Potential of desensitizing toothpastes to reduce the hydrogen peroxide diffusion in teeth with cervical lesions.

PURPOSE: To evaluate the occlusive potential of four toothpastes by atomic force microscopy (AFM) before and after bleaching and quantify the hydrogen peroxide (HP) diffusion into the pulp chamber after application of desensitizing toothpastes in teeth with cervical lesions. METHODS: In 52 human extracted premolars, 2-mm deep artificial cervical lesions (ACL) were prepared and rinsed with EDTA for 10 seconds. Then teeth were adapted in a brushing machine and brushed with one of the following toothpastes [Regular toothpaste with no occlusive compounds Colgate Cavity Protection (CP), Oral-B Pro Health (OB), Colgate ProRelief (PR) and Sensodyne Rapid Relief (RR)] under constant loading (250 g; 4.5 cycles/seconds; 3 minutes). In 13 teeth (control group), no artificial cervical lesion was prepared. After that, the teeth were bleached with 35% HP with three 15-minute applications. The HP diffusion was measured spectrophotometrically as a stable red product based on HP reaction with 4-aminoanthipyrine and phenol in presence of peroxidase, at a wavelength of 510 nm and the dentin surfaces of ACL were evaluated before and after bleaching by AFM. Data was statistically analyzed by one-way ANOVA and Tukey's test (alpha = 0.05). RESULTS: In the AFM images, some modifications of the dentin surface were observed after application of OB and RR. However, only for RR the formation of a surface deposit was produced, which occluded the majority of the dentin tubules. Also, only for RR, this deposit was not modified/removed by bleaching. Despite this, all groups with ACL showed higher HP penetration than sound teeth, regardless of the toothpaste used (P < 0.001).

Therapeutic effects of systemic vitamin k2 and vitamin d3 on gingival inflammation and alveolar bone in rats with experimentally induced periodontitis.

BACKGROUND: The synergistic effects of vitamin D3 and vitamin K2 on bone loss prevention have been reported. This study evaluates the effects of vitamin D3 and vitamin K2 supplementation in conjunction with conventional periodontal therapy (scaling and root planing [SRP]) on gingival interleukin (IL)-1ß and IL-10, serum bone alkaline phosphatase (B-ALP) and tartrate-resistant acid phosphatase 5b (TRAP-5b), and calcium and alveolar bone levels in rats with experimentally induced periodontitis. METHODS: Seventy-two rats were divided into the following groups: 1) healthy; 2) periodontitis; 3) SRP; 4) SRP + vitamin D3; 5) SRP + vitamin K2; and 6) SRP + vitamins K2 and D3. Periodontitis was induced by ligature placement for 7 days, and vitamin K2 (30 mg/kg) and/or vitamin D3 (2 µg/kg) were administered for 10 days in the SRP + vitamin D3, SRP + vitamin K2, and SRP + vitamins K2 and D3 groups by oral gavage. On day 18, the animals were sacrificed, serum B-ALP, TRAP-5b, and calcium levels were measured, gingiva specimens were extracted for IL-1ß and IL-10 analysis, and distances between the cemento-enamel junction and alveolar bone crest were evaluated. RESULTS: Alveolar bone levels in the periodontitis group were significantly greater than those in the other five groups. No significant differences were found in gingival IL-1ß and IL-10, serum B-ALP and TRAP-5b, and calcium and alveolar bone levels between the groups receiving SRP and vitamins and the group receiving SRP alone. CONCLUSION: Within the limitations of this study, vitamin D3 and K2 alone or in combination did not affect gingival IL-1ß and IL-10, serum B-ALP and TRAP-5b levels, or alveolar bone compared with conventional periodontal therapy alone.

Bizarre tooth surface loss and the Miswak stick.

Tooth surface loss can present in a variety of ways, some of which can appear rather strange on first examination. This case report demonstrates an unusual presentation of tooth surface loss (TSL) and its subsequent treatment. This loss of hard dental tissue appeared to be affecting the whole of the patient's remaining dentition, both lingually and buccally. Detailed questioning revealed the origins of this problem which turned out to be due to excessive use of an intra-oral Miswak chewing stick. Cinical Relevance: This article will enable clinicians to understand the importance of specific, targeted history-taking, involving a rare case of tooth surface loss as well as the use of minimally destructive restoration composites and a fibre-reinforced composite bridge.

