Combined effects of calcium hydroxide and photobiomodulation therapy on apexogenesis of immature permanent teeth in dogs.

Treatment of high-risk traumatic immature teeth due to incomplete root development is challenging. Apexogenesis is currently the ideal treatment option that allows normal root development. The purpose of this study was to evaluate the apexogenesis process of immature permanent teeth of dogs when co-administered with calcium hydroxide and photobiomodulation therapy (PBMT). A total of 36 immature permanent anterior and premolar teeth were selected from three 4-6-month-old dogs of Iranian mixed generation. The teeth were categorized into two groups, calcium hydroxide with laser irradiation (CHL) and calcium hydroxide without laser irradiation (CH). All the selected teeth received calcium hydroxide pulpotomy. After restoring teeth with amalgam, the CHL group received gallium­aluminum-arsenide (GaAlAs) diode laser (810 nm, 4.2 J/cm2, 0.3 W, 9 s,CW) on apical one-third of both buccal and lingual roots. The irradiation was repeated every 48 h for fourteen days. Intravenous tetracycline was used to observe newly formed dentin in the first, third, seventh, and fourteenth days. The distance between tetracycline lines (DTL) was examined by Fluorescence microscopy. Generalized estimating equations (GEE) were used for data analysis. In all assessments, the mean DTL were greater in the CHL group. However, the two groups had no significant differences in the amount of deposited dentin between the first and third, third and seventh, and first and seventh lines. Meanwhile, there was a significant difference between the two groups in terms of the distances between lines 7 and 14, 1 and 14 and also 3 to 14 (P < .001). In other words, from the 7th day onwards, there was a significant difference between the two groups. Within the limitation of this study, the combination therapy of PBMT and pulpotomy with calcium hydroxide accelerated apexogenesis in immature permanent dogs' teeth.

Microtensile Bond Strength of Resin-Modified Glass Ionomer Cement to Sound and Artificial Caries-Affected Root Dentin With Different Conditioning.

In this laboratory study, the microtensile bond strengths (µTBS) of resin-modified glass ionomer cement (RM-GIC) to sound and artificial caries-affected bovine root dentin (ACAD) using three different conditioning agents were evaluated after 24 hours and three months. The fractured interface was examined with a scanning electron microscope (SEM). Specimens were created on bovine root dentin that was embedded in epoxy resin. For the ACAD specimens, artificial carious lesions were created. The RM-GIC (Fuji II LC) was applied either directly (no treatment), after application of self conditioner, cavity conditioner, or 17% ethylenediamine tetraacetic acid (EDTA) applied for 60 seconds, on sound dentin and ACAD, then light cured. They were stored in artificial saliva for 24 hours or three months. Following this, the specimens were cut into sticks for the µTBS test, and the failure mode of the debonded specimens was examined by using SEM. Pretest failures were excluded from the statistical analysis of the µTBS values because of their high incidence in some groups. Results showed that the µTBS values were significantly affected by the dentin substrate as well as the conditioning agent. Self conditioner provided the highest and most stable µTBS values, while cavity conditioner showed stable µTBS values on sound dentin. Both self conditioner and cavity conditioner had significantly higher µTBS values than the no treatment groups. EDTA conditioning reduced the µTBS after three months to sound dentin, while it showed 100% pretest failure with ACAD for both storage periods.

Metrical and histological investigation of the effects of low-level laser therapy on orthodontic tooth movement.

The aim of this study was to evaluate the effects of 820-nm diode laser on osteoclastic and osteoblastic cell proliferation-activity and RANKL/OPG release during orthodontic tooth movement. Thirty-eight albino Wistar rats were used for this experiment. Maxillary incisors of the subjects were moved orthodontically by a helical spring with force of 20 g. An 820-nm Ga-Al-As diode laser with an output power of 100 mW and a fiber probe with spot size of 2 mm in diameter were used for laser treatment and irradiations were performed on 5 points at the distal side of the tooth root on the first, second, and 3rd days of the experiment. Total laser energy of 54 J (100 mW, 3.18 W/cm(2), 1717.2 J/cm(2)) was applied to group II and a total of 15 J (100 mW, 3.18 W/cm(2), 477 J/cm(2)) to group III. The experiment lasted for 8 days. The number of osteoclasts, osteoblasts, inflammatory cells and capillaries, and new bone formation were evaluated histologically. Besides immunohistochemical staining of PCNA, RANKL and OPG were also performed. No statistical difference was found for the amount of tooth movement in between the control and study groups (p > 0.05). The number of osteoclasts, osteoblasts, inflammatory cells, capillary vascularization, and new bone formation were found to be increased significantly in group II (p < 0.05). Immunohistochemical staining findings showed that RANKL immunoreactivity was stronger in group II than in the other groups. As to OPG immunoreactivity, no difference was found between the groups. Immunohistochemical parameters were higher in group III than in group I, while both were lower than group II. On the basis of these findings, low-level laser irradiation accelerates the bone remodeling process by stimulating osteoblastic and osteoclastic cell proliferation and function during orthodontic tooth movement.

