Impact of Type 2 Diabetes Mellitus on the Occurrence of Vertical Root Fracture: A Case Control Study

INTRODUCTION

The aim of this case-control study was to examine the relationship between type 2 diabetes mellitus (DM) and the occurrence of VRFs. The crack extension, dentin sclerosis, and chemical characteristics of root dentin in teeth with VRF from patients with/without DM were also compared.

METHODS

One hundred and thirty-two patients diagnosed with VRF in crowned root filled posterior teeth were selected. The study was conducted in 2 parts. In Part-1: The cases were matched with control teeth (1:1) for age (±5 years), sex, tooth type, apical extent of root filling, time period after root filling to a diagnosis of VRF, presence or absence of intracanal post and abutment status. The presence or absence of type 2 DM (HbA1c > 6.5) was recorded. In Part-2: The extracted teeth with VRF from the case control study were used to evaluate the extension of VRF, presence of sclerotic dentin and isthmus using a microscopic analysis; while the levels of pentosidine, collagen cross-linking ratio and mineral-collagen ratio were determined by Fourier-transform infrared spectroscopy. The distribution of DM between cases and controls was analyzed using Pearson Chi-Square test and Odds Ratio estimated. Chemical composition data was analyzed using Mann-Whitney test. The extent of sclerotic dentin was analyzed using Pearson Chi-Square test.

RESULTS

When compared to patients without DM, patients with DM had 2.67 (95% CI: 1.6-4.45) folds higher odds for occurrence of VRF. Pentosidine (P = .014), collagen cross-linking ratio(P = .047), mineral-collagen ratio (P = .009) and sclerotic dentin extent (P = .0009) were significantly higher in patients with DM and VRF.

CONCLUSIONS

Type 2 DM was more often associated with VRFs in root canal treated teeth with crowns. Root dentin from patients with type 2 DM and VRF had higher levels of pentosidine, collagen cross-linking ratio, mineral to collagen ratio and sclerotic dentin.

Sensory nerves, but not sympathetic nerves, promote reparative dentine formation after dentine injury via CGRP-mediated angiogenesis: An in vivo study

AIM

Dental pulp is richly innervated by nerve fibres, which are mainly involved in the sensation of pain. Aside from pain sensation, little is known regarding the role of dental innervation in reparative dentine formation. We herein generated a mouse model of experimental dentine injury to examine nerve sprouting within the odontoblast and subodontoblastic layers and investigated the potential effects of this innervation in reparative dentinogenesis.

METHODOLOGY

Mouse tooth cavity model (bur preparation + etching) was established, and then nerve sprouting, angiogenesis and reparative dentinogenesis were determined by histological and immunofluorescent staining at 1, 3, 7, 14 and 28 days postoperatively. We also established the mouse-denervated molar models to determine the role of sensory and sympathetic nerves in reparative dentinogenesis, respectively. Finally, we applied calcitonin gene-related peptide (CGRP) receptor antagonist to analyse the changes in angiogenesis and reparative dentinogenesis.

RESULTS

Sequential histological results from dentine-exposed teeth revealed a significant increase in innervation directly beneath the injured area on the first day after dentine exposure, followed by vascularisation and reparative dentine production at 3 and 7 days, respectively. Intriguingly, abundant type H vessels (CD31+ Endomucin+ ) were present in the innervated area, and their formation precedes the onset of reparative dentine formation. Additionally, we found that sensory denervation led to blunted angiogenesis and impaired dentinogenesis, while sympathetic denervation did not affect dentinogenesis. Moreover, a marked increase in the density of CGRP+ nerve fibres was seen on day 3, which was reduced but remained elevated over the baseline level on day 14, whereas the density of substance P-positive nerve fibres did not change significantly. CGRP receptor antagonist-treated mice showed similar results as those with sensory denervation, including impairments in type H angiogenesis, which confirms the importance of CGRP in the formation of type H vessels.

CONCLUSIONS

Dental pulp sensory nerves act as an essential upstream mediator to promote angiogenesis, including the formation of type H vessels, and reparative dentinogenesis. CGRP signalling governs the nerve-vessel-reparative dentine network, which is mostly produced by newly dense sensory nerve fibres within the dental pulp.

Radiographic evaluation of secondary dentin formation in lower premolars for forensic age diagnosis of 18 years in a sample of south Indian adolescents and young adults

There has been an increase in the need for alternate methods of dental age assessment, especially for the forensic age diagnosis of the 18th year of life. This is due to the completion of the third molar development before 18 years or the agenesis or therapeutic extractions of the third molars. The present study aimed to verify whether the secondary dentin formation in lower premolars can be used to determine the completion of the 18th year of life in a sample of South Indian adolescents and young adults. For this purpose, 800 orthopantomograms of 400 male and 400 female South Indian subjects aged 14- 22 were evaluated. The characteristics of the secondary dentin formation were determined in all mandibular premolars using the stage classification according to Olze et al (Int J Legal Med 126(4):615-21). The results showed that when stage 3 of secondary dentin formation was reached in the first premolars, the probability of the subject completing the 18th year of life was very high. However, only a few individuals in the studied population were at stage 3. Therefore, proceeding cautiously with this degenerative change in lower premolars is advised due to the higher inter-examiner differences. It is also recommended to use this method in conjunction with other age estimation methods. Further research should investigate other degenerative characteristics in the studied population.

Reparative Dentin Formation Following Dental Pulp Capping is Mediated by TNFR1 In Vivo

INTRODUCTION

Tumor necrosis factor (TNF)-α is a pro-inflammatory cytokine that promotes biomineralization in vitro in dental pulp cells. However, the role of TNF-α-TNF receptor 1 (TNFR1) signaling in reparative dentin formation and related inflammatory pathways is not known. Therefore, the aim of this study was to evaluate the role of the TNF-α-TNFR1 axis in dental pulp repair following pulp capping in vivo.

METHODS

Dental pulp repair response of genetically deficient TNF-α receptor-1 mice (TNFR1-/-; n = 20) was compared with that of C57Bl6 mice (wild type [WT]; n = 20). Pulp capping was performed with mineral trioxide aggregate on the mandibular first molars of mice. After 7 and 70 days, tissues were collected and stained with hematoxylin and eosin for histopathological and histometric evaluation, and assessed by the Brown and Brenn methods for histomicrobiological analysis and by immunohistochemistry to localize TNF-α, Runt-related transcription factor 2, Dentin Sialoprotein (DSP) and Osteopontin (OPN) expression.

RESULTS

Compared with WT mice, TNFR1-/- mice showed significantly decreased reparative dentin formation with a lower mineralized tissue area (P < .0001). Unlike WT mice, TNFR1-/- mice also exhibited significant dental pulp necrosis, neutrophil recruitment, and apical periodontitis formation (P < .0001) without bacterial tissue invasion. TNFR1-/- animals further exhibited decreased TNF-α, DSP, and OPN expression (P < .0001), whereas Runt-related transcription factor 2 expression was unchanged (P > .05).

CONCLUSION

The TNF-α-TNFR1 axis is involved in reparative dentin formation following dental pulp capping in vivo. Genetic ablation of TNFR1 modified the inflammatory process and inhibited the expression of the DSP and OPN mineralization proteins, which culminated in dental pulp necrosis and development of apical periodontitis.

Nano eggshell-based slurry as a direct pulp-capping material: In vitro characterization and histopathological assessment in an experimental animal model

AIM

Pulp vitality is essential for tooth integrity. Following pulp exposure, choosing a suitable pulp-capping material is crucial to maintain pulp vitality. However, the reparative dentine bridge created by calcium hydroxide (Ca(OH)2 ) is generally porous and incomplete. The aim of the current study is to assess the in vitro and in vivo bioactivities of nano eggshell-based slurry (NES), using NES as a direct pulp-capping material, compared with Ca(OH)2 in rabbit animal model.