Alveolar bone regeneration potential of a traditional Chinese medicine, Bu-Shen-Gu-Chi-Wan, in experimental periodontitis.

BACKGROUND AND OBJECTIVE: The aim of this study was to investigate the effect of a traditional Chinese medicine, Bu-Shen-Gu-Chi-Wan, on experimental periodontitis and bone regeneration in rat. MATERIAL AND METHODS: Sixty female Sprague-Dawley rats were divided equally into three groups: a healthy control group (Group N); a periodontitis group (Group P); and the Bu-Shen-Gu-Chi-Wan treatment group (Group T). A 0.2-mm wire was placed around the maxillary first molar and Porphyromonas gingivalis was injected into the gingival sulcus. Rats in different groups were administered 0.9% normal saline or Bu-Shen-Gu-Chi-Wan solution (4 g/kg of body weight, for three alternate days), and the animals were killed after 4 wk. Morphological analysis of alveolar bone rebuilding was performed using micro-computed tomography (micro-CT) and stereomicroscopy, and the variation of inflammation in the periodontium was determined histologically. The serum levels of the proinflammatory cytokines interleukin-1beta (IL-1ß) and tumor necrosis factor-alpha (TNF-α) and of the bone-turnover biomarkers pyridinoline cross-linked carboxyterminal telopeptide of type I collagen (ICTP) and osteocalcin (OC) were determined using radioimmunoassays. RESULTS: After treatment with Bu-Shen-Gu-Chi-Wan, there were significant decreases in the levels of IL-1ß, TNF-α, ICTP and OC and decreased inflammatory infiltration in the periodontal tissues of Group T. significant changes in alveolar bone volume and density were detected by micro-CT, but stereomicroscopy did not detect a significant improvement of alveolar bone height. CONCLUSION: The data of the present study suggest that the traditional Chinese medicine, Bu-Shen-Gu-Chi-Wan, has anti-inflammatory function in experimental periodontitis and may simultaneously improve alveolar bone remodeling.

Effect of andiroba oil on periodontitis in Wistar rats.

PURPOSE: To evaluate the effects of andiroba oil on the periodontitis in rats. METHODS: The periodontitis was induced by the placement of cotton ligatures around the cervix of the second upper molars on fifteen rats, and waiting fifty days. The animals were randomly distributed into three groups: saline group, andiroba oil group and meloxican group, differentiated by substance used in the treatment of periodontitis. The groups received the respective substance by gavage for seven days, after the periodontitis induced. It was analyzed the score of inflammatory cells and the measurement from the cemento-enamel junction to the bone crest. RESULTS: The andiroba oil group (p=0.008) and meloxican group (p=0.0347) show a less score of inflammatory cells than saline group, however there weren't difference between them (p=0.2754). Regarding the analysis of measurement from the cemento-enamel junction to the bone crest, there was no difference between groups studied (p=0.3451). CONCLUSION: Andiroba oil decreased the quantity of inflammatory cells, however, it didn't have an effect on the measurement of alveolar bone loss, like the treatment with Meloxican®.

Effect of andiroba oil on periodontitis in Wistar rats

PURPOSE: To evaluate the effects of andiroba oil on the periodontitis in rats. METHODS: The periodontitis was induced by the placement of cotton ligatures around the cervix of the second upper molars on fifteen rats, and waiting fifty days. The animals were randomly distributed into three groups: saline group, andiroba oil group and meloxican group, differentiated by substance used in the treatment of periodontitis. The groups received the respective substance by gavage for seven days, after the periodontitis induced. It was analyzed the score of inflammatory cells and the measurement from the cemento-enamel junction to the bone crest. RESULTS: The andiroba oil group (p=0.008) and meloxican group (p=0.0347) show a less score of inflammatory cells than saline group, however there weren't difference between them (p=0.2754). Regarding the analysis of measurement from the cemento-enamel junction to the bone crest, there was no difference between groups studied (p=0.3451). CONCLUSION: Andiroba oil decreased the quantity of inflammatory cells, however, it didn't have an effect on the measurement of alveolar bone loss, like the treatment with Meloxican®.

