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The surface features of incipient caries lesions around bonded orthodontic brackets were assessed longitudinally. In standardized periods after debonding and clean-up, color slides were made and silicone impressions were taken of two maxillary incisors on each of six adolescent patients. These teeth were characterized by varying degrees of macroscopically visible demineralized white areas around the bonded brackets. The color slides were studied in a dark room. The positive surface replicas were studied in SEM. At the time of debonding heavy accumulations of dental plaque were observed in all areas corresponding to the white, demineralized areas. During the experimental period there was a reduction in these plaque deposits. The appearance of the lesions changed from chalky-white at the time of debonding to a more diffuse opacity, particularly in the peripheral parts of the lesion. Examination of the surface replicas in the SEM revealed a general tendency toward leveling of the surface of the lesion indicating a loss of porous tissue. At higher magnification the lesions showed signs of wear. Four teeth were presented to illustrate typical examples of the time-related changes at the surface. The present study confirmed that removal of cariogenic challenge results in arrest of further demineralization. The gradual regression of the lesion at the clinical level was believed to be primarily a result of surface abrasion with some redeposition of minerals. [ABSTRACT FROM AUTHOR]

A 6-yr-old Danish girl born and reared in a high fluoride area in Kenya was examined for a period of 1½ yr during which a permanent maxillary central incisor erupted. Present primary and permanent teeth showed obvious dental fluorosis with isolated pits on primary molars. At the time of eruption the crown of the permanent central incisor had its normal anatomical shape. Isolated and confluent pits began to develop about the time of complete eruption. The observations thus confirm previous theories suggesting that pits in fluorosed enamel are secondarily produced defects of traumatic origin. [ABSTRACT FROM AUTHOR]

The present study has examined the relationship between waterborne fluoride, dental fluorosis and skeletal maturity in two Danish areas containing <0.2 and 2.4 parts/106 F- in the drinking water. 12-14-year-old girls, 113 from the non-F- area and 122 from the F- area, born and raised in the areas, were examined. No relationship could be found between skeletal maturity and fluoride content of the drinking water. The association between the severity of dental fluorosis and skeletal maturity in the girls from the area was not statistically significant, but the tendency followed the same pattern as observed in tropical high and low fluoride areas. [ABSTRACT FROM AUTHOR]

The aim of the present study has been to correlate the surface appearance of pitted, fluorosed enamel in the scanning electron microscope (SEM) with the microradiographic features of the underlying tissue. Intact enamel surfaces of severely fluorosed teeth appeared similar to that of normal enamel. In the unabraded surfaces discrete pits were sharply demarcated from the surrounding intact enamel surface leaving steep walls of parallel running rods. The microradiographic appearance of sections made through pits indicated that focal loss of surface enamel occurred corresponding to the inner highly hypomineralized part of the fluorotic subsurface lesion. The abrupt wall formation and the finding that the striae of Retzius never changed direction along the margins of the lesions indicated that pits in fluorosed enamel may be secondarily produced defects rather than true hypoplasias. Further evidence of the posteruptive origin of the defects was derived from the observation that enamel lamellae occasionally formed part of the lateral border. The relatively higher degree of radiopacity observed in the tissue surrounding the pit indicates a posteruptively acquired deposition of minerals in the exposed porous enamel. [ABSTRACT FROM AUTHOR]

Following a single application of a chemically polymer wed fissure sealant (Concise Enamel Bond System®) 60% of the sealants were present after 2 years of examination. The effectiveness of the treatment was highly significant and the caries reduction, irrespective of the sealant status, was found to be about 50%. The caries reduction was 98% in sealed pairs where the material was fully retained. [ABSTRACT FROM AUTHOR]

The aim of the present review has been to give a survey of our present knowledge concerning dental fluorosis and to discuss possible pathogenic mechanisms of this disease. Based on a discussion of the principles behind the Community Index of dental fluorosis it is stressed that absence of harmful community effects should not be confused with a complete absence of fluoride-induced biological changes. The index values apply to communities and they do not equivalate individual diagnosis. Structurally, an increase in fluoride intake results in an increase in degree and extent of porosity of the enamel. Further, dentin changes may be observed. It is stressed dial the clinical and structural features should be kept in mind when possible pathogenic mechanisms of dental fluorosis are discussed. It is obvious that the enamel changes described may not necessarily be a result of a fluoride damage of secretory ameloblast as Commonly assumed. Thus, structural changes similar to those of enamel fluorosis may result from an impairment of the process of enamel maturation. This can either be due to a fluoride-induced change in composition or rheologic features of enamel matrix, or be a result of a disturbance of the cellular processes during enamel maturation. In addition, it is suggested that fluoride may act directly on the poorly understood processes of mineralization in vivo. Finally, results indicate that fluoride interferes with calcium homeostasis, and it cannot be entirely excluded that dental fluorosis may be a result of a more generalized effect of fluoride. It is concluded that much more basic research on fluoride metabolism and formation of mineralized tissues is needed to better understand the effect of fluoride on dental hard tissues. [ABSTRACT FROM AUTHOR]