METHODOLOGY

Nano eggshell powder (NE) was characterized for particle morphology, chemical composition and ion release. In vitro bioactivity was tested by immersion in simulated body fluid (SBF) for 7 days. For histopathological evaluation, 36 adult New Zealand rabbits (72 pulp exposures) were divided into nine groups (n = 8) according to the pulp-capping material (NES, Ca(OH)2 and no capping as negative control group) and the animals were sacrificed after 7, 14 or 28 days. The pulps of the two lower central incisors were exposed and then directly capped by Ca(OH)2 or NES or left untreated. The cavities were then sealed with glass ionomer cement. Teeth were collected for histopathological evaluation using an optical microscope. Pulp haemorrhage, inflammation, fibrosis and calcific bridge formation were assessed. Results were statistically analysed using anova and Tukey's tests.

RESULTS

Nano eggshell particles were spherical with a 20 nm diameter and were composed mainly of calcite. Statistical analysis showed that there was a significant increase in the release of all investigated ions between days 1 and 28, except for copper. NES group showed a significantly higher release of all elements as compared to Ca(OH)2 . Environmental scanning electron microscope micrographs of NES incubated for 7 days in SBF showed the formation of HAp with a Ca/P ratio (1.686). For histopathological evaluation, the difference between groups was statistically significant. At day 28, 75% of the pulps of the Ca(OH)2 group showed mild calcific bridge in comparison with 100% moderate calcific bridge in the NES group. The NES group showed significantly less inflammation at days 7 and 28, and higher fibrosis at day 7 compared with Ca(OH)2 .

CONCLUSIONS

Nano eggshell-based slurry represents a promising novel direct pulp-capping material with favourable pulp tissue response.

3D-printed microgels supplemented with dentin matrix molecules as a novel biomaterial for direct pulp capping

OBJECTIVES

To develop a 3D-printed, microparticulate hydrogel supplemented with dentin matrix molecules (DMM) as a novel regenerative strategy for dental pulp capping.

MATERIALS AND METHODS

Gelatin methacryloyl microgels (7% w/v) mixed with varying concentrations of DMM were printed using a digital light projection 3D printer and lyophilized for 2 days. The release profile of the DMM-loaded microgels was measured using a bicinchoninic acid assay. Next, dental pulp exposure defects were created in maxillary first molars of Wistar rats. The exposures were randomly capped with (1) inert material - negative control, (2) microgels, (3) microgels + DMM 500 µg/ml, (4) microgels + DMM 1000 µg/ml, (5) microgels + platelet-derived growth factor (PDGF 10 ng/ml), or (6) MTA (n = 15/group). After 4 weeks, animals were euthanized, and treated molars were harvested and then processed to evaluate hard tissue deposition, pulp tissue organization, and blood vessel density.

RESULTS

All the specimens from groups treated with microgel + 500 µg/ml, microgel + 1000 µg/ml, microgel + PDGF, and MTA showed the formation of organized pulp tissue, tertiary dentin, newly formed tubular and atubular dentin, and new blood vessel formation. Dentin bridge formation was greater and pulp necrosis was less in the microgel + DMM groups compared to MTA.

CONCLUSIONS

The 3D-printed photocurable microgels doped with DMM exhibited favorable cellular and inflammatory pulp responses, and significantly more tertiary dentin deposition.

CLINICAL RELEVANCE

3D-printed microgel with DMM is a promising biomaterial for dentin and dental pulp regeneration in pulp capping procedures.

SVCT2-GLUT1-mediated ascorbic acid transport pathway in rat dental pulp and its effects during wound healing

Ascorbic acid (AA; vitamin C) plays a crucial role in the biosynthesis and secretion of collagen to produce the organic matrix of hard tissues. Nevertheless, the detailed mechanism by which AA induces reparative dentinogenesis is still unknown. This study aimed to investigate the pathway and function of AA during wound healing in a rat pulpotomy model. Sodium-dependent vitamin C transporter (SVCT) 2 and glucose transporter (GLUT) 1 were detected in odontoblasts, endothelial cells, and nerve fibers in normal pulp tissues. SVCT2 and GLUT1 were also expressed in odontoblast-like cells in pulpotomized tissues of Wistar rats, and immunopositive cells of SVCT2 were significantly increased at 5 days after pulpotomy (p < 0.05). By contrast, osteogenic disorder Shionogi (ODS) rats, which cannot generate AA, also expressed SVCT2 and GLUT1 in normal and wound healing conditions. However, in ODS rats, when compared with the AA-addition group, the formation of dentin bridges in the AA-loss group was not evident, a layer of osteopontin was significantly increased beneath the wound surface (p < 0.05), and alpha smooth muscle actin at the odontoblast-like cells observed along this layer was significantly increased (p < 0.05), but not Nestin. Moreover, the amounts of type 1 collagen generated in the reparative dentin and beneath the wound healing site were significantly diminished (p < 0.05). Macrophages expressing CD68 and CD206 increased beneath the wound site. Hence, AA may be involved in odontoblast-like cell differentiation and anti-inflammatory response during dental pulp wound healing. Our results provide new insights into the function of AA through SVCT2 and GLUT1 in reparative dentinogenesis and may help in developing new therapeutic targets for dental pulpal disease.

Age Estimation Using Maxillary Central Incisor Analysis on Cone Beam Computed Tomography Human Images

Forensic dentistry plays an important role in human identification, and dental age estimation is an important part of the process. Secondary dentin deposition throughout an individual's lifetime and consequent modification in teeth anatomy is an important parameter for age estimation procedures. The aim of the present study was to develop regression equations to determine age in adults by means of linear measurements and ratios on sagittal, coronal and axial slices of maxillary central incisors using cone bean computed tomography (CBCT). Multiplanar measurements of upper central incisors were taken for a sample of 373 CBCTs. Subsequently, one-way analysis of variance (ANOVA) and multivariate linear regressions were performed for age estimation. The equations obtained from axial linear measurements and ratios presented a standard error of the estimate (SEE) of ±10.9 years (R² = 0.49), and a SEE of ±10.8 years (R² = 0.50), respectively. The equation obtained for multiplanar linear measurements presented a SEE of ±10.9 years (R² = 0.52), while the equation for multiplanar ratios presented a SEE of ±10.7 years (R² = 0.51). Thus, CBCT measurements on upper central incisors were found to be an acceptable method for age estimation. Horizontal measurements, especially pulp measurements, improve the accuracy of age estimate equations.

Dentine matrix metalloproteinases as potential mediators of dentine regeneration

Matrix metalloproteinases (MMPs) have been implicated not only in the regulation of developmental processes but also in the release of biologically active molecules and in the modulation of repair during tertiary dentine formation. Although efforts to preserve dentine have focused on inhibiting the activity of these proteases, their function is much more complex and necessary for dentine repair than expected. The present review explores the role of MMPs as bioactive components of the dentine matrix involved in dentine formation, repair and regeneration. Special consideration is given to the mechanical properties of dentine, including those of reactionary and reparative dentine, and the known roles of MMPs in their formation. MMPs are critical components of the dentine matrix and should be considered as important candidates in dentine regeneration.

Clinical, radiographic, and histological evaluation of three different pulp-capping materials in indirect pulp treatment of primary teeth: a randomized clinical trial

OBJECTIVES

The aim of this randomized, controlled, three-arm parallel group, and double-blinded clinical trial was to evaluate the clinical, radiographic, and histopathological success of three different pulp-capping materials in one-stage indirect pulp treatment of primary teeth.