Effects of electrical stimulation on periodontal tissue remodeling in rats.

BACKGROUND AND OBJECTIVE: Electric current is used to promote wound healing. However, it is unclear whether electrical stimulation contributes to gingival tissue remodeling. This study examined the effects of electrical stimulation on gingival tissue remodeling in a rat periodontitis model. MATERIAL AND METHODS: Male Wistar rats (n = 28, 8 wks of age) were divided into four groups of seven rats each. The control group did not receive any treatment for 6 wks. In the other groups, periodontitis was ligature-induced for 4 wks. After 4 wks, the rats with periodontitis were given daily electrical stimulation of 0, 50 or 100 µA for 2 wks. RESULTS: The periodontitis group stimulated with 0 µA showed a higher density of polymorphonuclear leukocytes and a lower density of collagen in gingival tissue compared with the control group (p < 0.05). The two remaining groups treated with 50 or 100 µA of electrical stimulation exhibited a lower density of polymorphonuclear leukocytes (p < 0.05) and a higher density of collagen than the group stimulated with 0 µA (p < 0.05). They also showed higher expression of fibroblast growth factor-2 than the group treated with 0 µA of electrical stimulation (p < 0.05). CONCLUSION: Electric stimulation may offer a novel approach to promote gingival tissue remodeling in periodontal lesions.

Four-year results following treatment of intrabony periodontal defects with an enamel matrix derivative alone or combined with a biphasic calcium phosphate.

The aim of this study was to evaluate the 4-year clinical outcomes following regenerative surgery in intrabony defects with either EMD + BCP or EMD. Twenty-four patients with advanced chronic periodontitis, displaying one-, two-, or three-walled intrabony defect with a probing depth of at least 6 mm, were randomly treated with either EMD + BCP (test) or EMD alone (control). The following clinical parameters were evaluated at baseline, at 1 year and at 4 years after regenerative surgery: plaque index, gingival index, bleeding on probing, probing depth, gingival recession, and clinical attachment level (CAL). The primary outcome variable was CAL. No differences in any of the investigated parameters were observed at baseline between the two groups. The test group demonstrated a mean CAL change from from 10.8 ± 1.6 mm to 7.4 ± 1.6 mm (p < 0.001) and to 7.6 ± 1.7 mm (p < 0.001) at 1 and 4 years, respectively. In the control group, mean CAL changed from 10.4 ± 1.3 at baseline to 6.9 ± 1.0 mm (p < 0.001) at 1 year and 7.2 ± 1.2 mm (p < 0.001) at 4 years. At 4 years, two defects in the test group and three defects in the control group have lost 1 mm of the CAL gained at 1 year. Compared to baseline, at 4 years, a CAL gain of ≥3 mm was measured in 67% of the defects (i.e., in 8 out of 12) in the test group and in 75% of the defects (i.e., in 9 out of 12) in the control group. There were no statistically significant differences in any of the investigated parameters at 1 and at 4 years between the two groups. Within their limits, the present results indicate that: (a) the clinical improvements obtained with both treatments can be maintained over a period of 4 years, and (b) in two- and three-walled intrabony defects, the addition of BCP did not additionally improve the outcomes obtained with EMD alone. In two- and three-walled intrabony defects, the combination of EMD + BCP did not show any advantage over the use of EMD alone.

Xenogeneic collagen matrix with coronally advanced flap compared to connective tissue with coronally advanced flap for the treatment of dehiscence-type recession defects.