Enamel structure in human primary incisors was histologically examined in order to compare the observations with those from recent studies on incipient carious and I fluorosed enamel. Ground sections from mandibular incisors of five full-term human infants were examined in polarized light using aqueous media (water, Thoulet's media), alcohols with different refractive indices, and quinoline. Imbibition graphs were made along traverses from the amelodentinal junction (ADJ) to the enamel surface. Quantitative assessments of the birefringence in different media along the traverses indicated a change in the relative volumes of crystallites and surrounding medium with a continuous growth of crystallites toward the ADJ. The influence of organic material is discussed in relation to the differences in calculated form birefringence observed within the specimens. When examined in quinoline, a 30-40-μm-thick surface zone appeared distinct positively birefringent, indicating that the outermost enamel reacted as a molecular sieve. Because of the lower content of minerals the interpretation of this zone differed from that of similar "dark zones" observed in carious and fluorosed enamel. [ABSTRACT FROM AUTHOR]

The purpose of the present investigation was to evaluate the prognosis of primary molars treated with pulpotomy employing formocresol. The material consisted of 98 primary molars. The study included clinical and radiographic observations 3, 12, 24 and 36 months after treatment. The survival rate at the 3-month follow-up was 91 %, whereas the rate was 83 %, 78 % and 70 % -- 12, 24 and 36 months respectively after the treatment. The results were computed according to the life table method. [ABSTRACT FROM AUTHOR]

Using nine serially sectioned germectomized mandibular third molars it was possible to examine light microscopical (LM) and transmission-electron microscopical (TEM) features of maturing human enamel organ cells. The degree of enamel mineralization was estimated by quantitative imbibition studies in polarized light. It was possible to distinguish between three progressive stages of enamel mineralization. The most advanced stage was characterized by external enamel porosity. In the least advanced stages the enamel porosity appeared more extensive beneath a less porous surface layer. Ruffle- and smooth-ended ameloblasts were identified corresponding to the maturing enamel. Smooth-ended ameloblasts were the most frequently observed. However, no preferences for one of the two cell types could be observed in relation to the different stages of enamel mineralization. The maturing human enamel organ cells broadly revealed the same characteristics with respect to morphology features, intracellular organization, and junctional complexes as described in the maturation zone of the rat incisor enamel organ. Our findings therefore add to the view that the basic pattern of amelogenesis is identical in human and rat incisor enamel. [ABSTRACT FROM AUTHOR]

A method is described by means of which organic content in Fissure areas of 12 unerupted 3rd mandibular molars can be prepared for studies in the light microscope (LM) and in tile transmission electron microscope (TEM). Thus, LM and TEM examinations revealed that the organic content throughout the fissure in bone-covered and in mucosa-covered 3rd molars with uncompleted root formation consists of cells belonging to the enamel organ in late or in postmaturative stages. In mucosa-covered teeth with completed root formation it was only possible in identify enamel organ cells at the entrance of the fissure. Deeper parts were occupied by degenerative cells, polymorphonuclear cells and unidentified material. The results indicate that ameloblasts in fissures do not transform to stratified squamous epithelium but gradually degenerate towards terminal stages and remain as such, as the tooth emerges into the oral cavity. [ABSTRACT FROM AUTHOR]

Based on serially cut 200-μm-thick sections from 21 human mandibular third molars, a quantitative characterization was made of the morphology in the mesial and distal interlobal groove. Two parameters were used: depth of interlobal groove and structure angle. The interlobal groove depth varied between 0.13 and 0.55, taken in relation to the maximum crown height. The structure angle varied between 2° and 170°. If the structure angle was ≤ 25°, the interlobal groove was classified as a fissure; if the angle was > 25°, the interlobal groove was classified as a groove. Only in 18% of the sections did the interlobal groove manifest itself as a fissure. The study demonstrates that it was possible unambiguously to describe the two-dimensional profile of interlobal grooves by groove depth and structure angle. [ABSTRACT FROM AUTHOR]

Fifty-two pairs of Class III restorations in a microfilled resin Sitar were inserted in acid-etched cavities. A bevel preparation was performed along the margin of one cavity (A) whereas the other cavity was treated with the surface-active comonomer NPG-GMA before filling (B). After finishing of the restorations, the surface of the type B filling was re-etched and covered with a layer of non-composite, low-viscous resin. Following a 2-yr observation period 65 restorations were classified as "good", 33 were "adequate" and 4 were "unsatisfactory" or were replaced during the study period. The only significant difference between type A and type B restorations was marginal discolorations which most frequently were observed along the beveled type A restorations. The occurrence of such failures was increased by marginal deficiencies and occlusion/articulation on the restorations. [ABSTRACT FROM AUTHOR]