MATERIALS AND METHODS

The study included a total of 109 patients aged 5-9 years who had primary teeth with deep carious lesions and symptoms of reversible pulpitis. The teeth were divided into three groups according to the pulp-capping agents: (I) hard-setting calcium hydroxide (Dycal) (control group) (n = 36), (II) bioactive tricalcium silicate (Biodentine) (n = 37), and (III) resin-based tricalcium silicate (TheraCal LC) (n = 36). All the teeth were evaluated clinically and radiographically at 6, 12, 18, and 24 months postoperatively. A total of 23 primary mandibular second molars that were in their regular exfoliation period (24-40 months) were extracted and fixed in 10% formaldehyde solution. The specimens were evaluated histologically to assess the integrity of the odontoblastic layer, tertiary dentin formation quality of the dentin formed, severity of pulpitis, and other pulpal changes. Data were analyzed using Fisher's exact test, Pearson's chi-square test, and McNemar's test (p = 0.05).

RESULTS

At the end of the 24-month follow-up period, the clinical and radiographic success rates for Dycal, Biodentine, and TheraCal LC were 100%, 100%, and 93.3%, respectively, and there was no significant difference among the groups (p > 0.05). However, the TheraCal LC group was statistically unsuccessful when compared to the other groups with regard to the integrity of the odontoblastic layer, severity of pulpitis, and other pulpal changes in histological examination (p < 0.05).

CONCLUSION

Indirect pulp capping exhibited high clinical and radiographic success rates in the treatment of primary teeth regardless of the chosen pulp-capping agent. However, histological examination indicated that the pulp status was affected by the chosen capping material especially when selecting a resin-containing material such as TheraCal LC.

CLINICAL RELEVANCE

Resin-free calcium silicate-based materials appear to be more favorable in the indirect pulp treatment of primary teeth, particularly in young-age groups that require long-term success.

MODERN ASPECTS OF TRAUMATIC PULPITIS TREATMENT WITH THE USE OF BIOCERAMICS

OBJECTIVE

The aim: The research was to evaluate the effectiveness of acute traumatic pulpitis treatment with the use of bioceramics according to the results of a clinical study.

PATIENTS AND METHODS

Materials and methods: Acute traumatic pulpitis of 25 teeth in 25 patients aged 18-25 years were treated by biological direct pulp capping. In 13 patients of the main group, bioceramics was placed on the exposed pulp, and in 12 patients of the control group, calcium hydroxide paste was applied on the exposed pulp. Treatment effectiveness was evaluated according to the following criteria: the absence of clinical signs of pulpal inflammation, on X-ray - signs of dentinal bridge formation, the absence of periapical changes.

RESULTS

Results: The use of bioceramic material in patients of the main group provided a positive dynamic of treatment in 12 teeth. The need for re-treatment was diagnosed only in 1 clinical case (7.7%), in the control group - in 4 cases (33.3%).

CONCLUSION

Conclusions: Pulpitis treatment with the use of bioceramics provides preserving the functional properties of pulp, creation of a calcified barrier - dentin bridge and prevents the periodontal complications compared to the pulp capping with a material based on calcium hydroxide. The effectiveness of treatment in the main group was 92.3%, in the control - 66.7%.

Effect of Calcium Hydroxide Combinations with Green Tea Extract and Cocoa Pod Husk Extract on p38 MAPK and Reparative Dentine

AIM AND OBJECTIVE

The aim of this research is to analyze the effect of calcium hydroxide combinations with green tea extract and the combination of calcium hydroxide with cocoa pod husk extract on the activation of p38 MAPK and wide area of reparative dentin in mice dental.

MATERIALS AND METHODS

This study used 36 rats that were randomly divided into three treatment groups: positive control group was applied calcium hydroxide and aquades (group I), the test group was applied calcium hydroxide combined with cocoa pod husk extract (group II), and the next test group was applied using calcium hydroxide combined with green tea extract (group III); all the cavities were restored with RMGIC. On day 7 and 28, experimental animals from each treatment group were killed by peritoneal injection to see the activation of p38 MAPK, while reparative dentin was only seen on day 28.

RESULTS

The result of data analysis using Multiple Comparison Tukey HSD test showed significant difference between the positive control group and the test groups for the average p38 MAPK activation value on day 7 and 28. But there was no significant difference between two test groups. The same thing was obtained in the calculation of the average area of reparative dentin, where group I had the lowest value compared to groups II and III on day 28 with a significant difference. There was no significant difference between groups II and III.

CONCLUSION

The use of combination calcium hydroxide with green tea extract and combination calcium hydroxide with cocoa pod husk extract have significant effect on p38 MAPK activation and wide area of reparative dentin in mice dental.

CLINICAL SIGNIFICANCE

The use of combination calcium hydroxide with green tea extract and combination calcium hydroxide with cocoa pod husk extract have been proven to activate more p38 and form a wider reparative dentin.

Evaluation of Recombinant Human Platelet-Derived Growth Factor or Enamel Matrix Derivative Plus Calcium Hydroxide for Pulp Capping: A Randomized Controlled Human Clinical Trial

This in vivo study assessed calcium hydroxide's effect as a matrix carrier for recombinant human platelet-derived growth factor (rhPDGF) and enamel matrix protein (EMD) on pulp tissue healing following pulp capping. Intact premolar sites (n = 18) were included. Coronal access and pulpotomy were performed, and each tooth was exposed to the oral cavity for 1 hour before pulp capping was performed. Teeth were randomly assigned to one of the following pulp-capping groups (n = 6 each): Group 1 (CaOH₂ only); Group 2 (CaOH₂+EMD); and Group 3 (CaOH₂+rhPDGF). Coronal access cavities were then sealed. Immediate preoperative, postoperative, and 4-month follow-up radiographs were taken. At 4 months, teeth were extracted atraumatically and histomorphometric and micro-CT analyses were performed. Group 1 showed formation of thin, uneven, highly porous dentin-like structure with tunnel defects (average thickness: 0.18 to 0.19 mm). Lack of continuity of the newly formed tissue and interrupted communication tunnels were seen between the pulpal space and pulp-capping material. Group 2 showed formation of highly dense, nonporous, even-thickness dentin-like structure obliterating multiple areas of the pulp space (average thickness: 0.9 to 0.94 mm). Abundant odontoblast lacunae were present in the pulp and structure. Group 3 showed formation of an inconsistent, uneven dentin-like structure that appeared highly porous (average thickness: 1.04 to 1.05 mm). It was without tunneling, and abundant odontoblastic lacunae were present. No statistically significant differences were found between Groups 2 and 3, but both were richer in newly formed dentin-like structure with more thickness than Group 1 (P < .05). Addition of EMD to CaOH₂ can result in multiple root canal calcifications, mostly in the coronal and apical thirds of the canals. The calcified tissue does not appear to resemble secondary dentin in form, shape, amount, or density. Addition of rhPDGF to CaOH₂ may not cause root canal calcifications. The newly formed structure differs from secondary dentin in degree of mineralization, porosity, and density.

