-Hamco thin sectioning machine.$ Each half was subsequently photographed on Kodak Professional Plus-X$ 4 X j-inch sheet film with a
*Me&r balance type H16, Mcttler Instrument Corp., Highstown, N. J. j’Mako Saw Company, Inc., Cranston, R. I. $&me0 Machina, Inc., Rochester, h’. Y #Eastman Kodak Company, Rochester. N. Y.
NOVEMBER 1pIB
VOLUME 40
NUMBER
s
IN VIVOSEALANT WEAR
Table I. Total volumes of sealants (in cubic centimeters) applied to occlusal surfaces Examiner Tooth No.”
16 25 35 46 44
Sealant typet F
F U u u
Mean volume
1 (n = 3)
SD (x10
0.0334 0.0131 0.0165 0.0217 0.0157
*According to the FDI numbering system. tF = Filled, experimental sealant; U = Unfilled
*)
Examiner 2 (n = 3) Coefficient of variation (7%)
5.701 1.000 7.906 4.744 7.906
1.707 0.763 4.792 2.186 5.036
0.0323 0.0118 0.0150 0.0203 0.0127
SD (x lo ‘)
7.036 4.743 2.646 10.583 8.944
Coefficient of variatlan (9%)
2.178 4019 0567 5213 7043
sealant (Nuva-Seal).
Calumet* camera, with the cut surfaces parallel to the plane of the film (Fig. 2).
RESULTS AND DISCUSSION The values obtained by examiner 1 were, on the average, 9.5% higher than those obtained by examiner 2 (Table I). The range was 3.3% to 19.1%. The equation that most closely described the relationship between the two sets of data was expressed as Y = 1.041x-0.00248. Student’s t-test performed on the paired sets of data gave a t-value of 4.86, indicating that the difference between the two examiners was statistically significant (i6 < .02). However, there was a very strong overall correlation between the two examiners (r = +0.99). The average coefficient of variation was 3.0% and 3.8% for examiner 1 and examiner 2, respectively, indicating that intraexaminer reliability was secured with the present method. The differences in the measurements obtained by the two examiners were probably due to differences in the pressure applied on each die and coping with the movable jaw of the modified C-clamp. The two examiners probably employed slightly different tactile reference points to determine when to stop turning the screw. Preliminary results from the 7-month examining interval indicated that approximately 50% of the sealant volume had been lost. It has been demonstrated that a single examiner gives consistent results. Therefore this method is sufficiently sensitive to evaluate the wear of abrasion-susceptible dental materials, such as pit and fissure sealants and composite resins. It does not appear that this method is sufficiently sensitive to assessthe clinical wear of metallic restorations. *Cammet Manufacturing
Mean volume
The present method does not replace the many in vitro experimental models used to assess wear resistance of dental materials, which are more accurate in determining the relative wear resistance between different materials. The in vivo technique described here provides an opportunity to evaluate how the abrasion-susceptible dental materials behave clinically. Furthermore, by utilizing superimposed cross-section photographs of dies from different time intervals, the changes in the wear profile with time can be assessed. A 2-year clinical study using this technique is presently in progress. The results from this experiment will appear in a future article. REFERENCES 1. Going, R. E., Haugh, L. D., Grainger, D. A., and Conti, A. J.: Two-year clinical evaluation of a pit and fissure sealant. Part I: Retention and loss of substance. J Am Dent Assoc 92:388, 1976. 2. Hinding, J. H., and Buonocore, M. G.: The effects of varying the application protocol and the retention of pit and fissure sealant: A two-year clinical study. J Am Dent Assoc 89:127, 1974. 3. Rock, W. P.: Fissure sealants. Further resuhs of clinical trials. Br Dent J 136:317, 1974. 4. Davies, N. E., Tranter, T. C., and Whitten, J. K.: Evaluation of fissure sealant durability in viva using an impression technique. J Dent 3:153, 1975. 5. Tranter, T. C., and Douglas, W. H.: Do fissure sealants really work? J Dent Res 55 (Special Issue D):D117, 1976. (Abst No. 45) Repint requeststo: I%. @WIND EKMAH JENSEN EWTMAN DEIWAL CENTER
800 MAIN ST., E. ROCHESTER,
N. Y. 14603
Company, Chicago, Ill.