BACKGROUND: For root coverage therapy, the connective tissue graft (CTG) plus coronally advanced flap (CAF) is considered the gold standard therapy against which alternative therapies are generally compared. When evaluating these therapies, in addition to traditional measures of root coverage, subject-reported, qualitative measures of esthetics, pain, and overall preferences for alternative procedures should also be considered. This study determines if a xenogeneic collagen matrix (CM) with CAF might be as effective as CTG+CAF in the treatment of recession defects. METHODS: This study was a single-masked, randomized, controlled, split-mouth study of dehiscence-type recession defects in contralateral sites; one defect received CTG+CAF and the other defect received CM+CAF. A total of 25 subjects (8 male, 17 female; mean age: 43.7 +/- 12.2 years) were evaluated at 6 months and 1 year. The primary efficacy endpoint was recession depth at 6 months. Secondary endpoints included traditional periodontal measures, such as width of keratinized tissue and percentage of root coverage. Subject-reported values of pain, discomfort, and esthetic satisfaction were also recorded. RESULTS: At 6 months, recession depth was on average 0.52 mm for test sites and 0.10 mm for control sites. Recession depth change from baseline was statistically significant between test and control, with an average of 2.62 mm gained at test sites and 3.10 mm gained at control sites for a difference of 0.4 mm (P = 0.0062). At 1 year, test percentage of root coverage averaged 88.5%, and controls averaged 99.3% (P = 0.0313). Keratinized tissue width gains were equivalent for both therapies and averaged 1.34 mm for test sites and 1.26 mm for control sites (P = 0.9061). There were no statistically significant differences between subject-reported values for esthetic satisfaction, and subjects' assessments of pain and discomfort were also equivalent. CONCLUSION: When balanced with subject-reported esthetic values and compared to historical root coverage outcomes reported by other investigators, CM+CAF presents a viable alternative to CTG+CAF, without the morbidity of soft tissue graft harvest.

Cross-sectional study of vitamin D and calcium supplementation effects on chronic periodontitis.

BACKGROUND: A low dietary intake of vitamin D and calcium hastens bone loss and osteoporosis. Because vitamin D metabolites may also alter the inflammatory response and have antimicrobial effects, we studied whether the use of vitamin D and calcium supplements affects periodontal disease status. METHODS: A cohort of 51 subjects receiving periodontal maintenance therapy was recruited from two dental clinics; 23 were taking vitamin D (>or=400 IU/day) and calcium (>or=1,000 mg/day) supplementation, and 28 were not taking such supplementation. All subjects had at least two interproximal sites with >or=3 mm clinical attachment loss. Daily calcium and vitamin D intake (from food and supplements) were estimated by nutritional analysis. The following clinical parameters of periodontal disease were recorded for the mandibular posterior teeth: gingival index, probing depth, cemento-enamel junction-gingival margin distance (attachment loss), bleeding on probing, and furcation involvement. Posterior photostimulable-phosphor bitewing radiographs were taken to determine cemento-enamel junction-alveolar crest distances (alveolar crest height loss). Data were analyzed with a repeated-measures multivariate analysis of variance. RESULTS: Compared to subjects who did not take vitamin D and calcium supplementation, supplement takers had shallower probing depths, fewer bleeding sites, lower gingival index values, fewer furcation involvements, less attachment loss, and less alveolar crest height loss. The repeated-measures analysis indicated that collectively these differences were borderline significant (P = 0.08). CONCLUSIONS: In these subjects receiving periodontal maintenance therapy, there was a trend for better periodontal health with vitamin D and calcium supplementation. More expanded longitudinal studies are required to determine the potential of this relationship.

Evaluation of fracture resistance in simulated immature teeth using Resilon and Ribbond as root reinforcements--an in vitro study.