Regeneration of Secondary Dentin Using Recombinant Human Platelet-Derived Growth Factor and MTA for Pulp Capping: A Randomized Controlled Human Clinical Trial

This in vivo study assessed the effect of mineral trioxide aggregate (MTA) as a matrix carrier for recombinant human platelet-derived growth factor (rhPDGF) and enamel matrix protein (EMP) on pulp tissue healing following pulp capping. Eighteen intact human premolars scheduled for extraction were included. Coronal access and pulpotomy were performed, and each tooth was left exposed to the oral cavity for 1 hour before pulp capping was performed. Teeth were randomly assigned to one of the following pulp-capping groups (n = 6 each): Group 1 (MTA only); Group 2 (MTA+EMP); or Group 3 (MTA+rhPDGF). Coronal access cavities were then sealed. Immediate preoperative, postoperative, and 4-month follow-up radiographs were taken. At 4 months, the teeth were extracted atraumatically, and histomorphometric and micro-computed tomography (μCT) analyses were performed. Group 1 showed a thin, uneven, irregular dentin-like structure. Its average thickness was 0.3 ± 0.084 mm measured histologically and 0.29 ± 0.091 mm measured by μCT. Group 2 showed of a nonporous, even-thickness dentin-like structure with multiple root-canal obliterations. Highly dense, atubular dentin-like structures associated with presence of odontoblastic lacunae were seen. The structure's average thickness was 0.87 ± 0.09 mm (histologically) and 0.81 ± 0.17 mm (μCT). Group 3 showed a thick and complete 3D continuous seal of newly formed dentin-like structure covering the pulpal space. It resembled secondary dentin in form, porosity, and tubular structural organization, and its average thickness was 0.94 ± 0.02 mm (histologically) and 0.91 ± 0.09 mm (μCT). Groups 2 and 3 showed higher amounts of newly formed dentin-like structure, that was also thicker, than Group 1 (P < .05). No statistically significant differences in structure thickness were found between Groups 2 and 3. The nature of the structure can differ if rhPDGF or EMP is added to MTA for pulp-capping purposes. Combination of rhPDGF and MTA resulted in a newly formed structure resembling secondary dentin, whereas a combination of EMP and MTA produced a nonporous, highly dense dentinal-like structure associated with significant root-canal obliterations.

Expression of BSP-GFPtpz Transgene during Osteogenesis and Reparative Dentinogenesis

Bone sialoprotein (BSP) is a member of the SIBLING family with essential roles in skeletogenesis. In the developing teeth, although the expression and function of BSP in the formation of acellular cementum and periodontal attachment are well documented, there are uncertainties regarding the expression and function of BSP by odontoblasts and dentin. Reporter mice are valuable animal models for biological research, providing a gene expression readout that can contribute to cellular characterization within the context of a developmental process. In the present study, we examined the expression of a BSP-GFPtpz reporter mouse line during odontoblast differentiation, reparative dentinogenesis, and bone. In the developing teeth, BSP-GFPtpz was expressed at high levels in cementoblasts but not in odontoblasts or dentin. In bones, the transgene was highly expressed in osteoblasts at an early stage of differentiation. Interestingly, despite its lack of expression in odontoblasts and dental pulp during tooth development, the BSP-GFPtpz transgene was detected during in vitro mineralization of primary pulp cultures and during reparative dentinogenesis following pulp exposures. Importantly, under these experimental contexts, the expression of BSP-GFPtpz was still exclusive to DSPP-Cerulean, an odontoblast-specific reporter gene. This suggests that the combinatorial use of BSP-GFPtpz and DSPP-Cerulean can be a valuable experimental tool to distinguish osteogenic from dentinogenic cells, thereby providing an avenue to investigate mechanisms that distinctly regulate the lineage progression of progenitors into odontoblasts versus osteoblasts.

Human pulp response to conventional and resin-modified glass ionomer cements applied in very deep cavities

OBJECTIVES

This study assessed the human pulp response after adhesive restoration of cavities by indirect pulp capping with a conventional or a resin-modified glass ionomer cement.

MATERIALS AND METHODS

Deep cavities prepared in 26 human premolars were lined with Riva Light Cure (Riva LC), Riva Self Cure (Riva SC), or Dycal, and then restored with composite resin. Four teeth were used as intact control. After time intervals of 7 or 30 days, the teeth were extracted, processed for histological evaluation of the pulp, and the remaining dentin thickness (RDT) between the cavity floor and the pulp was measured.

RESULTS

At 7 days, a slight pulp inflammation associated with discrete tissue disorganization was observed in most of t the teeth lined with Riva LC and Riva SC. Moderate pulp inflammation occurred in one tooth lined with Riva LC. Bacteria were identified in one specimen of the same group that exhibited no pulp damage. At 30 days, slight pulp inflammation and discrete tissue disorganization persisted in two specimens treated with Riva LC, in which a thin layer of tertiary dentin was deposited. Mean RDTs ranged from 383.0 to 447.8 μm.

CONCLUSIONS

Riva LC produced more damage to the pulp than Riva SC. However, the initial pulp damage decreased over time and after 30 days both GICs were labeled as biocompatible.

CLINICAL RELEVANCE

In this study conducted with human teeth, the conventional and the resin-modified glass ionomer cements investigated were shown not to cause post-operative sensitivity or persistent pulp damage when applied as liners in very deep cavities, thereby indicating their biocompatibility.

[An experimental study of simvastatin-collagen composite sponge as a direct pulp capping material in rat molars]

OBJECTIVE

To assess the feasibility and efficacy of simvastatin-collagen composite sponge as a novel, direct pulp capping material.

METHODS

A total of 120 Sprague-Dawley rats were randomly divided into three groups: the simvastatin-collagen composite sponge group (SIM group), the collagen sponge group (CS group), and the Ca(OH)2 group (CH group). An endodontic entry cavity was prepared on the occlusion of the first molar on the left maxillary of each rat. The contralateral teeth were utilized as the normal control group. The rats were experimented after 1, 3, 7, 14, and 28 days. X-ray observations were conducted and the specimens underwent hematoxylin-eosin (HE) and Masson's Thichrome staining. Dentin bridge formations and pulpal biology reactions were evaluated histopathologically.

RESULTS

X-ray results: high-density images could be observed on the pulp exposure sites in the CH group on the 28th day. In the SIM group, high-density images could be observed after 14 and 28 days, whereas in the CS group, high-density images were not observable in the exposed area. HE and Masson's Thichrome staining results: different degrees of inflammation under the cavity were detected in the three groups at different time points. The inflammatory reaction of the CS group was the most serious. The degree of the inflammatory reaction varied significantly between the SIM and the CS groups on the 14th and 28th days (P<0.01). The inflammatory reaction in the SIM group was lighter than in the CH group. There was a statistical difference between the SIM and the CH groups on the 14th day (P<0.05). During the observation period, the SIM group induced the best and fastest formation of reparative dentin. As for dentin bridge formation, a significantly higher complete bridge rate was observed in the SIM group than in the CH and in the CS groups on the 14th day (P<0.05) and for the SIM and the CH groups compared with the CS group on the 28th day (P<0.05).

CONCLUSIONS

The simvastatin-collagen composite sponge exhibited satisfactory biocompatibility with the pulp tissue and promoted the formation of reparative dentin. The application of simvastatin-collagen composite sponge as a pulp-capping material has satisfactory potential.

Clinical and Histological Study on Direct Pulp Capping With CO2 Laser Irradiation in Human Teeth

The study aimed to histologically evaluate wound healing of exposed human pulp on direct pulp capping using super-pulsed CO₂ laser preirradiation. In this single-blind clinical trial, 28 third molar teeth of 17 volunteers were randomly capped with either CO₂ laser irradiation (n=14) or Dycal (calcium hydroxide cement; n=14) and restored using resin composite. The laser was operated in super-pulsed mode (pulse duration, 0.2 ms; interval, 5.8 ms; 0.003 J/pulse). The irradiation conditions were a power output of 0.5 W, an irradiation time of 15 seconds, repeat mode (10-ms irradiation and 10-ms intervals, for a total beam exposure time of 7.5 seconds), total applied energy of 3.75 J, and an activated air-cooling system. Each tooth was extracted at six or 12 months posttreatment and prepared for histological evaluation. We evaluated the parameters of pulp tissue disorganization, inflammatory cell infiltration, reparative dentin formation (RDF), and bacterial penetration. There were no significant differences between groups for all parameters at each postoperative period (Mann-Whitney U-test, p>0.05). CO₂ laser irradiation completely controlled bleeding and exudate from the exposed pulp. The CO₂ laser group had a tendency to delay RDF compared with the Dycal group, but 4 of 7 teeth from the CO₂ laser group showed a complete dentin bridge at 12 months posttreatment.

