© 1990 S. Karger A G . Basel 0008-6568/90/0242-0142 S 2.75/0
Caries Res 1990;24:142-144
Action of Fluoride on Initiation of Early Root Surface Caries in vivo (Short Communication) B. 0gaarda, J. Arendsh, G. Rollac a Department of Orthodontics, Dental Faculty, University of Oslo, Norway; b Materia Technica, Dental School, University of Groningen, The Netherlands; c Department of Pedodontics, and Caries Prophylaxis, Dental Faculty, University of Oslo, Norway
It is well established that fluoride has an inhibiting effect on enamel caries development and progression. The mechanisms behind the cariostatic effect are not fully established, although recent research seems to indicate that the formation of material like calcium fluoride may be important [0gaard, 1990]. Less infor mation is available on the effect of fluoride on initi ation and progression of root caries. The purpose of the present study was, therefore, to investigate the car ies-inhibiting effect of fluoride rinsing on the initi ation of root surface caries. Slabs were cut from the buccal part of roots of freshly extracted premolars. The slabs were cut from the part adjacent to the cemento-enamel junction. Re maining organic tissue fragments on the cementum were removed by careful currettage as described by Saxegaard et al. [1987], The slabs were mounted in a removable appliance (Hawley retainer) in the upper jaw. The slabs were covered with orthodontic banding material for plaque accumulation as described previ ously [0gaard et al., 1988a], Three slabs were mount ed on each appliance. Five individuals (15 years of age) wore the appliance for 4 weeks. They were re quested to rinse every evening with 10 ml of a neutral 0.2% sodium fluoride solution and use a non-fluoridated toothpaste. The root slabs for microradiogra phy were cut with a water-cooled diamond bur and stored in closed polyethylene tubes on wet cotton at 100% relative humidity at 4°C until analysis to avoid shrinkage [0gaard et al., 1988a],
The root surfaces were analyzed by means of mi croradiography. To determine the mineral content in vol%, microradiographs were made of planoparallel sections (approximately 90 pm thick) together with an aluminium calibration step wedge on high-resolution photographic film (Kodak high-speed holographic film SO-253) using a monochromatic X-ray genera tor (Philips PW 1730) at 20 kV and 15 mA [Arends and ten Bosch, 1986]. The volume percentage of mineral present in the root sections was estimated densitometrically using the formula of Angmar et al. [1963]. The slit dimen sions of the microdensitometer were 6x 73 pm2. The films were moved with respect to the slit at a speed of 2.7 pm s '1. The parameters analyzed were (1) lesion depth (ld in pm) - demineralization distance from the outer surface and (2) total mineral loss (AZ in vol% x pm). Recently it was found that lesion progression and mineral loss are about 2.5 times greater in root sur faces than in human enamel. Whereas the deminerali zation in enamel is roughly linear with time, the root surfaces demineralized very fast during the 1st week and much slower thereafter [0gaard et al., 1988a]. In fact, it was shown that the lesion had passed beyond the cementum-dentine junction already during the 1st week. The results from the present study (table 1) showed that daily rinsing with a neutral fluoride solu tion inhibited both lesion development and mineral loss by 70% when compared to previous data [0gaard
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Key Words. Caries, in vivo • Fluoride, topical ■Root surfaces
143
