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At least 1,387 records · Page 77Linked to original sources
PubMed1998

Scanning electron microscopy and histologic analysis of an apexification "cap": a case report.

A maxillary permanent central incisor with a history of trauma, apexification, and internal thermocatalytic bleaching sustained a horizontal fracture at the cementoenamel junction, which necessitated extraction of the tooth. After removal, the root apex was examined histologically and by scanning electron microscopy. An apexification "cap" with unusual anatomic character and structure was observed.

Adult↗
PubMed2006

[External root resorption].

Root resorption may be a physiological (resorption of deciduous teeth) or a pathological process (resorption of permanent teeth). In the latter case an external and an internal form of resorption can be distinguished. Root resorption may occur on one tooth or on several teeth within a dentition and it may be caused by trauma, periodontitis, orthodontic treatment, internal bleaching, cysts, tumors, or by stimuli from a necrotic dental pulp. Current knowledge concerning the pathogenesis of root resorption and therapeutic approaches are presented. For cervical resorption, it is assumed that the stimulus for the resorbing cells originates from the bacteria within the gingival sulcus and along the affected root surface. The case presented here was initially diagnosed as chronic periodontitis of medium severity. Scaling and root planing were performed resulting in a significant improvement of the periodontal status. Two years later, following a period of irregular recall visits, the patient presented with large areas of cervical resorption on teeth 36 and 37 which made it impossible to preserve these teeth. After another six months, teeth 34 and 35 showed deep destruction caused by external root resorption, mandating the extraction of these teeth as well. Fourteen months later, external root resorptions were evident on teeth 32 and 33, and at the same time, a recurrence of the chronic periodontitis was noted. Periodontal therapy was performed under a systemic antibiotic regime. It was possible to preserve teeth 32 and 33 through surgical crown lengthening procedures. No additional resorption has been observed ever since.

Adult↗
PubMed2002

Fluoride uptake and development of artificial erosions in bleached and fluoridated enamel in vitro.

The aim of the present in vitro study was to evaluate the effect of carbamide peroxide (CP) bleaching on fluoride uptake in enamel. Additionally, the susceptibility for erosion in bleached and fluoridated enamel was tested. Each four enamel specimens were prepared from 44 bovine incisors. The four samples gained from each tooth were distributed among four groups (A-D) of 44 specimens each: A: (unbleached/unfluoridated) served for determination of baseline fluoride concentration; B: (unbleached/fluoridated) four times in 2000 ppm NaF solution (2 min); C: (bleached/unfluoridated) four times in 10% CP (8 h); D: (bleached/fluoridated) four times in 10% CP and fluoridation. In 22 specimens of each group both KOH-soluble and structurally bound fluoride were determined in the outermost 30 micro m of the enamel. In the remaining specimens erosions were induced by immersing the samples in 5 mL of 1% citric acid (20 min) and microhardness was evaluated before and after demineralization. Statistical analysis showed that KOH-soluble fluoride uptake was similar for group B and D specimens. Structurally bound fluoride uptake after fluoride application in unbleached samples was significantly higher than in bleached ones. Bleaching only resulted in a highly significant fluoride loss. In all samples erosion caused a significant microhardness loss. The study showed that pre-treatment of enamel with CP followed by fluoridation does not improve erosive resistance. Moreover the study reveals that CP treatment decreases concentration of structurally bound fluoride in enamel which could not be outweighed by fluoridation with 2000 ppm NaF. It is concluded that it is not feasible to improve fluoride uptake in enamel with a pre-treatment with 10% CP.

Analysis of Variance↗
PubMed2005

Use of bleach to eliminate contaminating DNA from the surface of bones and teeth.

The extraction of DNA from archaeological or forensic skeletal remains can provide quite powerful data for analysis, but is plagued by a unique set of methodological problems. One of the most important methodological problems to overcome in such analyses is the presence of modern contamination on the surfaces of bones and teeth, which can lead to false positives and erroneous results unless it is removed before DNA extraction is initiated. Ancient DNA (aDNA) researchers and forensic scientists have employed a number of techniques to minimize such contamination. One such technique is the use of bleach (sodium hypochlorite--NaOCl) to "destroy" contaminating DNA. However, a consensus on the optimum concentration of sodium hypochlorite to be used and the amount of time the bone or tooth should be exposed to it has not emerged. The present study systematically approaches the issue by introducing contamination to ancient bones (from approximately 500 BP) and determining which of several sodium hypochlorite treatments best eliminates surface contamination. The elimination of surface contamination from bone requires immersion in at least 3.0% (w/v) sodium hypochlorite (approximately equal parts of commercial bleach and water) for at least 15 min. Endogenous DNA proved to be quite stable to even extreme sodium hypochlorite treatments (6% for 21 h), suggesting that DNA adsorbs to hydroxyapatite in the bone and that this process facilitates the preservation of DNA in ancient skeletal remains.

DNA↗
PubMed1997

Enamel microabrasion: observations after 10 years.

Enamel microabrasion has become accepted as a conservative, nonrestorative method of improving the appearance of teeth with superficial dysmineralization and decalcification defects. This article reviews the technique of enamel microabrasion using a commercially available compound of hydrochloric acid and fine-grit silicon carbide particles in a water-soluble paste. It also describes a method of combining enamel microabrasion with carbamide peroxide home bleaching. Finally, it presents the cases of representative patients who underwent enamel microabrasion (alone or in combination with dental bleaching).

Adult↗
PubMed2006

In vitro FT-IR study of the effects of hydrogen peroxide on superficial tooth enamel.

OBJECTIVES: The aim of the present study was to determine the alteration in human enamel after hydrogen peroxide treatment using FT-IR spectroscopy. It is hypothesized that infrared spectroscopy is capable of showing alterations in human enamel after peroxide treatment and the alteration in enamel is proportional to peroxide concentration. METHODS: The effects of 10, 20 and 30% hydrogen peroxide solutions on human enamel were tested. Thirty non-carious human teeth, extracted for periodontal reasons, were used in this study. They were divided into 3 groups of 10, according to the peroxide concentration, sectioned, and the specimens were embedded in resin for infrared spectroscopic analysis. The total treatment time was 120 min. Spectra of the specimens were taken before treatment and 30, 60 and 120 min after it. Another spectrum was taken in a week. RESULTS: Infrared spectroscopic analysis showed two distinct bands (biological PO(4)nu1 and nu2) that were capable of describing the alterations in enamel structure. On comparing the infrared spectra of non-treated and treated specimens, structural changes were detected in the superficial enamel. The alteration in enamel was proportional to treatment time and hydrogen peroxide concentration. Higher concentration and longer treatment time resulted in more severe alterations. The numerical analysis of the spectra revealed that on using concentrated hydrogen peroxide solutions the alterations of the IR spectra were more pronounced. The spectra taken in 1 week after treatment did not show spontaneous reversibility in enamel structure. CONCLUSION: At-home and in-office peroxide-containing bleaching agents are capable of causing alteration in enamel at low and high concentrations as well. According to the results of this study it is recommended to perform tooth whitening using low concentration of hydrogen and/or carbamide peroxide, and shorten treatment time to reduce the possible destruction but reach the required change in color.

Dental Enamel↗