Using a Fluoride Releasing Resin to Reduce Cervicae Sensitivity

USING A FLUORIDE-RELEASING RESIN IO REDUCE CERVICAE SENSITIVITY MARV TAVARES, RAUL F. DEPAOLA, D.D.S., M.S.D., M.S. HYG.; RRAMOD SOPARKAR, B.D.S., D.M.D., M.S.

© ensitivity of exposed root surfaces is a common dental complaint. M arket survey data projections indicate th a t nearly 40 million adults in the United States are affected at one time or another by tooth hypersen­ sitivity, and th a t 10 million of these may be chronically affected.1 Studies indicate th a t more than 90 percent of sensitive sites are at the cervical m ar­ gins.2,3Whether hypersensitivity results from gradual gingival recession and subsequent dentin exposure or is caused by gingival surgical procedures, the clinician is faced with resolving the patient’s pain. Currently, the hydrodynamic theory is the most widely accepted hypothesis as to what causes sensitive teeth. This theory reasons th at fluids move within the dentin in response to external stimuli causing pain.4 For patients with hypersen­ sitive root surfaces, the stimuli may be thermal, mechanical, chemical, bacterial or any combination of these.5 There is strong evidence th a t transm ission of pain-producing stimuli is facilitated by widened outer apertures of the dentinal tubules.6Absi and colleagues demonstrated th a t areas of hypersensitive dentin have open dentinal tubules th a t are

S ig n if ic a n t r e s e a r c h in d ic a t e s th a t d e n ta l h y p e r s e n s itiv ity is c a u s e d b y o p e n d e n tin a l tu b u le s . A r e v ie w o f s u c h r e s e a r c h is p r e s e n t e d a s w e ll a s r e s u lts o f a s tu d y u s in g flu o r id e re s in in a c o m p o s it e re s to ra tio n to r e d u c e s e n s itiv ity .

patent throughout their length, while exposed but non-sensitive dentin areas are characterized by tubules th a t have become occluded.7 Dentin sensitivity is reduced or eliminated when the tubules are blocked. This blockage can occur naturally, albeit slowly, when irregular, atubular dentin forms at the pulpal wall or when mineral deposits from the saliva seal the open tubules.8 Pashley suggested th a t dentinal tubules could be clinically occluded to decrease sensitivity.9Most currently accepted therapies for hypersensitivity either occlude or seal the tubules. Fluorides may accelerate the n atural tubule occlusion as indicated by granular precipita­ tions within dentinal tubules after topical fluoride appli­ cation.1011 However, the desen­ sitizing effects of topical

fluorides tend to be short­ lived.12The widely used topical applications are not sufficiently effective for some patients. Adhesive dental m aterials have been used to seal dentinal tubules, blocking transm ission of pain-producing stimuli to the pulp. One study showed an immediate decrease in sensitivity to hot and cold in 100 percent of teeth sealed with self-polymerizing and ultraviolet polymerizing enamel adhesive resins.13 Twenty-eight days later, the num ber of teeth with decreased sensitivity had dropped to 60 percent. Brannstrom and colleagues eliminated sensitivity by impregnating the dental tubules with resin after acid etching and prolonged drying to create space for the resin tags within the tubules. Before hardening, the surface resin was removed, leaving the resin tags within the tubules. Most of the treated surfaces remained free of symptoms for two to 12 months.8 In a recent study, Yoshiyama and colleagues demonstrated resin penetration of more than 5 microns into dentinal tubules.14 Six months after treatm ent, resin remained in the tubules of asymptomatic teeth, while most of the tubules were open in the hypersensitive teeth. JADA, Vol. 125, October 1994