Table 1. Mineral loss and lesion depth in root surfaces exposed et al., 1988a] involving the same individuals. The to a cariogenic challenge for 4 weeks in a fluoride rinsing group mean lesion depth in the fluoride-rinsing group was and a group without rinsing 56 urn. By assuming the thickness of the cementum to be about 20-50 um, it appears that the fluoride proce Procedure Lesion Mineral Experimental dure has inhibited the lesion from penetrating deep depth period loss Z pm vol% • pm weeks into the dentin. In vitro data also showed that fluoride has an inhibiting effect on lesion development in den 56119 4 853 ± 191 tin, although higher concentrations were needed com Rinsing (0.2% NaF) 4,010 ±600 263 ± 20 4 No rinsing“ pared with enamel [Arends et al., 1987], It is interest ing to note that the same percentage reduction in The same individuals (n • 5) in both groups. mineral loss was found for enamel after daily fluoride a From Ogaard et al. [1988a]. rinsing [0gaard et al., 1986]. One explanation for this could be that the plaque formed in the model is simi lar, no matter what hard tissue is present, and that the reduction in lesion formation is due to bacterial inhi bition underneath the band. However, such an effect tissues [Hals and Selvig, 1977], lesion formation in ce has been found to be temporary in banding models mentum is very rapid in the absence of a fluoride [Arneberg et al., 1985], It appears, therefore, that the treatment [Ogaard et al., 1988a]. The observation of main effect of fluoride in this model is on the dental the present study that topical fluoride in the form of daily mouthrinsing inhibited lesion development in hard tissues. In vitro experiments have shown that material like root surfaces may support the hypothesis that the flu calcium fluoride in the form of spherical globules can oride in the liquid phase is more important than a be observed both on dentin and cementum after topi high content of firmly bound fluoride [Fejerskov et cal fluoride treatment. More fluoride was deposited al., 1981; Ogaard etal., 1988b]. on dentin and cementum than on enamel from a neu tral 2% NaF solution [Saxegaard et al., 1987]. It has recently been suggested that material like calcium References fluoride may act as a depot of fluoride to be released during cariogenic challenges. The stability of material Angmar B, Carlstrom D, Glas JE: Studies on the ultrastructure of similar to calcium fluoride in the oral environment dental enamel. J Ultrastruct Res 1963;8:12-23. has been found to be higher than previously esti Arends J, ten Bosch JJ: In vivo de- and remineralization of dental enamel; in Leach SA (ed): Factors Relating to Demineralisation mated. This is probably due to adsorption of phos and Remineralisation of Teeth. Oxford, 1RL Press, 1986, phate ions in the form of HPOj and protein molecules pp 1-11. onto the surface of the material like calcium fluoride Arends J, Christoffersen J, Ruben J, Christoffersen MR: Lesion progress in dentine and the role of fluoride; in Thylstrup A, [Rolla and Ogaard, 1986; Lagerlof et al., 1988]. It is Leach SA, Quist V (eds): Dentine and Dentine Reactions in the conceivable that material similar to calcium fluoride Oral Cavity. Oxford, IRL Press, 1987, pp 117-125. deposited in cementum during fluoride rinsing may Arends J, Nelson DGA, Dijkman AG, Jongebloed WL: Effect of account for the cariostatic effect observed in the pres various fluorides on enamel structure and chemistry; in ent study. Guggenheim B (ed): Cariology Today. Basel, Karger, 1984, The mechanisms for the cariostatic effect of topi pp 231-236. cally applied fluoride are not completely known. It Arneberg P, Ogaard B, Scheie AA: Effect of 0.2% NaF rinses upon the selection of Strep, mutars in plaque (abstract 8). J Dent Res has been suggested that the particles like calcium fluo 1985;64:756. ride may form a diffusion barrier to acids [ten Cate ten Cate JM, Duijsters PPE: Alternating demineralization and re and Duijsters, 1982] and/or that fluoride ions are re mineralization of artificial enamel lesions. Caries Res 1982; 16: 201 - 210 . leased from this material to the liquid phase. The in creased fluoride in the liquid may adsorb onto the Fejerskov O, Thylstrup A, Larsen MJ: Rational use of fluorides in caries prevention. A concept based on the possible cariostatic enamel mineral and thereby inhibit the rate of disso mechanisms. Acta Odontol Scand 1981;39:241-249. lution [Arends et al., 1984]. Hals E, Selvig K A: Correlated electron probe microanalysis and mi Despite the fact that cementum contains a higher croradiography of carious and normal dental cementum. Caries concentration of fluoride than any other mineralized Res 1977;11:62-75.