BACKGROUND/AIM: To compare the reinforcement and strengthening ability of resilon, gutta-percha, and ribbond in endodontically treated roots of immature teeth. MATERIAL AND METHODS: Sixty five freshly extracted human maxillary anterior teeth were prepared with a Peeso no. 6 to simulate immature teeth (Cvek's stage 3 root development). After instrumentation, each root was irrigated with sodium hypochlorite and with ethylene diamino tetra acetic acid to remove the smear layer. To simulate single visit apexification technique a 4-5 mm white Pro Root mineral trioxide aggregate plug was placed apically using schilder carrier. The teeth were divided into three experimental groups and one control group. Group I--control group (root canals instrumented but not filled); Group II--backfilled with thermoplastisized gutta-percha using AH plus sealer; Group III--reinforced with Resilon using epiphany sealer; Group IV--reinforced with Ribbond fibers using Panavia F luting cement. A Universal Testing Machine was used to apply a load, at the level of the lingual cementoenamel junction with a chisel-shaped tip The peak load to fracture was recorded and statistical analysis was completed using student's t-test. RESULTS: Values of peak load to fracture were 1320.8, 1604.88, 1620, and 1851 newtons for Group I to Group IV respectively. The results of student's t-test, revealed no significant difference (P > 0.05,) between Group II and Group III. Comparison between Group IV and Group III and between Group IV and Group II revealed highly significant difference (P > 0.001). CONCLUSIONS: Teeth reinforced with Ribbond fibers using Panavia F luting cement showed the highest resistance to fracture. Resilon could not strengthen the roots and showed no statistically significant difference when compared with thermoplastisized gutta-percha in reinforcing immature tooth when tested with universal testing machine in an experimental model of immature tooth.

Relationship between root caries and alveolar bone loss in the first wet-rice agriculturalists of the Yayoi period in Japan.

OBJECTIVE: The people of the Yayoi period (5th C b.c.-3rd C a.d.), who were the first wet-rice agriculturalists in ancient Japan, had carious lesions that were most frequently located on the root surfaces of their teeth. Root surface exposure is a prerequisite for this type of decay, and alveolar bone loss is the main cause of such exposure. Therefore, we identify the factors associated with root caries, and examine the relationship between root caries and alveolar bone loss in the people of the Yayoi period. MATERIALS AND METHODS: This study was performed using 263 sets of ancient skeletal remains that are believed to be from the Yayoi period and that were excavated at 49 archaeological sites in western Japan. Using 5010 teeth found among the remains, we analysed the relationship between the prevalence of root caries and the cemento-enamel junction-alveolar crest (CEJ-AC) distance. RESULTS: The prevalence of root caries and the mean number of teeth with root caries per person were significantly correlated with age, the presence of coronal caries and the mean CEJ-AC distance per person. We also found that as the mean CEJ-AC distance per tooth surface increased, the percentage of the root surface affected by caries increased. Moreover, after excluding the lingual (palatal) side, the mean CEJ-AC distance per surface was significantly greater for those tooth surfaces with root caries. CONCLUSION: We present the first evidence that the occurrence of root caries correlated with the CEJ-AC distance in the Yayoi people of Japan.

EDTA gel root conditioning: lack of effect on clinical and radiographic outcomes of intrabony defect treatment with enamel matrix derivative.

BACKGROUND: The adjunctive use of enamel matrix derivative (EMD) in the surgical therapy of intrabony defects results in improved outcomes compared to surgical debridement alone. However, the role of EDTA root conditioning in EMD therapy has not been investigated. The purpose of this study was to compare the 12-month outcomes of EMD application with and without EDTA root conditioning in intrabony defect surgical therapy. METHODS: Twenty-eight chronic periodontitis patients, each contributing a 2- or 3-wall intrabony defect (> or = 4 mm deep and > or = 2 mm wide), participated. Patients consecutively received surgical treatment with either EMD alone (first 13 patients) or EMD + EDTA (subsequent 15 patients). Probing depth (PD), clinical attachment level (CAL), and gingival margin position, i.e., recession (REC) were the clinical parameters recorded. Recorded radiographic parameters were the distances from 1) cemento-enamel junction to bone crest (CEJ to BC), 2) CEJ to base of the defect (CEJ to BD), and 3) BC to BD. RESULTS: Intragroup analysis showed that both EMD alone and EMD + EDTA led to significant PD reduction, CAL gain, and REC increase 1 year postoperatively. Both groups had >60% mean radiographic defect resolution (change in BC to BD). None of the recorded parameters were significantly different between the two groups, either at baseline or postoperatively. CONCLUSIONS: These results suggest that clinical and radiographic outcomes of intrabony defect EMD therapy do not depend on the use of EDTA gel root conditioning. The potential contribution of EDTA gel root conditioning to the histological outcomes reported with EMD therapy remains to be determined.

A histopathologic investigation on the effects of electrical stimulation on periodontal tissue regeneration in experimental bony defects in dogs.