1337

RESEARCH TABLE 1

To find a m aterial with dentin adhesive TREATMENT CONTROL qualities RANK TEST N MEAN MEAN A*-VALUE T-C th a t did not B a s e lin e require P re -T X 29 1 .6 2 1 .5 9 0 .0 3 .7 3 5 tooth prepa­ P o s t T X 2 9 0.00 1 .5 9 - 1 .5 9 .O O O l ration for 3 m o n th s 0 .1 4 1 .0 7 29 - 0 .9 3 .O O O l retention, 6 m o n t h s 2 9 0 . 2 8 1 .2 1 - 0 .9 3 .O O O l Javid and 12 m o n th s 29 0 .1 7 .O O O l 1 .1 4 - 0 .9 7 his co­ workers * Composite + fluoride-releasing resin. evaluated a single application of isobutyl cyanoa­ amounts of firmly bound root surfaces. Each subject in crylate.15While this provided fluoride. In an in vivo study of the abrasion group (Group A) immediate desensitization, this material, Capilouto and co­ had two teeth with: symptoms gradually returned workers demonstrated fluoride an exposed buccal root sur­ within six weeks as the uptake in the outermost enamel face of 2 millimeters or more; m aterial was lost. Another as well as in deeper layers. ■■ abrasion or erosion on the study evaluated the recently They suggested th at this exposed root surface; developed dentin-bonding m aterial could be used in root•" no restorations or caries on resins under composite restora­ surface restorations.19 the exposed root surface; tions on unprepared teeth.16 The anti-cariogenic effect of ■■ sensitivity to a standardized These researchers found a fluoride enhances the argument cold stimulus. retention rate of 100 percent at for its use in m aterials applied Each subject served as his or six months and 90 percent a t 12 to root surfaces. An anecdotal her own control. In every case, months as well as a marked observation from the root sur­ we selected two teeth th a t were decrease in the percentage of face caries center at Forsyth equally sensitive to cold and sensitive teeth when the Dental Center suggests th at met the inclusion criteria listed; enamel margin was acid etched. hypersensitivity, perhaps then these teeth were randomly It is apparent from all of these because it deters proper oral assigned to receive the resin studies th a t the success of hygiene, was often a precursor application or to serve as un­ reducing root-surface hyper­ to root caries development (P.F. treated controls. Individuals in sensitivity with dentin sealants DePaola, D.D.S., personal Group A received a clear fluor­ is related to retention of the communication, 1992). ide resin application plus a m aterial on the tooth.17 This study investigates the composite restoration placed on The concept of a material efficacy of a slow-release boron the tooth selected for treatm ent. trifluoride BIS-GMA resin in th a t combines the tubuleThe inclusion criteria for occluding potential of fluoride reducing cervical hypersensi­ individuals with non-abraded with the sealant effect of resin tivity on teeth with exposed teeth (Group B) were identical is particularly compelling. buccal root surfaces. except th a t the exposed buccal Brannstrom noted that pro­ root surface had to be non­ METHODS longed fluoride exposure, such as abraded. A slightly thicker th a t from a fluoride-containing Adult subjects were recruited formulation of the clear unfilled resin, might accelerate tubule for this study by newspaper fluoride resin without the obliteration.8Along these lines, notices. There were two groups additional composite restoration Gron and colleagues tested the of subjects with sensitive teeth: was applied to teeth in this efficacy of a slow-release boron those with abraded surfaces group. trifluoride resin material.18 th a t could benefit from Standard application They reported in vitro enamel composite to restore normal procedures for a light cured depositions of substantial contour and those with intact BIS-GMA resin were followed.

SENSITIVITY TO COLO: MEAN SCORES GROUP A.

1338

JADA, Vol. 125, October 1994

RESEARCH

°/o 0.8

H k S C O R E = 1 >m S C O R E = 2

A

B

Baseline

A

B

3 months

A

B

6 m o n th s

A

B 1 2 months

F ig u r e . P e r c e n t o f c o ld - s e n s it iv e t e e th in G r o u p s A a n d B b y s e v e r it y o f s c o r e s ; a t b a s e lin e , th r e e , s ix a n d 1 2 m o n t h s (1 = m o d e r a t e p a in ; 2 = s e v e r e pain).

■» 0 = no significant pain or discomfort; ■■ 1 = moderate, but not severe pain; *■ 2 = severe pain. The Plaque Index and the Gingival Index of Loe and Silness20were used. The pre­ sence and thickness of plaque and debris along the gingival margins of the test teeth were assessed by passing an explorer across the area and were scored on a scale of zero (no plaque) to three (abundant plaque). Gingival status was assessed on the buccal gingiva with scores ranging from zero (no gingivitis) to three (severe gingivitis). Pocket depth was measured at the mid-buccal site of each tooth. These assessm ents were repeated at three, six and 12 months. At these exams, the approximate amount of resin retained on the treated tooth was estim ated by visual and tactile subjective assessm ent by the examiner and scored on the following scale: ■“ 1 = 100 percent to 76 percent retained resin; ■» 2 = 75 percent to 51 percent retained resin; «■*3 = 50 percent to 26 percent retained resin;