Assessment of Root Caries Lesion Activity and Its Histopathological Features

Despite certain similarities in the etiology of root caries (RC) and coronal caries, there are notable differences in their histology, namely with regard to the demineralization process, which should be taken into consideration when assessing lesion activity. In this chapter, we present the histological changes to the dentin and pulp, occurring physiologically or in response to caries lesions. We focus on the histological features specific to RC lesions, discussing the assessment of lesion activity. The physiological changes occurring to the dentin and pulp are the formation of secondary dentin and the sclerosis of dentin tubules, while tertiary dentin is formed during pathologic stimuli from caries lesions. Already in the early stages of active RC, the lesions seem softer, and bacteria are easily found within the dentin tubules. Inactive lesions, on the contrary, are characterized by fully remineralized tissue, with irregular mineral precipitation and containing ghost cells of microorganisms. Lesion activity is determined by observing their tactile sensation and their position with respect to the gingival margin.

[Wound healing effects of silk fibroin-bone morphogenetic protein-2 scaffolds on inflammatory pulp in rats]

OBJECTIVE

To identify the healing effect of electrospun silk fibroin-BMP-2 as a biologic pulp capping agent to inflammatory pulp in rat caused by lipopolysaccharide (LPS).

METHODS

A total of 30 healthy adult male Wistar rats were randomly divided into five groups:(1) normal control group without operation; (2) blank control group without capping agents; (3) calcium hydroxide capping group; (4) electrospun silk fibroin capping group; (5) electrospun silk fibroin-BMP-2 capping group. Bilateral upper first molars of each rat in group 2-5 were drilled to expose the pulp to LPS which was used to establish a model of inflammatory pulp. The exposed pulp was capped with different capping agents or without capping agents. Then the hole was sealed. The animals were sacrificed on days 3, 7, and 14 post-operation and histological analysis was carried out, including HE stain and CD14 immunohistochemical stain.

RESULTS

On day 7 and 14, the lowest inflammatory reaction score in HE stain among pulp capping groups was that of silk fibroin-BMP-2 group. The next were calcium hydroxide group and silk fibroin group. That of blank control group was the highest. The ranking of reparative dentine scores of those groups was just reversed. The D values of immunohistochemical stain of CD14 were not significantly different in groups applied pulp capping agents but significantly lower than blank control group on days 3 and 7. However, the D value of silk fibroin-BMP-2 group (0.145±0.011) was significantly lower than blank control group (0.287±0.019), calcium hydroxide group (0.170±0.017) and silk fibroin group (0.175±0.018) on day 14.

CONCLUSION

Electrospun silk fibroin compounded with BMP-2 promoted wound healing of exposed pulp and had better potential to stimulate formation of reparative dentine to establish a suitable environment for pulp recovery.

[Clinical research of EDTA pretreatment on the bonding strength of resin]

PURPOSE

This study was to evaluate clinical results of adhesives to sclerotic dentin in non-carious cervical lesions pretreated with ethylene diamine tetraacetic acid (EDTA).

METHODS

Twelve patients who had at least one pair of teeth with typical cervical wedge-shaped defects and class III sclerotic dentin were selected. The teeth were randomly divided into experimental and control groups. In the experimental group, EDTA was used to pretreat dentin surface first and then self-etching resin adhesive; In the control group, only self-etching resin adhesive was used. Modified USPHS rating system was applied in baseline, 6 months and 12 months after treatment. SAS 8.02 software package was used for two-sample rank sum test.

RESULTS

At the time point of 6-month and 12-month, the scores in the experimental group were significantly better than the control group (P<0.05).

CONCLUSIONS

EDTA pretreatment of the sclerotic dentin of cervical wedge-shaped defects could improve the resin bonding strength, marginal discoloration, marginal form and surface quality.

Reconstructing the life-time lead exposure in children using dentine in deciduous teeth

Data are presented to demonstrate that the circumpulpal dentine of deciduous teeth can be used to reconstruct a detailed record of childhood exposure to lead. By combining high spatial resolution laser ablation ICP-MS with dental histology, information was acquired on the concentration of lead in dentine from in utero to several years after birth, using a true time template of dentine growth. Time corrected lead analyses for pairs of deciduous molars confirmed that between-tooth variation for the same child was negligible and that meaningful exposure histories can be obtained from a single, multi-point ablation transect on longitudinal sections of individual teeth. For a laser beam of 100 μm diameter, the lead signal for each ablation point represented a time span of 42 days. Simultaneous analyses for Sr, Zn and Mg suggest that the incorporation of Pb into dentine (carbonated apatite) is most likely controlled by nanocrystal growth mechanisms. The study also highlights the importance of discriminating between primary and secondary dentine and the dangers of translating lead analyses into blood lead estimates without determining the age or duration of dentine sampled. Further work is in progress to validate deciduous teeth as blood lead biomarkers.

[The effect of 1,25(OH)D3 deficiency in the secondary dentin formation and mineralization and caries of the mice]

OBJECTIVE

To determine the role of 1,25(OH)2D3 on the secondary dentin formation and mineralization of the mice.

METHODS

The differences of the mandible mineralization between the wild-type and 1-alpha-hydroxylase gene knockout mice at 6 weeks old were assessed by hematoxylin-eosin (HE) staining, immunohistochemistry, alkaline phosphatase (ALP) histochemistry staining.

RESULTS

The ratio of caries were increased significantly, while the secondary dentin was reduced significantly, the deposition of type I collagen and osteocalcin on the secondary dentin of occlusion surface was decreased significantly, but the deposition of the Biglycan on the dentin was increased significantly, the active of ALP on the odontoblasts were reduced significantly in 1-alpha-hydroxylase gene knockout mice compared to that in the wild-type littermates.

CONCLUSION

1,25(OH)2D3 deficiency lead to a defect in the secondary dentin formation and mineralization and caries of the mice.

[Effects of Nd:YAG laser on micro-tensile bond strength of single bond adhesive system for non-carious sclerotic dentin]

OBJECTIVE

To investigate the effect of Nd:YAG laser on microtensile bond strength of single bond adhesive system for non-carious sclerotic dentin.

METHODS

Ten human molars with occlusal wearing were cut into equal halves (nearly 12 mm(2)), and randomly divided into experimental group and control group. The teeth in experimental group were processed with Nd:YAG laser (1 W, 10 Hz), and then applied with Scotchbond and filled with Z350 resin. In control group, the teeth were processed with single bond and filled with Z350 resin. The specimens were sectioned, and the microtensile bond strengths of each sample was tested by a universal testing machine.

RESULTS

The bond strength of the experimental group [(26.11 ± 1.62) MPa] was significantly higher than that of the control group [(22.27 ± 2.16) MPa], P < 0.05. Stero-microscope examination indicated that most of the fractures occurred in dentin-resin interface.

CONCLUSIONS

Nd:YAG laser can increase the microtensile bond strength of single bond adhesive system in non-carious sclerotic dentin.

[Observing interfacial nanoleakage in sclerotic dentin bonding under confocal laser scanning microscope]

OBJECTIVE

To observe sclerotic dentin bonding interfacial nanoleakage used total-etching system and self-etching system by confocal laser scanning microscope (CLSM).

METHODS

12 maxillary bicuspids with non-caries, natural cervical sclerotic lesions were divided into three groups. Artifically prepared wedge-shaped lesions were made in 12 sound maxillary bicuspids and divided into three groups as controls. Three kinds of dentin bonding agents, Single Bond (SB), Clearfil SE Bond (CB) and Xeno III (XB), were applied on the surface of the wedge-shaped lesion dentins according to the manufacturer' s instruction. The apical foramens were occluded with self-curing resin. Six specimen groups were individually exposed to 0.1% rhodamine B isothiocyanate in 50% alcohol solutions for 24 h. Then the teeth were section using slow saw and observed the specimens under CLSM.