THEJOURNALOFPROSTHETICDENTKSTRY
533
mesment
of sealant wear in vivo
Stanley L. Handelman, D.M.D.,* Qhvind Ekman Jensen, Cand. Odont.,** and Comelis H. Pazneijer, D.M.D., M.Sc.D., D.Sc.‘** Eastman
Dental
Center,
Rochester,
N. Y., and Boston
University
w
ear of sealant materials in vivo has been assessed primarily by clinical evaluation of the integrity of the sealant. On reexamination, sealants have been rated as intact, partially lost, and completely lost.‘-” Sealant wear has also been studied by scanning electron microscopy of tooth replicas.4, 5 These investigations have shown that although sealant wear on the cusp inclines was considerable, intact sealant material was still present at the base of the fissures. A major shortcoming of both techniques, which represent two extreme modes of evaluation, is that neither measures sealant loss quantitatively. The purpose of the present study was to develop a reproducible method for the volumetric assessment of in vivo wear of two pit and fissure sealants, Nuva Sealt and an experimental, filled sealant.$
MATERIALS AND METHODS Three premolars and two permanent molars were used to evaluate an in vivo method of sealant wear. Three of the teeth had Nuva-Seal applied to the occlusal surfaces, while two teeth were sealed with an experimental sealant. All sealant applications were performed under a rubber dam. The experimental sealant was formulated from a chemically modified adduct of bisphenol A and glycidyl methacrylate, a polymerizable hydrophilic monomer, and a 50% inorganic filler by weight, /3-eucryptite. Care was taken not to carry any sealant material over the
*Chairman, Department of General Dentistry. **Research Fellow, Department of General Dentistry. ***Associate Professor of Prosthodontics and Assistant Director of Clinical Research Center. j’The L. D. Caulk Co., Milford, Del. SObtained from Dr. Buoncore, Eastman Dental Center, Rochester, N. Y.
M)2’2-3913/78/110531
+ 03$00.30/06
1978 The C. V. Mushy Co.
School
of Graduate
Dentistry,
Boston,
Mass.
height of the cusp inclines. Both sealants were activated by ultraviolet (UV) light for a minimum of 1 minute. The volume of sealant applied to the occlusal surfaces was determined with presealant and immediate postsealant impressions of the same tooth, using the following technique: A whole-arch impression was made in a RimLock* metal tray using Optosilt impression material. The teeth were subsequently cleaned with a cotton pellet soaked in 3% hydrogen peroxide, isolated with cotton rolls and dried with clean, compressed air. Xantopren Blue? impression material was applied inside the original impression, and the tray was reinserted to its original position. Dies were constructed from the impressions using Spurr Low-Viscosity Embedding MediaJ a clear vinyl-epoxy resin. Silver copings were made directly from the immediate postsealant dies employing an electroplating technique. The occlusal surfaces were painted with Hanau Silversol metallizing agent.8 The dies were then submerged in an electrolyte bath with an electrode in contact with the occlusal surface of the die. The electrode was held in place by attaching it to the die, apical to the area of interest, with a drop of sticky wax. The anode consisted of a silver plate measuring approximately 60 X 65 X 3 mm. A direct current of about 30 m/amp was introduced between the two electrodes, and the die was left in the electrolyte bath for about 4 days. The silver copings were subsequently placed in a DuraLaylJ block measuring approximately 25 X 25 mm in width and length and 10 mm in depth. A *The L. D. Caulk Co., Milford, Del. tUnitek Corp., Monrovia, Calif. $Polysciences, Inc., Warrington, Pa. $Hanau Engineering Co., Buffalo, N. Y [[Reliance Dental Mfg. Co., Worth, Ill.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
531
HANDELhUN,
JENSEN, AND PAMEIJER
and bottom. im, Impression material. w, Tooth replica. SC,Silver coping. ab, Acrylic resin block. Fig. 2. Top
Fig. 1. Schematic cross section of apparatus. SC,Silver coping. sp, Coiled spring. ad, Acrylic disc. /j, Fixed jaw plate. mj, Movable jaw. C-clamp was used to deliver a reproducible force on each die and coping (Fig. 1). The clamp was partially embedded in stone to establish a platform to accept the silver coping (SC) in its DuraLay block. A coiled spring (sp) and an acrylic disk (ad) were interposed between the fixed jaw plate G) and the movable jaw (mj). The movable jaw was modified so that it was tapered to a blunt point approximately 1 mm in diameter. The silver coping embedded in the DuraLay block was placed on the acrylic resin disk, and Xantopren Blue impression material was applied inside the coping immediately prior to the placement of the presealant die. The Xantopren Blue impression material was mixed according to the manufacturer’s suggestions. The screw was turned &&wise in contact with the center of the die until the acrylic resin disk was level with the stone. The weight necessary to bring the acrylic resin disk in contact with the stone was determined by loading of the disk to be approximately 4.4 kg (10 pounds). After the impression material had set completely, the excess material was carefully removed with the aid of a scapel. The die was removed, and the remaining impnzssion material was weighed on a
532
semimicro balance* to the nearest ten thousandth of a gram. The specific gravity of Xantopren Blue, as given by the manufacturer, is 1, and this was confirmed in our laboratory. Thus the weight value in grams, obtained on the semimicro balance, equals the volume in cubic centimeters. To test interexaminer reliability, three replicate measurements for each pretreatment die and its corresponding immediate postsealant coping were made by the two examiners, resulting in a total of 30 measurements. by The results were evaluated statistically performing a paired t-test and by calculating the coefficient of variation for each subset of the data. The technique was extended to evaluate the profile of wear by sectioning the silver copings with the postsealant recall dies in place. The sections were made through the central fossa in a buccolingual direction with a Malco saw blade No. 057t mounted in a Gildings-Hamco thin sectioning machine.$ Each half was subsequently photographed on Kodak Professional Plus-X$ 4 X j-inch sheet film with a
*Me&r balance type H16, Mcttler Instrument Corp., Highstown, N. J. j’Mako Saw Company, Inc., Cranston, R. I. $&me0 Machina, Inc., Rochester, h’. Y #Eastman Kodak Company, Rochester. N. Y.