At the baseline exam, the After cleaning the treatm ent control and treated teeth in all surface with a non-impregnated subjects were assessed for rubber prophy cup, the enamel therm al (cold) hypersensit­ surface 2 to 3 mm above the ivity, debris, gingival status cemento-enamel junction was and buccal pocket depth. A acid etched with a solution of .005 m illiliter Eppendorf phosphoric acid. A dentin pipette was used to place ice bonding agent (XR Prime, Kerr) w ater, standardized at 0 was applied to the root surface centigrade, on the exposed root for 30 seconds, air dried and surfaces. Subjects were asked light cured for 10 seconds. This to rate th eir response to the was followed by a coat of the w ater on the following scale: fluoride-releasing resin, which was light cured for 30 TABLE 2 seconds. Group A received an additional TREATMENT CONTROL. layer of MEAN MEAN N composite B a s e lin e resin (Kerr 1.69 1.59 P re -T X 29 Herculite, 0.00 1.59 P o st-T X 28 Kerr), which 1.43 0.32 3 m o n th s 28 was light1.25 0.43 28 6 m o n t h s cured, 1.07 0.71 12 m o n th s 28 trimmed and *Fluoride-releasing resin alone. polished.

SENSITIVITY ID COLO: MEAN SCORES GROUP 8.*

T-C

RANK TEST P-VALUE

0 .1 0

.225

-1.59

OOOl

-1.11

OOOl

-0.82

.0004

-0 .3 6

.065

JADA, Vol. 125, October 1994

1339

'RESEARCH TABLE 3

RETENTION OF FLUORIDE-RELEASING RESIN, MEAN SCORES AT 3 ,6 AND 11MONTHS. G R O U P A*

G R O U P

3 m o n th s

1.10

1.93

6 m o n th s

1.14

2.07

12 m o n th s

1.35

2.37

*1= 100%- 76%;

2=75%- 51%;

■■ 4 = 25 percent to 0 percent retained resin. A decision was made a t the outset th a t if resin was lost from a tooth and the tooth returned to the baseline score for the cold stimulus, the resin would be reapplied. This protocol was observed a t the three- and six-month assess­ ments, but not a t the 12-month (final) assessment. D ata from each assessment were analyzed using the Wilcoxon signed rank te st for matched pairs. Results were considered statistically significant if a P-value of less than .05 was obtained. Subjects were advised to con­ tinue their regular dental care and oral hygiene. Some indi­ viduals reported sporadic use of desensitizing toothpastes; this information was recorded, and the participants were not dis­ couraged from using these products. Fifty-eight subjects partici­ pated in the study for more than five months; there were 29 in Group A and 29 in Group B. All of Group A and 28 subjects from Group B completed the study. Resin was reapplied for one Group A subject and three Group B subjects at the threemonth assessment, and four additional Group B subjects at the six-month assessment. No participant required more than one reapplication. 1340

JADA, Vol. 125, October 1994

3=50%- 26%;

B*

4 =25%- 0%.

R ES U LT S

Baseline mean scores for sensitivity to cold were equivalent for the treated and control teeth, ranging from 1.59 to 1.69. Immediately after application of the resin m aterials (post-treatment), the mean scores on the treated teeth dropped to zero, while the control teeth scores stayed the same. The mean scores in Group A rose slightly to 0.14, 0.28 and 0.17 at the three-, sixand 12-month exams, respectively. While there was a general decrease in the control group mean scores (from 1.59 to 1.07 and 1.21 to 1.14), the difference between the treated and control mean scores remained highly significant (P=.0001) at all assessments. In Group B, the mean scores for the treated teeth were higher at three months (0.32), six months (0.43) and 12 months (0.71) than those for Group A. The pattern of decrease in mean control group scores over time was repeated, albeit more gradually, until 12 months, when the mean control group score dropped to 1.07. Again, the improve­ ment in the . Dr. DePaola is head, treated group, Department of as manifested i: C,inical Tria,s> Forsyth Dental by the : Center, Boston.

difference between the treated and control mean scores, was highly significant at three months and six months. At 12 months, because of the combined effect of the increase in treatm ent group mean scores and the decrease in control group scores, there was no longer a statistically significant difference (P = .065). The phenomenon of “improvement” in the control teeth can, perhaps, be attributed to a statistical regression effect to the mean, as well as to a possible placebo effect of treatm ent. At baseline, all teeth in the treatm ent groups scored either 1 or 2 on the therm al sensitivity scale. It is noteworthy that, at baseline, about 20 percent more of the non-abraded teeth (Group B) received a score of 2, indicat­ ing severe pain. At three months, there was the presence of moderate pain in about 10 percent of Group A and 15 percent of Group B. Severe pain was present in 5 percent of Group B. At six months, the number of subjects reporting moderate pain in Group A and Group B increased to almost 25 percent and 40 percent. However, the number of subjects reporting severe pain remained the same. There was little change from six months to 12 months in the moderate