BACKGROUND: One endpoint of periodontal therapy is to regenerate the structure lost due to periodontal disease. In the periodontium, gingival epithelium is regenerated by oral epithelium. Underlying connective tissue, periodontal ligament, bone, and cementum are derived from connective tissue. Primitive connective tissue cells may develop into osteoblasts and cementoblasts, which form bone and cementum. Several procedural advances may support these regenerations; however, the regeneration of alveolar bone does not always occur. Therefore, bone stimulating factors are a main topic for periodontal reconstructive research. The present study was designed to examine histopathologically whether the application of an electrical field could demonstrate enhanced alveolar and cementum regeneration and modify tissue factors. METHODS: Seven beagle dogs were used for this experiment. Mandibular left and right sides served as control and experimental sides, respectively, and 4-walled intrabony defects were created bilaterally between the third and fourth premolars. The experimental side was treated with a capacitively coupled electrical field (CCEF) (sinusoidal wave, 60 kHz, and 5 V peak-to-peak), applied for 14 hours per day. The following measurements were performed on the microphotographs: 1) the distance from the cemento-enamel junction to the apical notch (CEJ-AN) and from the crest of newly formed bone (alveolar ridge) to the apical notch (AR-AN); 2) the thickness of new cementum in the apical notch region; and 3) the length of junctional epithelium. The following histopathologic parameters were assessed by a semiquantitative subjective method: 1) inflammatory cell infiltration (ICI); 2) cellular activity of the periodontal ligament; 3) number and morphology of osteoclasts; 4) resorption lacunae; and 5) osteoblastic activity. RESULTS: The results showed that the quantity of new bone fill and the mean value of the thickness of the cementum were significantly higher for the experimental side (P < 0.01). The location of the base of the pocket was positioned more coronally with respect to the apical point of the coronal notch in the experimental side (statistically significant P < 0.01). The length of the junctional epithelium and the number of osteoclasts were higher in the stimulated side than the coronal side; these findings were also statistically significant (P < 0.01). The comparison of the electrically stimulated versus non-stimulated mandibles with the semiquantitative subjective method demonstrated statistically significant differences in defined histopathologic parameters, except for osteoclast morphologies (P > 0.05). CONCLUSIONS: This study demonstrated that the CCEF method has the potential to produce reconstructive effects and bone deposits. Further investigations with respect to the theoretical determination of local field parameters of the periodontal tissue complex, such as permittivity, conductivity, strength of the field electrical stimulation applied to the periodontal field current density, wavelength, and signal frequency appropriate for this field, should be undertaken. Using different electromotive forces alone or in combination with bone graft materials, guided tissue regeneration techniques, and dental implants may achieve a new dimension in periodontal therapy in the near future.

Microleakage of compomer restorations in primary teeth after preparation with bur or air abrasion.

This study compared the degree of marginal leakage of a compomer in Class V cavities of human primary molars prepared by a conventional dental bur and air abrasion with or without acid etching. Fifty-six non-carious extracted primary molars were randomly divided into four groups (n=14) to be prepared by four techniques: Group-1: Bur followed by acid etching: Class V cavity preparations were placed on the buccal surfaces of each tooth using a high-speed handpiece. The preparations were 1.5-mm deep, 3-mm long and 2-mm wide, with the occlusal margin in enamel and the cervical margin extending 0.5 mm below the cementoenamel junction. The preparations were acid etched with 37% phosphoric acid starting at the enamel margins for 30 seconds and rinsed with water for 20 seconds. The preparations were then restored with Compoglass F. 2-Group 2: Bur: The preparations and the treatment procedures were the same as in Group 1, with the exception of 37% phosphoric acid application. Group 3: Air abrasion followed by acid etching: Class V cavity preparations were placed on the buccal surfaces of each tooth using a handpiece of an air-abrasive system (PrepStart, Danville Engineering). The system was supplied with dry compressed air at 80 psi. In all tests, the air-abrasion system was operated with an 80 degrees-angle handpiece tip and 50-mm aluminum oxide particles. A tip with a 0.38-mm inner diameter was used at a 2-mm distance. The treatment procedures were the same as in Groups 1 and 2. Group 4: Air abrasion: The preparations and treatment procedures were the same as in Group 3, with the exception of 37% phosphoric acid. After finishing the restorations, the teeth were stored in distilled water at 37 degrees C for 24 hours. The samples were thermocycled for 500 cycles between 5 degrees C and 55 degrees C with a dwell time of 30 seconds. The samples were then immersed in 0.5 percent basic fuchsin dye for 24 hours at 37 degrees C. The surface-adhered dye was then rinsed in tap water and the teeth were embedded in a chemically-activated acrylic resin and bisected longitudinally in a mesiodistal direction with a low speed diamond disk. Each section was examined under a stereomicroscope (Nikon, Tokyo, Japan) at 20x magnification. The data were analyzed statistically by Kruskal-Wallis analysis of variance to determine any statistical significant differences in microleakage scores among the groups at a p-value of 0.05. Also, the enamel versus cementum-dentin microleakage scores of each group were compared using z-test at the 0.05 significance level. There was no statistically significant difference among the groups (p>0.05), but a statistical difference between enamel and cementum-dentin surfaces was evaluated (p<0.05).