Effect of photobiomodulation on vinblastine-poisoned murine HERS cells.

OBJECTIVE: The aim of this study was to investigate the effect of near-infrared (NIR) photobiomodulation on the proliferation and glutathione levels in murine Hertwig's epithelial root sheath (HERS) cells after poisoning with vinblastine. BACKGROUND: Photobiomodulation has been shown to improve wound healing in a number of animal models. There have been no studies on the effect of photobiomodulation on cancer-related chemotherapy injury to the cells that initiate tooth root growth. MATERIALS AND METHODS: Control groups consisted of murine HERS cells without vinblastine (VB-) and cells with vinblastine at 10, 20, and 30 ng/mL (VB10, VB20, and VB30). Experimental groups consisted of these same groups with light therapy (VB-L, VB10L, VB20L, and VB30L). The cells were exposed to vinblastine for 1 h. Photobiomodulation consisted of a 75-cm(2) gallium-aluminum-arsenide light-emitting diode (LED) array at an energy density of 12.8 J/cm(2), delivered with 50 mW/cm(2) power over 256 s. RESULTS: Vinblastine alone significantly decreased HERS cell proliferation and glutathione levels at all concentrations (VB10 [-55%, p < 1.0 × 10(-8)]; VB20 [-72%, p < 1.0 × 10(-9)]; VB30 [-80%, p < 1.0 × 10(-10)]; and VB10 [-36%, p < 0.0001]; VB20 [-49%, p < 1.0 × 10(-6)]; VB30 [-53%, p < 1.0 × 10(-7)] respectively). Photobiomodulation significantly increased cell proliferation at all levels of vinblastine exposure (VB10L [+50%, p < 0.0001]; VB20L [+45%, p < 0.05]; VB30 [+39%, p < 0.05]) but not of the control (+22%, p = 0.063). The photobiomodulation significantly increased glutathione production in all concentrations of vinblastine except 20 ng/mL (VB10L [+39%, p = 0.007]; VB20L [+19%, p = 0.087]; VB30 [+14%, p = 0.025]) and the control (+12%, p = 0.13). CONCLUSIONS: Photobiomodulation demonstrated an improvement in proliferation and glutathione levels in vinblastine-poisoned murine HERS cells.

Influence of the angle of irradiation of the Er,Cr:YSGG laser on the morphology, attachment of blood components, roughness, and root wear: in vitro study.

BACKGROUND AND OBJECTIVES: To evaluate the influence of the working tip angulation of the Er,Cr:YSGG laser on the morphology, attachment of blood components, roughness, and wear on irradiated root surfaces compared to scaling and root planing (SRP). STUDY DESIGN/MATERIALS AND METHODS: The present study used 45 teeth, of which 25 were used for the analysis of the morphology and the attachment of blood components and 20 were used for the analysis of the roughness and of the root wear. The teeth were randomly divided into five groups according to the treatment applied: (G1) Laser Er,Cr:YSGG-30°; (G2) Laser Er,Cr:YSGG-45°; (G3) Laser Er,Cr:YSGG-60°; (G4) Laser Er,Cr:YSGG-90°; and (G5) SRP. RESULTS: The root surfaces irradiated with the Er,Cr:YSGG laser working angulation tip of 45° and 60°, and the samples scaled with manual instruments presented greater attachment of blood components than the group where the Er,Cr:YSGG laser irradiated at working tip angulation of 30° and 90° (P<0.05). The samples irradiated with the Er,Cr:YSGG laser were rougher than the samples scaled with manual instruments (P<0.05). The group that was irradiated with the Er,Cr:YSGG laser at an angle of 30° presented the least wear in comparison to all the other treatments (P<0.01). CONCLUSIONS: The irradiated root surfaces proved to be rougher than those scaled with manual instruments; however, irradiation at working tip angulations of 45° and 60° produced results of attachment of blood components and root wear comparable with those obtained with manual instrumentation.