NOVEMBER 1pIB
VOLUME 40
NUMBER
s
IN VIVOSEALANT WEAR
Table I. Total volumes of sealants (in cubic centimeters) applied to occlusal surfaces Examiner Tooth No.”
16 25 35 46 44
Sealant typet F
F U u u
Mean volume
1 (n = 3)
SD (x10
0.0334 0.0131 0.0165 0.0217 0.0157
*According to the FDI numbering system. tF = Filled, experimental sealant; U = Unfilled
*)
Examiner 2 (n = 3) Coefficient of variation (7%)
5.701 1.000 7.906 4.744 7.906
1.707 0.763 4.792 2.186 5.036
0.0323 0.0118 0.0150 0.0203 0.0127
SD (x lo ‘)
7.036 4.743 2.646 10.583 8.944
Coefficient of variatlan (9%)
2.178 4019 0567 5213 7043
sealant (Nuva-Seal).
Calumet* camera, with the cut surfaces parallel to the plane of the film (Fig. 2).
RESULTS AND DISCUSSION The values obtained by examiner 1 were, on the average, 9.5% higher than those obtained by examiner 2 (Table I). The range was 3.3% to 19.1%. The equation that most closely described the relationship between the two sets of data was expressed as Y = 1.041x-0.00248. Student’s t-test performed on the paired sets of data gave a t-value of 4.86, indicating that the difference between the two examiners was statistically significant (i6 < .02). However, there was a very strong overall correlation between the two examiners (r = +0.99). The average coefficient of variation was 3.0% and 3.8% for examiner 1 and examiner 2, respectively, indicating that intraexaminer reliability was secured with the present method. The differences in the measurements obtained by the two examiners were probably due to differences in the pressure applied on each die and coping with the movable jaw of the modified C-clamp. The two examiners probably employed slightly different tactile reference points to determine when to stop turning the screw. Preliminary results from the 7-month examining interval indicated that approximately 50% of the sealant volume had been lost. It has been demonstrated that a single examiner gives consistent results. Therefore this method is sufficiently sensitive to evaluate the wear of abrasion-susceptible dental materials, such as pit and fissure sealants and composite resins. It does not appear that this method is sufficiently sensitive to assessthe clinical wear of metallic restorations. *Cammet Manufacturing
Mean volume
The present method does not replace the many in vitro experimental models used to assess wear resistance of dental materials, which are more accurate in determining the relative wear resistance between different materials. The in vivo technique described here provides an opportunity to evaluate how the abrasion-susceptible dental materials behave clinically. Furthermore, by utilizing superimposed cross-section photographs of dies from different time intervals, the changes in the wear profile with time can be assessed. A 2-year clinical study using this technique is presently in progress. The results from this experiment will appear in a future article. REFERENCES 1. Going, R. E., Haugh, L. D., Grainger, D. A., and Conti, A. J.: Two-year clinical evaluation of a pit and fissure sealant. Part I: Retention and loss of substance. J Am Dent Assoc 92:388, 1976. 2. Hinding, J. H., and Buonocore, M. G.: The effects of varying the application protocol and the retention of pit and fissure sealant: A two-year clinical study. J Am Dent Assoc 89:127, 1974. 3. Rock, W. P.: Fissure sealants. Further resuhs of clinical trials. Br Dent J 136:317, 1974. 4. Davies, N. E., Tranter, T. C., and Whitten, J. K.: Evaluation of fissure sealant durability in viva using an impression technique. J Dent 3:153, 1975. 5. Tranter, T. C., and Douglas, W. H.: Do fissure sealants really work? J Dent Res 55 (Special Issue D):D117, 1976. (Abst No. 45) Repint requeststo: I%. @WIND EKMAH JENSEN EWTMAN DEIWAL CENTER
800 MAIN ST., E. ROCHESTER,
N. Y. 14603
Company, Chicago, Ill.
THEJOURNALOFPROSTHETICDENTKSTRY
533