RESULTS

Two-way ANVOA revealed significant influence of both type of the dentin substrate and the adhesive systems tested on the lengths of the dye-penetrated pathways, representing the amount of nanoleakage (P < 0.05). The lengths of the dye-penetrated pathways were longer in SB than in CB and XB, whatever in normal dentin or sclerotic dentin (P < 0.05). While the extension of nanoleakage were similar in CB and XB (P > 0.05). There was no statistical significance in the amount of nanoleakage in normal dentin and sclerotic dentin using SB (P = 0.148). In CB and XB, the amounts of nanoleakage in normal dentin were higher than in sclerotic dentin (P < 0.05).

CONCLUSION

The nanoleakage phenomena of bonding interface were observed in three bonding adhesives. In sclerotic dentin bonding interfaces, these nanoleakage phenomenon were located among resin and normal dentin as well as sclerotic dentin.

[Observation on bonding interface of sclerotic dentin with confocal laser scanning microscope]

OBJECTIVE

To observe the bonding interface of sclerotic dentin after treated with total-etching system and self-etching system by confocal laser scanning microscope (CLSM).

METHODS

A total of 12 maxillary bicuspids with non-caries, natural cervical sclerotic lesions were divided into three groups. The sclerotic dentin was bonded with Single Bond (SB, total-etching adhesive), Clearfil SE Bond (CB, two-step self-etching) and Xeno III (XB, one-step self-etching) according to the manufacturer's instruction. Artificially prepared wedge-shaped lesions made in sound maxillary bicuspids and bonded with same adhesive were used as control. The primer component was labeled with Rhodamine B Isothiocyanate. Hybrid layer and resin tag of dentin bonding interface were observed by CLSM.

RESULTS

Two-way ANVOA revealed significant influence of both the type of dentin and the bonding adhesive systems tested on resin tag and hybrid layer (P<0.05). Resin tag and hybrid layer in total-etching adhesive (SB) were longer and thicker than in self-etching adhesive (CB, XB) whatever in normal dentin or sclerotic dentin, while the resin tag and hybrid layer thickness were similar in two kind self-etching adhesive (P<0.05).

CONCLUSION

The resin rags were fewer and shorter and the hybrid layers were thinner in sclerotic dentin than in normal dentin. When bonding the same type dentin substrate, the resin rags were shorter and the hybrid layer thinner in used self-etching adhesive than total-etching.

[Histological evaluation of direct pulp capping with a self-etching adhesive and calcium hydroxide]

OBJECTIVE

To evaluate the beagles' pulp response following direct pulp capping with Clearfil SE BOND (SB).

METHODS

130 sound teeth were used. 120 had their pulps mechanically exposed and were divided in two groups. In group A, teeth were capped with SB. In group B, teeth were capped with calcium hydroxide (CH). The left 10 teeth were used as control. After 7, 30 and 90 days, the teeth were extracted and processed for light microscopical examination.

RESULTS

In 7 day observation period, inflammatory reaction in SB group was slighter than that of CH group, but the difference was statistical insignificant. In the 30 day and 90 day observation period, inflammatory reaction was slight in both groups, but specimens with dentin bridge formation was significantly less in SB group than in CH group (P < 0.05).

CONCLUSION

SB showed acceptable biocompatibility with pulp, but its ability to induce hard tissue barrier on pulp exposure is weaker than CH.

Retention of a resin-modified glass ionomer adhesive in non-carious cervical lesions. A 6-year follow-up

OBJECTIVES

The purpose of this study was to evaluate the clinical retention of a new resin-modified glass ionomer cement based adhesive combined with a hybrid resin composite or a poly-acid modified resin composite in non-carious cervical lesions during a 6-year period.

METHODS

The resin-modified glass ionomer adhesive (Fuji Bond LC), was placed in 73 cervical lesions, 36 with a universal hybrid resin composite (Tetric Ceram) and 37 with a poly-acid modified resin composite (Hytac). Fifty-one in lesions with sclerotic dentin and 22 in non-sclerotic ones. Of the sclerotic lesions 38 were slightly roughened with a diamond bur before conditioning. The restorations were evaluated with slightly modified USPHS criteria every six months during a 6-year period.

RESULTS

All except six restorations were evaluated during the 6 years. Twelve (17.9%) were lost, four Tetric Ceram (11.8%) and eight Hytac (24.2%) (p<0.05). Four were found in non-sclerotic lesions (20.0%) and eight in sclerotic lesions (17.0%). The differences between the sclerotic and non-sclerotic and the roughened and non-roughened lesions were not significant.

CONCLUSIONS

The resin-modified glass adhesive showed a superior clinical retention combined with the resin composite material, with an annual failure rate of 2%.

Durability of three simplified adhesive systems in Class V non-carious cervical dentin lesions

PURPOSE

To investigate the durability of three simplified systems in Class V non-carious abrasion/erosion lesions.

METHODS

144 non-carious cervical dentin lesions were restored either with Clearfil Liner Bond 2, a 2-step self-etching primer (n = 46), One Coat Bond, a one bottle total-etch system applied with one coat (n = 46), or Prompt-L-Pop, a 1-step self-etching primer ("all-in-one") (n = 52), in 90 individuals. Ninety-eight of the lesions showed sclerotic dentin and 46 were non-sclerotic. Sixty-one were slightly roughened with a diamond bur before conditioning. The restorations were evaluated every 6 months during a 2-year period with slightly modified USPHS criteria.

RESULTS

All except three restorations were evaluated over 2 years. The cumulative loss rates for Clearfil Liner Bond 2, One Coat Bond and Prompt-L-Pop were at 6 months: 4.3, 2.2 and 3.9%, at 18 months: 4.3, 10.9 and 15.4% and at 24 months: 8.7, 13.0 and 21.2%, respectively. The cumulative loss rates of the materials in sclerotic lesions (15.7%) versus non-sclerotic lesions (14.0%) were not significanty different. Restorations placed with a diamond bur-roughened lesions showed a loss rate of 14.5%, while for the non-roughened lesions the frequency was 14.8%.

Bonding to worn or fractured incisal edges: shear bond strength of new adhesive systems

OBJECTIVES

Resin composites can be proposed for the restoration of incisal edges. If a progressive wear or an old fracture is responsible for the loss of the incisal edge, the bonding substrate is likely to be sclerotic dentin, surrounded by enamel. The purpose of the study was to measure under laboratory conditions, the shear bond strength of three adhesive systems to the enamel and dentin exposed on the edge of incisors as a result of a long-time wear or an old fracture.

METHOD AND MATERIALS

Thirty extracted human incisors were selected. The teeth had to exhibit some exposed dentin on their edges, a result of old fractures or wear. The 30 specimens were randomly divided into three groups. In each group, a different adhesive system was tested for the ability to efficiently bond a resin composite restoration to the dental substrate. A three-step system (Scotchbond Multipurpose Plus), a one-bottle adhesive (Scotchbond 1), and a self-etching adhesive (Prompt-L-Pop) were compared. The shear bond strength of the restored samples was measured under a loading machine. The pattern of failure that each sample underwent as a result of loading was assessed under a stereomicroscope.

RESULTS

The highest values of bond strength were yielded by Scotchbond Multipurpose Plus (28.14 MPa), followed by Scotchbond 1 (16.15 MPa), and Prompt-L-Pop (9.26 MPa). These differences were statistically significant (P < .05). The most frequent pattern of failure was the combined adhesive-cohesive in resin fracture.

CONCLUSION

Adhesive systems involving phosphoric acid etching of the substrate were more dependable than a self-etch adhesive when bonding a resin composite restoration to worn or fractured incisal edges.

Resin adhesion to enamel and dentin: a review

This article reviews the current knowledge base regarding resin adhesion to enamel and dentin. A descriptive classification system for adhesive resin products as well as clinical considerations derived from the review are also presented to assist the clinician in the selection and application of these products.