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Action of F on Root Surface Caries
144
Saxegaard E, Valderhaug J, Rolla G: Deposition of fluoride on dentin and cementum after topical application of 2% NaF; in Thylstrup A, Leach SA, Qvist V (eds): Dentine and Dentined Reactions in the Oral Cavity. Oxford, IRL Press, 1987, pp 199-206.
Submitted: November2I, 1988 Accepted: October 30, 1989 Dr. Bjorn Ogaard Department of Orthodontics Dental Faculty University of Oslo POBox 1109, Blindern N -0317 Oslo 3 (Norway)
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Lagerlöf F, Saxegaard E, Barkvoll P, Rolla G: Effects of inorganic orthophosphate and pyrophosphate on dissolution of calcium fluoride in water. J Dent Res 1988;67:447-449. 0gaard B: Effects of fluorides on caries development and progres sion in vivo. Fluorides: Mechanisms of action and recommen dations for use. J Dent Res, 1990, in press. 0gaard B, Arends J, Schuthof J, et al: Action of fluoride on initia tion of early enamel caries in vivo. Caries Res 1986;20:270-277. 0gaard B, Rolla G, Arends J: In vivo progress of enamel and root surface lesions under plaque as a function of time. Caries Res 1988a;22:302-305. 0gaard B, Rolla G, Ruben J, Dijkman T, Arends J: Microradiographic study of demineralization of shark enamel in a human caries model. Scand J Dent Res 1988b;96:209-211. Rolla G, 0gaard B: Studies on the solubility of calcium fluoride in human saliva; in Leach SA (ed): Factors Relating to Demineral isation and Remineralisation of Teeth. Oxford, IRL Press, 1986, pp 45-50.
0gaard/Arends/ Rolla
Caries Res 1990;24:142-144
Action of Fluoride on Initiation of Early Root Surface Caries in vivo (Short Communication) B. 0gaarda, J. Arendsh, G. Rollac a Department of Orthodontics, Dental Faculty, University of Oslo, Norway; b Materia Technica, Dental School, University of Groningen, The Netherlands; c Department of Pedodontics, and Caries Prophylaxis, Dental Faculty, University of Oslo, Norway
It is well established that fluoride has an inhibiting effect on enamel caries development and progression. The mechanisms behind the cariostatic effect are not fully established, although recent research seems to indicate that the formation of material like calcium fluoride may be important [0gaard, 1990]. Less infor mation is available on the effect of fluoride on initi ation and progression of root caries. The purpose of the present study was, therefore, to investigate the car ies-inhibiting effect of fluoride rinsing on the initi ation of root surface caries. Slabs were cut from the buccal part of roots of freshly extracted premolars. The slabs were cut from the part adjacent to the cemento-enamel junction. Re maining organic tissue fragments on the cementum were removed by careful currettage as described by Saxegaard et al. [1987], The slabs were mounted in a removable appliance (Hawley retainer) in the upper jaw. The slabs were covered with orthodontic banding material for plaque accumulation as described previ ously [0gaard et al., 1988a], Three slabs were mount ed on each appliance. Five individuals (15 years of age) wore the appliance for 4 weeks. They were re quested to rinse every evening with 10 ml of a neutral 0.2% sodium fluoride solution and use a non-fluoridated toothpaste. The root slabs for microradiogra phy were cut with a water-cooled diamond bur and stored in closed polyethylene tubes on wet cotton at 100% relative humidity at 4°C until analysis to avoid shrinkage [0gaard et al., 1988a],