[Effect of Galla Chinesis on the demineralization of dental root tissue in pH cycling model].

OBJECTIVE: To evaluate the anti-demineralization efficacy of Galla Chinesis in pH cycling model for elucidating the anti-root caries mechanism. METHOD: Anti-demineralization efficacy evaluation of the natural medicine in the pH-cycling models was used . Sound human root blocks were pH-cycled through the treatment solution, acidic buffer and neutral buffer. The cycling times for demineralization study were 12 times, 2 times per day. The acidic buffers were retained for calcium analysis by atomic adsorption spectroscopy. The sections of blocks were analysed after pH-cycling by CLSM. Treatments were 4 g x L(-1). Galla Chinesis, 1 g x L(-1) NaF solution and distilled water. RESULT: Galla Chinesis was found to inhibit the demineralization in the pH cycling model. Although the effect was not as good as fluoride, there was no significant difference between the two groups. CONCLUSION: These data suggest that Galla Chinesis could modulate the mineralisation behaviour of root tissue in a defined chemical circumstance. These findings support the proposition that Galla Chinesis may be a promising anticaries natural medicine in the future.

Micromorphological and micronanalytical characterization of stagnating and progressing root caries lesions.

Root caries is the predominant disease of the tooth tissues in the elderly population and differs in progression and micromorphology from coronal dentin caries. Therefore, different clinical concepts are needed for the treatment of these progressing and arrested lesions. It was the aim of this study to investigate the three-dimensional structure and volume of stagnating and progressing root caries lesions and to determine the mineral composition of the different lesion zones to achieve a better understanding of the natural history of root caries lesion formation. Of 21 extracted human teeth of patients between 42 and 77 years of age with stagnating and progressing root caries lesions serial sections were cut and investigated with polarized light and scanning electron microscopy. From the polarized light micrographs 3D reconstructions were made to determine the volumes of the lesion zones and their relations expressed in a demineralization index (DI). With increasing size of the demineralizing zone the DI increased indicating an increase in the size of the translucent zone. The 3D reconstructions showed distinct differences between stagnating and progressing root caries lesions. In the hypermineralized translucent dentin not all dentin tubules were obliterated by intratubular dentin and within the translucent dentin scattered dead tracts were found. Electron dispersive X-ray (EDX) analysis showed that the intertubular dentin of the translucent dentin was also demineralized to a certain extent. The results indicate distinct morphological differences between progressing and stagnating root caries lesions which may have consequences for treatment strategies.

Spatial distribution of lead in the roots of human primary teeth.

Lead remains one of the most hazardous metals in our environment. The concentrations of lead in coronal dentine and enamel have previously been reported but limited information is available regarding lead levels in radicular dentine and cementum. This study reports the distribution of lead in 26 roots of 16 human maxillary primary teeth from seven individuals. In addition, calcium and phosphorous concentrations were also measured to detect any variations in the degree of mineralization in different regions of the roots. The mean lead concentration in these roots was 1.67 +/- 1.43 microg/g, which is comparable to other studies. In all cases there were higher lead concentrations in the apices of non-resorbed roots of primary maxillary teeth relative to middle and cervical regions. The findings reported here are of potential significance during the process of physiological root resorption whence periapical tissue may be exposed to higher levels of lead.

Periodontal regeneration in a buccal dehiscence model in monkeys after application of enamel matrix proteins.

There is increasing evidence that cells of the epithelial root sheath synthesize enamel matrix proteins and that these proteins play a fundamental role in the formation of acellular cementum, the key tissue in the development of a functional periodontium. The purpose of the present study was to explore the effect of locally applied enamel matrix and different protein fractions of the matrix on periodontal regeneration in a buccal dehiscence model in monkeys. Buccal, mucoperiosteal flaps were raised from the canine to the 1st molar on each side of the maxilla. The buccal alveolar bone plate, the exposed periodontal ligament and cementum were removed. Various preparations of porcine enamel matrix with or without vehicles were applied before the flaps were repositioned and sutured. After 8 weeks, the healing was evaluated in the light microscope, and morphometric comparisons were made. Application of homogenized enamel matrix or an acidic extract of the matrix containing the hydrophobic, low molecular weight proteins, amelogenins, resulted in an almost complete regeneration of acellular cementum, firmly attached to the dentin and with collagenous fibers extending over to newly formed alveolar bone. After application of fractions obtained by neutral EDTA extraction containing the acidic, high molecular weight proteins of the enamel matrix, very little new cementum was formed and hardly any new bone. The results of the controls in which no test substance was applied before the repositioning of the flap, were very similar to those obtained with the EDTA extracted material. Propylene glycol alginate (PGA), hydroxyethyl cellulose and dextran were tried as vehicles for the enamel matrix preparations. Only PGA in combination with the amelogenin fraction resulted in significant regeneration of the periodontal tissues.