This study examines the influence of sagittal occlusion on occlusal plaque formation in permanent first molars (PFM) in 72 7-10-yr-olds before loss of primary second molars. Of a total of 288 PFM, 140 (49%) were sealed and 23 (8%) filled. Occlusal plaque was recorded at two levels of examination: 1) visible plaque on the entire surface and 2) detailed macromorphologic mapping. Enamel caries was recorded after professional tooth cleaning. After 48 h without tooth brushing, plaque examinations were repeated. Stone models were used for 1) identification of interocclusal contact areas and 2) classification of sagittal molar occlusion. The detailed mapping of plaque on unfilled surfaces showed a clear pattern of preferential locations related to the macromorphology of the occlusal surfaces. Active caries was restricted to those anatomic structures where plaque accumulated. 48-h median plaque values on mandibular molars in normal and with one cusp distal occlusion were significantly lower (P < 0.01) compared to surfaces in 1/4, 1/2 and 3/4 distal molar occlusion. Maxillary molars with normal and with 1 cusp distal occlusion had lower median plaque values than other sagittal occlusion categories. In general, however, plaque scores were higher in maxillary teeth because more than 2/3 of these teeth were without occlusal contact in the distal part. Mandibular occlusal surfaces in normal and with one cusp distal occlusion had significantly fewer active lesions than teeth with 1/4, 1/2 and 3/4 cusp distal occlusion [ABSTRACT FROM AUTHOR]

In 1973 and 1984 the caries status of 624 and 394 children, respectively, was recorded in an urban area of northern Tanzania where the water fluoride content was 2.0-3.5 ppm. Although slightly different scoring criteria were used, the data showed very low levels of caries, and little evidence of increases in caries experience over the 10-yr period. The distribution of caries lesions was markedly skewed, such that a minority of individuals accounted for most of the caries. The levels of caries were low by international standards and equivalent to those found in children from low fluoride areas of Tanzania. [ABSTRACT FROM AUTHOR]

The present study was carried out to examine the effect of application of a fluoride vanish (Duraphat) on experimentally produced caries in vivo. After a 4-wk period of cariogenic challenge on homologous pairs of premolars, Duraphat was applied on one of the teeth while the other was extracted and saved as a control. The Duraphat treated teeth remained in a cariogenic environment for a new period of 2 wk prior to extraction. All the control teeth displayed the classical characteristics of active incipient subsurface carious lesions. The Duraphat treated lesions showed an increase in surface porosity relative to their controls while the subsurface porosity was dramatically reduced. When examined in the SEM, the corresponding surface appeared smooth with a leveling out of the original surface irregularities. High power microscopy disclosed, however, a distinct network of intercrystalline spaces. Application of Duraphat prior to reestablishment of cariogenic challenge apparently gives the to a marked redistribution of minerals in active initial carious lesions. [ABSTRACT FROM AUTHOR]

Three groups of 1-month-old rats were kept on water containing 0.2, 56.5 and 113 parts/106 F-, respectively, for a period of 2 months. These groups were set up in order to study the relationship between long-term administration of high doses of waterborne fluoride, plasma values of fluoride and calcium and changes in forming dentin and enamel of the rat incisor. The microradiographic study revealed that increased levels of fluoride caused a delay in mineralization of the enamel. In the 113 parts/106 group the radiolucent areas in the enamel exhibited a distinct periodicity along the tooth, a phenomenon which cannot at present be explained. In the dentin the fluoride interfered with the process of mineralization giving rise to radiolucent and radiopaque banding in the experimental groups. With increasing levels of fluoride in the water supply a significant increase in plasma fluoride was recorded. In contrast the serum calcium values in both experimental groups were reduced to the same extent, which differed significantly from that of the control group. It is concluded that the fluoride doses which are needed to create fluorotic changes in rats may interfere with calcium metabolism and basic mineralization processes. [ABSTRACT FROM AUTHOR]

The intraoral hydrolysis of monofluorophosphate (MFP) was compared in nine subjects with natural teeth and in nine edentulous subjects after a 1-min mouthrinse with a 100 ppm MFP solution. Analyses of total F and F- in whole saliva samples collected up to 15 min after the rinse suggested that apatite catalyzed breakdown of MFP mediated by dental enamel contributes significantly to the intraoral hydrolysis of MFP.

The purpose of the present investigation was to evaluate the prognosis of primary molars treated with pulpotomy employing formocresol. The material consisted of 98 primary molars. The study included clinical and radiographic observations 3, 12, 24 and 36 months after treatment. The survival rate at the 3-month follow-up was 91%, whereas the rate was 83%, 78% and 70% - 12, 24 and 36 months respectively after the treatment. The results were computed according to the life table method.