The root surfaces were analyzed by means of mi croradiography. To determine the mineral content in vol%, microradiographs were made of planoparallel sections (approximately 90 pm thick) together with an aluminium calibration step wedge on high-resolution photographic film (Kodak high-speed holographic film SO-253) using a monochromatic X-ray genera tor (Philips PW 1730) at 20 kV and 15 mA [Arends and ten Bosch, 1986]. The volume percentage of mineral present in the root sections was estimated densitometrically using the formula of Angmar et al. [1963]. The slit dimen sions of the microdensitometer were 6x 73 pm2. The films were moved with respect to the slit at a speed of 2.7 pm s '1. The parameters analyzed were (1) lesion depth (ld in pm) - demineralization distance from the outer surface and (2) total mineral loss (AZ in vol% x pm). Recently it was found that lesion progression and mineral loss are about 2.5 times greater in root sur faces than in human enamel. Whereas the deminerali zation in enamel is roughly linear with time, the root surfaces demineralized very fast during the 1st week and much slower thereafter [0gaard et al., 1988a]. In fact, it was shown that the lesion had passed beyond the cementum-dentine junction already during the 1st week. The results from the present study (table 1) showed that daily rinsing with a neutral fluoride solu tion inhibited both lesion development and mineral loss by 70% when compared to previous data [0gaard
Downloaded by: Univ. of California Santa Barbara 128.111.121.42 - 3/27/2018 5:01:29 PM
Key Words. Caries, in vivo • Fluoride, topical ■Root surfaces
143
Table 1. Mineral loss and lesion depth in root surfaces exposed et al., 1988a] involving the same individuals. The to a cariogenic challenge for 4 weeks in a fluoride rinsing group mean lesion depth in the fluoride-rinsing group was and a group without rinsing 56 urn. By assuming the thickness of the cementum to be about 20-50 um, it appears that the fluoride proce Procedure Lesion Mineral Experimental dure has inhibited the lesion from penetrating deep depth period loss Z pm vol% • pm weeks into the dentin. In vitro data also showed that fluoride has an inhibiting effect on lesion development in den 56119 4 853 ± 191 tin, although higher concentrations were needed com Rinsing (0.2% NaF) 4,010 ±600 263 ± 20 4 No rinsing“ pared with enamel [Arends et al., 1987], It is interest ing to note that the same percentage reduction in The same individuals (n • 5) in both groups. mineral loss was found for enamel after daily fluoride a From Ogaard et al. [1988a]. rinsing [0gaard et al., 1986]. One explanation for this could be that the plaque formed in the model is simi lar, no matter what hard tissue is present, and that the reduction in lesion formation is due to bacterial inhi bition underneath the band. However, such an effect tissues [Hals and Selvig, 1977], lesion formation in ce has been found to be temporary in banding models mentum is very rapid in the absence of a fluoride [Arneberg et al., 1985], It appears, therefore, that the treatment [Ogaard et al., 1988a]. The observation of main effect of fluoride in this model is on the dental the present study that topical fluoride in the form of daily mouthrinsing inhibited lesion development in hard tissues. In vitro experiments have shown that material like root surfaces may support the hypothesis that the flu calcium fluoride in the form of spherical globules can oride in the liquid phase is more important than a be observed both on dentin and cementum after topi high content of firmly bound fluoride [Fejerskov et cal fluoride treatment. More fluoride was deposited al., 1981; Ogaard etal., 1988b]. on dentin and cementum than on enamel from a neu tral 2% NaF solution [Saxegaard et al., 1987]. It has recently been suggested that material like calcium References fluoride may act as a depot of fluoride to be released during cariogenic challenges. The stability of material Angmar B, Carlstrom D, Glas JE: Studies on the ultrastructure of similar to calcium fluoride in the oral environment dental enamel. J Ultrastruct Res 1963;8:12-23. has been found to be