Dr. Tavares is an assistant clinical investigator, Forsyth Dental

Dr. Soparkar is a

Center, 140 The

senior clinical

Fenway, Boston

investigator,

02115. Address

Forsyth Dental

reprint requests to

Center, Boston.

scores. Group A continued to have no subjects reporting severe pain, but this number increased to nearly 20 percent in Group B. At three months, only one subject in Group A had lost any resin, and this was assigned a score of 4. All the other subjects retained 100 percent of their composite resins, resulting in a mean score of 1.10. In Group B, 20 percent of the teeth had lost more than 50 percent of the resin, resulting in a mean of 1.93. At six months, the mean for Group A remained essentially the same at 1.14. In Group B, the mean increased to 2.07, indicating th a t half of the treated teeth had lost nearly 50 percent of their resin material. By the 12-month evaluation, most of the teeth in Group B had lost some resin. With respect to debris, gingi­ val status and pocket depth, the differences between the scores for the treated and control teeth were minor. None of them were statistically significant, suggesting th a t there were no differences in debris or soft tissue between the control and treated teeth in either group. D IS C U S S IO N

This clinical study suggests that a combination of BIS-GMA resin and slow-release fluoride placed over a dentin bonding agent may be therapeutic for sensitive root surfaces th a t do not respond to topical desensit­ izing agents. For individuals with abraded tooth surfaces, placement of the composite and fluoride resin eliminated all sensitivity. At 12 months, virtually all restorations were in place, and the symptoms had vanished. On the non-abraded teeth,

however, the coating of thinner resin had a greater propensity for being dislodged or worn away, as m ight be expected with an unfilled resin. While the return of symptoms ap­ peared to be linked to the loss of resin, there was a discernible lag between resin loss and baseline-level symptom recurrence. At the end of 12 months, nearly all the teeth in Group B had experienced some resin loss. However, as the figure illustrates, fewer than 20 percent of the subjects returned to baseline sensitivity levels. This suggests th a t suppression of symptoms is influenced by additional factors beyond visible coverage of the affected sur­ faces. These factors likely include the resin tags in the dentinal tubules and possibly, the tubule-occluding effects of fluoride. Studies lead by Brannstrom and Yoshiyama demonstrated the effectiveness of resin tags in the relieving hypersensitivity,814 while several investigators have verified the desensitizing, albeit short-lived, effects of topical fluoride.1011 It is not possible with this study design to determine the relative contribution of each potential desensitizing mechanism to the outcome. However, it is highly likely th at tubule coverage and occlusion provided by the resin is primarily responsible for the symptom relief observed. The addition of the slowrelease fluoride agent offers an im portant advantage in th a t it can remain on the tooth surface, providing fluoride ions for deposition and potential remineralization a t the site while also releasing small amounts of fluoride into the

oral environment. The import­ ance of fluoride in caries inhibition and remineralization has been underscored by researchers.2124 In the case of this slow-release boron trifluoride resin, further studies are needed to clarify how it may affect caries experience. C O N C LU SIO N

In this study, fluoride-releasing resin was effective in relieving the symptoms of root surface hypersensitivity. The return of symptoms appeared to be linked to loss of the resin, as indicated by the higher mean sensitivity scores and the greater loss of resin over time in the group th at received thinner resin coverage. On average, the return of baseline-level sensitivity lagged behind the resin loss, indicating th a t the effects of residual resin tags persisted for some time after the resin was no longer clinically apparent. The desensitizing effect, if any, of adding fluoride to the resin could not be determined in this study. There is strong evidence th a t the slow release of intra-oral fluoride can be beneficial for caries inhibition and remineralization. This raises the possibility of bonding an exposed root surface to alleviate hypersensitivity symptoms while simultaneously decreasing its caries susceptibility. To this end, further study is needed of the role of fluoride in this resin, as well as of the optimal resin viscosity with the aim of improving the retention of the material. ■ T his study w as supported by K err Corp. M anufacturing and NIDR G ran t DE-07009. 1. K anapka JA. Over-the-counter dentifrices in th e tre a tm e n t of tooth