Micro-tensile bond strengths to sclerotic dentin using a self-etching and a total-etching technique

OBJECTIVES

To evaluate the in vitro regional micro-tensile bond strengths of a self-etching/self-priming adhesive system to sclerotic dentin, in the absence or presence of phosphoric acid conditioning.

METHODS

Naturally-occurring, non-carious cervical lesions on extracted premolars were hand-cleaned with a slurry of pumice and chlorhexidine, then bonded without further cavity preparation. One group was bonded using Clearfil Liner Bond 2V (Kuraray Co. Ltd., Osaka, Japan). The other group was first conditioned with K-etchant; 40% phosphoric acid gel (Kuraray) prior to the application of the self-etching primer. Artificially prepared wedge-shaped cavities were also made in sound premolars and bonded with the two methods as controls. Resin composite build-ups were made using Clearfil Protect Liner F and AP-X resin composite (Kuraray). After storage in water for 24h, the teeth were sectioned into 0.7 x 0.7 mm composite-dentin beams along the occlusal and gingival walls, and at the apex of the lesions. The use of two conditioning methods, two substrate types, and three different locations yielded 10-14 beams for each of the 12 groups. After testing for the microTBS, representative beams that were stressed to failure were examined with SEM. Remaining fractured beams were demineralized and processed for TEM examination. Statistical analysis was performed using a three-way ANOVA and Student-Newman-Keuls tests.

RESULTS

Regardless of the conditioning methods, bond strengths to sound dentin were significantly higher than to sclerotic dentin (P< 0.05). With sclerotic dentin, there was no significant difference for the conditioning methods used, except that K-etchant significantly improved the bond strength at the gingival aspect of the lesions. Fractographic analysis revealed that the self-etching primer could not etch beyond the surface hypermineralized layer of sclerotic dentin. Interfacial failure occurred along the surface of the mineralized intermicrobial matrix and/or hypermineralized layer. With the use of phosphoric acid, a hybrid layer was only seen when the surface layers were thin. Incompletely removed sclerotic casts were evident in both groups.

SIGNIFICANCE

Removal of the surface layers of sclerotic dentin and/or conditioning with stronger acids may be beneficial to obtain stronger bonding to sclerotic dentin.

Clear cell odontogenic carcinoma with ghost cells and inductive dentin formation - report of a case in the mandible

An atypical case of clear cell odontogenic carcinoma occurred in the mandible of a 50-year-old Japanese man. Microscopically, the tumor mainly consisted of clear, glycogen-rich epithelial cell nests, aggressively proliferated in the mandible and invading into the surrounding soft tissues. Within the tumor cell nests, clusters of ghost cells were observed in addition to occasional foci of microcystic degeneration. Hyaline, osteoid or dentinoid-like deposits were also demonstrated adjacent to the tumor cell nests. Dentinal tubules were clearly revealed in some of these structures. Hence, this tumor was regarded as an epithelial neoplasm with odontogenic ectomesenchyme induction.

Hydroxyapatite applied as direct pulp capping medicine substitutes for osteodentin

Tissue changes in rat incisors after direct pulp capping with hydroxyapatite (OH-AP) have been investigated using light and electron microscopy. Immediately after direct pulp capping, necrotic cells and cell debris were scattered only in the superficial zone of an exposed site. At day 1, both neutrophils having many vacuoles and macrophages phagocytizing numerous OH-AP granules appeared in the lower part of the OH-AP layer. At day 3, the cells surrounding the basal part of the OH-AP layer had large nuclei and well-developed rough-surfaced endoplasmic reticulum. At day 5, the newly formed mineralized tissue consisting of needle-like crystals was observed directly adjacent to the deepest zone of the OH-AP layer. However, fibroblast-like cells phagocytosing applied OH-AP granules were seen even at this period. These findings suggest that the applied OH-AP could directly substitute for osteodentin.

Biocompatibility of Clearfil Liner Bond 2 and Clearfil AP-X system on nonexposed and exposed primate teeth

OBJECTIVE

Recent studies have demonstrated that acid etching of vital dentin and pulpal tissue does not retard pulpal healing, odontoblastoid cell differentiation, or dentinal bridge formation when the pulp is capped with adhesive resins. The purpose of this study was to evaluate the pulpal response in nonexposed and exposed monkey pulps to treatment with the Clearfil Liner Bond 2 and Clearfil AP-X system.

METHOD AND MATERIALS

Class V and Class I cavities in nonexposed and exposed pulps were observed at 7 or 8, 27, and 97 days.

RESULTS

There were no differences in pulpal inflammation between the Clearfil Liner Bond 2/Clearfil AP-X specimens and calcium hydroxide controls in either Class V or Class I cavities at the various time periods.

CONCLUSION

Clearfil Liner Bond 2 and Clearfil AP-X system is not toxic to either nonexposed or exposed pulpal tissues when placed according to manufacturer's directions.

Defense responses of dentin/pulp complex to experimentally induced caries in rat molars: an immunohistochemical study on kinetics of pulpal Ia antigen-expressing cells and macrophages

Experimental caries was induced in rats that were inoculated orally with Streptococcus mutants and maintained on a cariogenic diet. During the caries process, kinetics of the pulpal la antigen-expressing cells and macrophages was monitored immunohistochemically and was correlated with caries depth and the status of reparative dentin formation. Initial pulpal response was characterized by a localized accumulation of la antigen-expressing cells beneath the dentinal tubules communicating with the superficial caries. This was followed by a caries-depth related increase of la antigen-expressing cells and macrophages in the coronal pulp. The accumulation of these cells under the dentin was most apparent when the caries had progressed into the reparative dentin. These findings suggest that the response of la antigen-expressing cells to carious irritants triggers the defense reactions of the pulp. The intensity of the defense reactions may be correlated with the permeability of carious dentin.

Dental complications associated with repeated orotracheal intubation in infancy: a case report

Various oral and dental problems have been attributed to orotracheal intubation in the neonatal period. A case is described of a child whose dental anomalies are ascribed to multiple orotracheal intubations for the management of a complex cardiac abnormality. Six intubations were required between the ages of 9 days and 4 years for investigation and surgery. His maxillary right primary central incisor did not erupt until 3 years of age and the maxillary left was still unerupted at 6 years and 10 months and was rotated in its crypt. At this time, the mandibular primary incisors were physiologically mobile but the maxillary right primary central incisor remained firm. Both maxillary primary central incisors were extracted and examined histologically and showed abnormal morphology, enamel hypoplasia, and disordered dentine formation and root resorption. Subsequent eruption of the left permanent central incisor revealed hypoplasia of its incisal edge. It is suggested that the delayed eruption and abnormal morphology of the primary incisors were due to pressure effects on the overlying mucosa, follicular displacement and localized trauma caused by intubation. This case highlights the importance of monitoring the developing dentition of patients with a history of orotracheal intubation, so that interceptive treatment may be instituted when appropriate.

[Porcelain onlays]

This article covers the clinical application of feldspathic porcelain onlays. The indication, tooth preparation, try-in and cementation procedures using total etching and the latest concepts in dentin bonding are discussed. When properly executed fired porcelain onlays can meet the highest esthetic demands but they require maximum skills, both of the dental surgeon and of the dental technician.