higher than previously esti Arends J, ten Bosch JJ: In vivo de- and remineralization of dental enamel; in Leach SA (ed): Factors Relating to Demineralisation mated. This is probably due to adsorption of phos and Remineralisation of Teeth. Oxford, 1RL Press, 1986, phate ions in the form of HPOj and protein molecules pp 1-11. onto the surface of the material like calcium fluoride Arends J, Christoffersen J, Ruben J, Christoffersen MR: Lesion progress in dentine and the role of fluoride; in Thylstrup A, [Rolla and Ogaard, 1986; Lagerlof et al., 1988]. It is Leach SA, Quist V (eds): Dentine and Dentine Reactions in the conceivable that material similar to calcium fluoride Oral Cavity. Oxford, IRL Press, 1987, pp 117-125. deposited in cementum during fluoride rinsing may Arends J, Nelson DGA, Dijkman AG, Jongebloed WL: Effect of account for the cariostatic effect observed in the pres various fluorides on enamel structure and chemistry; in ent study. Guggenheim B (ed): Cariology Today. Basel, Karger, 1984, The mechanisms for the cariostatic effect of topi pp 231-236. cally applied fluoride are not completely known. It Arneberg P, Ogaard B, Scheie AA: Effect of 0.2% NaF rinses upon the selection of Strep, mutars in plaque (abstract 8). J Dent Res has been suggested that the particles like calcium fluo 1985;64:756. ride may form a diffusion barrier to acids [ten Cate ten Cate JM, Duijsters PPE: Alternating demineralization and re and Duijsters, 1982] and/or that fluoride ions are re mineralization of artificial enamel lesions. Caries Res 1982; 16: 201 - 210 . leased from this material to the liquid phase. The in creased fluoride in the liquid may adsorb onto the Fejerskov O, Thylstrup A, Larsen MJ: Rational use of fluorides in caries prevention. A concept based on the possible cariostatic enamel mineral and thereby inhibit the rate of disso mechanisms. Acta Odontol Scand 1981;39:241-249. lution [Arends et al., 1984]. Hals E, Selvig K A: Correlated electron probe microanalysis and mi Despite the fact that cementum contains a higher croradiography of carious and normal dental cementum. Caries concentration of fluoride than any other mineralized Res 1977;11:62-75.
Downloaded by: Univ. of California Santa Barbara 128.111.121.42 - 3/27/2018 5:01:29 PM
Action of F on Root Surface Caries
144
Saxegaard E, Valderhaug J, Rolla G: Deposition of fluoride on dentin and cementum after topical application of 2% NaF; in Thylstrup A, Leach SA, Qvist V (eds): Dentine and Dentined Reactions in the Oral Cavity. Oxford, IRL Press, 1987, pp 199-206.
Submitted: November2I, 1988 Accepted: October 30, 1989 Dr. Bjorn Ogaard Department of Orthodontics Dental Faculty University of Oslo POBox 1109, Blindern N -0317 Oslo 3 (Norway)
Downloaded by: Univ. of California Santa Barbara 128.111.121.42 - 3/27/2018 5:01:29 PM
Lagerlöf F, Saxegaard E, Barkvoll P, Rolla G: Effects of inorganic orthophosphate and pyrophosphate on dissolution of calcium fluoride in water. J Dent Res 1988;67:447-449. 0gaard B: Effects of fluorides on caries development and progres sion in vivo. Fluorides: Mechanisms of action and recommen dations for use. J Dent Res, 1990, in press. 0gaard B, Arends J, Schuthof J, et al: Action of fluoride on initia tion of early enamel caries in vivo. Caries Res 1986;20:270-277. 0gaard B, Rolla G, Arends J: In vivo progress of enamel and root surface lesions under plaque as a function of time. Caries Res 1988a;22:302-305. 0gaard B, Rolla G, Ruben J, Dijkman T, Arends J: Microradiographic study of demineralization of shark enamel in a human caries model. Scand J Dent Res 1988b;96:209-211. Rolla G, 0gaard B: Studies on the solubility of calcium fluoride in human saliva; in Leach SA (ed): Factors Relating to Demineral isation and Remineralisation of Teeth. Oxford, IRL Press, 1986, pp 45-50.
0gaard/Arends/ Rolla