Electron microprobe analysis in periodontal guided tissue regeneration.

Electron microprobe analysis was used to determine the evolution of Ca, P and S in regenerated tissue surrounding incisors roots after periodontal treatment with guided tissue regeneration. Our results, which showed increased Ca and P, and decreased S are discussed in relation to the process of mineralization electron probe microanalysis with potentially provided an accurate means of assessing the degree of mineralization in extremely small tissue samples.

[Escape of hydrogen peroxide and oxygen from the root canal]. / Untersuchungen zum Austritt von Wasserstoffperoxid und Sauerstoff aus dem Wurzelkanal.

In vitro investigations demonstrate that hydrogen peroxide, like the oxygen emitted from the root canal, escapes into the area around the root. The amount measurable was dependent on the concentration, the amount of time that the hydrogen peroxide was left in the root canal and the patency of the foramen apicale. The growth of the Staphylococcus aureus (SG 511) was restricted in the area around those roots whose root canal contained a 5% solution of hydrogen peroxide.

Microradiography of experimental root surface caries in man.

The aim of this study was to describe the pattern and rate of mineral loss during experimental root surface caries in situ without giving frequent sucrose rinses as a supplementary cariogenic challenge. Six elderly persons carried at total of 18 specimens of unerupted human root surface in recessions of lower partial dentures for 1, 2 and 3 months. Another six root surfaces served as controls. No cleaning of the specimens was allowed during the experimental period whereas the natural dentition was cleaned with a nonfluoride toothpaste. All the specimens, as observed by quantitative microradiography, exhibited subsurface caries lesions. Despite variation between individuals the depth of subsurface demineralization increased linearly with time, the average depth of the lesions being 240 microns after 1 month and 630 microns after 3 months. Delta MC, calculated as the difference in total mineral content between control and test specimens throughout the lesions, increased linearly with time from 2,000 to 8,400 vol% microns after 1 and 3 months, respectively. Preparation for microradiography induced a certain shrinkage of the lesions which resulted in an underestimation of the actual loss of mineral. It is concluded that this experimental model is suitable for studying the etiology and prevention of root surface caries provided the interindividual variation is taken into account.

[Calcium and phosphorus content and the 45Ca incorporation into the bones and teeth of rats after a 22-day orbital space flight on board the "Cosmos-605" satellite ship]. / Soderzhanie kal'tsiia, fosfora i vkliuchenie 45Ca v kostiakh i zubakh krys posle 22-sutochnogo kosmicheskogo orbital'nogo poleta na korable-sputnike "Kosmos-605"

Examinations of 37 rats flow for 22 days onboard the biosatellite Cosmos-605 revealed no changes in the mineralization coefficient or the Ca and P content in humerus and teeth of the animals on the 2nd and 26th postflight days. Radioisotope studies showed changes in the specific activity of Ca45 incorporation in humerus and incisors. In flight rats the parameter decreased by 37-44%, in synchroneous animals it increased by 102% in bones and by 20% in incisors as compared with the vivarium controls on the 2nd postflight day. The specific activity of Ca45 incorporation was 92.7% in humerus and 44.2% in incisors of flight rats and 72.9% in humerus and 94.7% in incisors of synchroneous rats as compared with the vivarium controls on the 26th postflight day.

Root caries: distribution and uptake of elements in lesions adjacent to silicate or amalgam restorations.

In carious lesions adjacent to silicate or amalgam restorations outer lesions of the cementum showed the same content and distribution of Ca, P, Mg, and S as did primary lesions in this area, but differed from these in having an increased content of Zn, Al, and probably F (silicate cases) and Zn, Sn, and Cu (amalgam cases). The cementum walls showed an uptake of ions largely similar to that previously described in dentinal walls.