Histo-pathological study of a glass-ionomer/resin (Geristore) restoration system

The purpose of this experiment was to investigate histo-pathologically the pulpal reaction to a glass-ionomer/resin (Geristore) restoration system in human teeth. Black's class I cavities were prepared in 22 human teeth; these were divided into 2 groups, one with the Geristore after cavity was cleaned with 10% NaOCl solution and 3% H2O2 solution (Group G) and the other with the Geristore after the cavity was applied with Mirage-Bond (Group MG). The treated teeth were observed clinically over 90 days after operation. They were then extracted for histological examination. No unpleasant symptoms were noted. A few pathological changes were observed. No histo-pathological score differences were observed between groups G and MG. The average evaluation score of pathological results in both groups G and MG were excellent. Microorganisms observed in the cavity dentin of the group G was fewer than in group MG. In some cases, microorganisms were observed along the dentin walls. In conclusion, the pulpal injury due to this Geristore restoration system was slight, and the system was considered to be safe for the pulp and clinically useful.

Effect of root canal status on periodontal healing after surgical injury in dogs

This study was carried out to observe if the status of the root canal might influence the healing process of surgically prepared experimental periodontal lesions. Forty tooth roots from four dogs were divided into four different groups: a) root canals with vital pulps, b) root canals open to the oral environment, c) root canals infected and filled with zinc oxide eugenol cement, and d) root canals infected and filled with calcium hydroxide. By means of a surgical intervention, a cavity was prepared in the medium portion of the roots. Six months later, the specimens were removed and prepared for histological analysis. The results, which were submitted to statistical analysis, showed that the status of the root canals influenced the healing process of the experimental periodontal lesions. In the groups where the root canals were filled, calcium hydroxide gave the best results. In the group with root canals left open to the oral environment, resorption of the dentin of the experimental cavities, was the most obvious observation. However, it did not prevent the repair process, only slowed it down.

Pulpal response to adhesive resin systems applied to acid-etched vital dentin: damp versus dry primer application

A number of studies have reported that acid etching of dentin is toxic to the cells of the odontoblastic layer and dental pulp. Other studies report that pulpal inflammation is a consequence of bacterial microleakage. The purpose of this study was to observe the degree of pulpal healing after pretreatment of vital dentin prior to placement of All-Bond and Scotch-bond 2 composite resin adhesives. Zinc oxide-eugenol cement and an acidic cement were employed as controls. One hundred twelve Class V nonexposed cavity preparations were placed throughout the dentitions of five healthy adult rhesus monkeys and observed at 3, 25, and 80 days. Various dentinal pretreatment procedures were employed. The All-Bond Universal primer system was placed on air-dried vital dentin in 23 cavities and on damp vital dentin in 27 cavities. Scotchbond 2 was placed as per manufacturer's instructions. All treatment procedures, materials, and times were represented in all animals. Placement of silicate cement resulted in the most severe pulpal responses at all time periods. Stained bacterial profiles in the remaining dentin on the axial walls of inflamed control pulps were associated with severe pulpal inflammation. These results indicate that acid etching of vital dentin does not impair pulpal healing in deep Class V cavities.

Pulpal response to a new light-activated fluoride releasing liner

The purpose of this study was to investigate the degree of pulp irritation of a newly developed light-activated fluoride-releasing adhesive resin liner using canine teeth compared to the amount caused by a negative control, zinc oxide eugenol cement (ZOE), and a positive control, silicate cement (silicate). In the cases of unexposed pulp, this experimental liner showed none, slight or moderate pulpal changes at 3 d postoperatively. At 30 and 90 d, no pulpal response to the experimental liner was detected in almost all cases. These findings were similar to the ZOE and better than the silicate. There was less evidence of pulpal irritation produced by the experimental liner. This material seems to be safe to the pulp under the conditions of this study.

Chronic focal sclerosing osteomyelitis associated with a cracked tooth. Report of a case

Chronic focal sclerosing osteomyelitis is a periapical lesion that involves reactive osteogenesis evoked by chronic inflammation of the dental pulp. In most cases, this lesion develops in the mandibular molar region in response to a low-grade infection of the pulp that results from a deep carious lesion. A case is presented in which incomplete tooth fracture was the apparent cause of this type of periapical pathosis.

Effect on human teeth of renal transplantation: a postmortem study

Extracted teeth from five deceased patients treated by renal transplantation were examined radiographically and histologically, and compared with teeth from healthy persons of approximately the same age. In three of the patients with a renal transplant, the radiographs showed normal pulp chamber sizes, but histologic examination revealed a widened predentin zone, approximately four times greater than in the controls. In two of the patients the radiographs showed marked reduction of the pulp chamber size. The histologic changes of these teeth were mainly an extensive amount of secondary dentin along the pulp chamber walls and the root canals, with a markedly reduced pulp space. One explanation for the difference between the patients was that patients with extensive pulp calcifications were given a higher total amount of corticosteroids than patients with a widened predentin zone.

A new method for dental age estimation in adults

Several statistical methods have been proposed for estimation of age from teeth in human adults. Due to the smallness of the material or statistical shortcomings in previous reports, improvements of the methods were desirable and seemed possible. As a contribution to such improvement various age-related changes have been studied in a material of 1000 teeth. For each type of change the kind of measurement most strongly related to age was chosen, and a multiple regression analysis was run with age as the dependent variable, using SPSS/PC+ statistical program. Statistically significant formulae were calculated for each type of tooth excluding molars. Because the sex of a deceased body may be unknown and the tooth colour influenced by changes after death, separate formulae excluding these factors were calculated. For the calculated formulae the Pearson correlation (tau) varied from 0.76 in mandibular second premolars (SEX and COLOUR excluded), to 0.91 for maxillary central incisors; a rather promising result compared with other methods. In addition, the intercorrelations between the age-related factors were calculated after control for the effect of age. In some types of teeth, but not in all, some of the factors displayed significant intercorrelation. To compare these formulae with previous methods an unbiased test in another independent material is needed.

Early cellular events in an actinomycin D-created dentin niche in the rat incisor

Administration of actinomycin D at a dose level of 0.375 microgram/g resulted in the selective disruption of developing odontoblasts at a critical stage of morphogenesis. A dentin niche was formed which was later repaired by cellular reparative dentin. The cellular changes which resulted in dentin niche formation were studied histologically and ultrastructurally in serial longitudinal and transverse sections from tissues obtained 10 h to 80 h following injection of the drug. Five stages were identified: initial destruction (10-20 h), rapid destruction (30-40 h), debris removal (50-60 h), proliferation (60-80 h) and matrix deposition (post 80 h). The cellular changes found in the dental papilla were considerably different from those found in inflammation, resolution and repair of fibrous connective tissue. These early stages were dominated by apoptosis and heterophagy, and after 80 h by disordered dentin matrix formation. The three-dimensional morphology of the defect was reconstructed from serial sections. The shape of the niche was the result of interference by actinomycin D in the patterns of proliferation and migration of the cells in the apical region of the rat incisor tooth.

The effect of lasers on dental hard tissues

There is a quest to find a method to remove diseased and healthy dental hard tissues without the negative stimuli associated with dental handpieces. Today, lasers are being considered as a potential replacement. This report evaluates effects of three lasers on dentin and pulpal tissues. The Er:YAG laser appears to have a lesser thermal effect.

Histomorphometric study of dental pulp during orthodontic tooth movement

Orthodontic tooth movement has been implicated in secondary changes to the dental pulp. The purpose of this study was to correlate the effects of orthodontic tooth movement on the dental pulp by histomorphometric parameters. Four groups, each consisting of 36 male adult Sprague-Dawley strain rats, were studied with differing force magnitudes. These included a sham group in addition to groups with bilaterally placed appliances activated to 20, 40, and 60 g of initial force designed to mesially tip the maxillary first molars. Six rats were killed at 1, 3, 5, 7, 10, and 14 days. Specimens were fixed, embedded, and stained with tetrachrome. Pulpal measurements were made with an image analyzer and included changes in predentin and vascularity. Findings indicated a significant increase (p < or = 0.05) relative to time and force magnitude in capillary number. An initial pulpal hyperemia was observed following activation of orthodontic force which was unrelated to force magnitude. A force-dependent increase in predentin width was measured at the peak of the tooth movement cycle.