Studies of dental root surface caries. 2: The role of cementum in root surface caries.

Artificial caries lesions were produced in roots of teeth using an acetate buffer system, when the layer of cementum was either normal in thickness, excessively thickened by hypercementosis, or had been removed completely. The rates of lesion progression were measured in each case using polarized light microscopy to measure lesion depth. Analysis of calcium (Ca) and phosphorus (P) loss during the demineralizing process was carried out. The removal of cementum was found to significantly increase the initial rate of penetration of the lesion into the root, although this rate progressively reduced to a level consistent with that found in normal roots after seven days of demineralization. The overall depth remained consistently greater than that observed in normal roots, or when lesions were produced entirely within hyperplastic cementum. Chemical analysis also showed removal of cementum resulted in an initial doubling of the Ca and P lost from the root surface. Prior direct exposure of segments of normal roots to the oral environment was found not to significantly alter the rate of artificial lesion progression, in comparison with that in the originally protected segment of the root surface. It was concluded that an intact cementum layer has the intrinsic ability to protect the underlying dentine of exposed tooth roots against acidic demineralization and that prior exposure to the oral environment does not significantly alter this ability.

Enamel hypomineralization of permanent first molars: a morphological study and survey of possible aetiological factors.

OBJECTIVES: The aim of this study was to investigate the morphological appearance of severe hypomineralized enamel of permanent first molars by means of polarized light microscopy, and to estimate the possible time, severity and longevity of the insult. Furthermore, the aim was to survey some commonly implicated aetiological factors in order to gain knowledge about possible pathogenesis of the enamel disturbances which could be compared with future epidemiological studies. SAMPLE AND METHODS: Seventy-three teeth, which had been extracted due to severe hypomineralizations of the enamel, were collected and serially cut longitudinally in a bucco-lingual direction. The sections were examined in polarized light, dry and embedded in water. The children were also examined with respect to the demarcated opacities of other permanent teeth than those that were extracted. The parents were asked about their health during the mother's pregnancy, the time of gestation, birth weight and any complications. They were also asked about the child's health during the first 2 years of its life, the length of time of breast-feeding and also about fluoride supplements. RESULTS: The hypomineralized areas extended cervically from the cusps, comprising about half of the buccal and lingual sides. The cervical borders to normal enamel were well defined and mainly followed the lines of Hunter-Schreger. The hypomineralized zones were covered by thin well-mineralized enamel. The majority of the children had demarcated opacities of all their first molars and also of some permanent incisors. No obvious correlation to the anamnestic data could be found. CONCLUSIONS: The hypomineralized enamel in the investigated teeth demonstrated areas of porosity of varying degrees. The yellow/brown defects were more porous than the white-cream and extended through the whole enamel layer, while the white-cream opacities were situated in the inner parts of the enamel. There had probably been an interacting disturbance of short duration of systemic origin of the activity of the ameloblast during the first 2 years of the child's life, resulting in chronological dispersed hypomineralized demarcated opacities in the developing teeth.