JADA, Vol. 125, October 1994

1341

RESEARCH hypersensitivity. D ent Clin N orth Am 1990;34(3):545-60. 2. O rchardson R, Collins WJN. Clinical features of hypersensitive teeth. B r D ent J 1987;162:253-6. 3. G raf H, G alasse R. Morbidity, prevalence, and intrao ral distribution of hypersensitive teeth (A bstract 479). J D ent Res (Special Issue A) 1977;56:A162. 4. B rannstrom M, Astrom A. The hydrodynam ics of the dentine: its possible relationship to dentinal pain. In t D ent J 1972;22(2):219-27. 5. Scherman A, Jacobsen PL. Managing dentin hypersensitivity: w hat treatm ent to recommend to patients. JADA 1992;123(4):57-61. 6. Johnson G, B rannstrom M. The sensitivity of dentin. Changes in relation to conditions a t exposed tubule apertures. Acta Odontol Scand 1974;32:29-38. 7. Absi EG, Addy M, Adam s D. Dentine hypersensitivity. A study of the patency of d entinal tubules in sensitive and non-sensitive cervical dentine. J Clin Periodontol 1987;14:280-4. 8. B rannstrom M, Johnson G, N ordenvall KJ. Transm ission an d control of dentinal pain: resin im pregnation for the desensitization of dentin. JADA 1979;99(10):612-8. 9. Pashley D. D entin perm eability, dentin sensitivity, an d tre a tm e n t through tubule occlusion. J Endod 1986;12:465-74.

10. Hoyt WH, Bibby GG. Use of sodium fluoride for desensitizing dentin. JADA 1943;30(3):1372-6. 11. Ehrlich J, Hochman H, Gedalia I, Tal M. Residual fluoride concentrations and SEM exam ination of root surfaces of hum an teeth after topical application of fluoride in vivo. J D ent Res 1975;54:897-900. 12. Ong G. D esensitizing agents: a review. Clin Prevent D ent 1986;8(3):14-8. 13. Dayton RE, DeMarco TJ, Swedlow D. T reatm ent of hypersensitive root surfaces w ith dental adhesive m aterials. J Perio 1974;45( 12):873-8. 14. Yoshiyama M, Ozaki K, Ebisu S. Morphological characterization of hypersensitive hum an radicular dentin and the effect of a light-curing resin liner on tu b u lar occlusion. Proc F inn D ent Soc 1992;88(Supplement l):337-44. 15. Javid B, B arkhordar RA, Bhinda SV. Cyanoacrylate—a new treatm en t for hypersensitive dentin and cem entum. JADA 1987;114(4):486-8. 16. Ziemiecki TL, Dennison JB , Charbeneau GT. Clinical evaluation of cervical composite resin restorations placed w ithout retention. O per Dent 1987;12:27-33. 17. M artens LC, Surm ont PA. Effect of an ti­ sensitive toothpastes on opened dentinal

tubules an d on two dentin-bonded resins. Clin P revent D ent 1991;13(2):23-8. 18. Gron P, C aslavska V, K ent R, DePaola P. In vitro F deposition in enam el from a coating m aterial (Abstract 165). J D ent Res 1989;68:887. 19. Capilouto ML, DePaola PF, Gron P. In vivo study of slow-release fluoride resin and enam el uptake. Caries Res 1990;24:441-5. 20. Loe H, Silness J. Periodontal disease in pregnancy. I. Prevalence and severity. Acta Odontol Scand 1963;21:533-51. 21. Fejerskov O, T hylstrup A, Larsen MJ. Rational use of fluorides in caries prevention. A concept based on possible cariostatic m echanism s. Acta Odontol Scand 1981;39:241-9. 22. S tra tm an n RG, Donly KJ. Enamel rem ineralization on teeth adjacent to and contacting Class II Glass Ionomer Restorations (Abstract 1709). J D ent Res 1993;72:317. 23. K erber L, Donly KJ. Caries inhibition effects of fluoride-releasing dentinal prim ers (A bstract 1712). J D ent Res 1993;72:317. 24. Shafagih K, Donly KJ. Enamel rem ineralization a t orthodontic bracket m argins cem ented w ith fluoride releasing resin (Abstract 1714). J D ent Res 1993;72:317.

We've made calling for help easier than ever. If you're an employer with employees in the National Guard and Reserve, and you need help, give us a call. We'll answer any questions you may have concerning your responsibilities, as well as your employee's. Or if you simply have a question, we'll help you with that, too. So give us a call at 1-800-336-4590. It's that easy.

¡33R 1342

JADA, Vol. 125, October 1994

EraII C orn e i

A Public Service of This Publication