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Biomedical subjects

B Ogaard

Publications and source records attributed to B Ogaard.

At least 91 records · Page 5Linked to original sources
PubMed1989

[Cariologic aspects of orthodontic treatment].

An almost linear correlation between plaque accumulation and caries lesion development has been demonstrated in orthodontic patients. Nevertheless, the present fluoride agents and regimens are sufficient to prevent lesion development to such an extent that filling therapy is not required. An increased prevalence of white spot demineralization on the buccal surfaces in orthodontically treated individuals may on the other hand represent an aesthetic problem. Fig 5 summarizes a series of experiments on the effect of fluoride on lesion development during treatment with fixed orthodontic appliances. Whereas daily rinsing with a neutral fluoride solution (0.2% NaF) inhibits lesion development by about 60%, a fluoride solution (0.6% F) at pH 1.9 inhibits lesion development completely under the same experimental conditions. The hypothesis is that the acidic fluoride solution induces an acid resistant layer of calcium fluoride-like material on the enamel surface and/or a large depot of fluoride for release during cariogenic challenges. A fluoride solution at low pH may be recommended for prevention of lesion development during treatment with fixed orthodontic appliances.

Dental Caries↗
PubMed1988

Orthodontic appliances and enamel demineralization. Part 2. Prevention and treatment of lesions.

Clinical experiments were performed to investigate the effect of fluoride on carious lesion development and on lesions established during fixed orthodontic therapy. All presently available fluoride agents are developed from the concept of fluoridating the enamel in the form of fluorhydroxyapatite. Recent research has indicated, however, that calcium fluoride formation may be a major aspect of the mechanism of the cariostatic effect of topical fluoride. Therefore a fluoride solution with very low pH (1.9) that induced large amounts of calcium fluoride also was tested on lesion development underneath orthodontic bands. Daily fluoride mouth rinsing with a 0.2% solution sodium fluoride (NaF) retarded lesion development significantly, whereas the fluoride solution with low pH inhibited lesion formation completely. Fluoride applied as a mouth rinse to plaque-covered lesions underneath orthodontic bands retarded lesion progression. The remineralizing capacity of saliva was found to be rapid in the absence of any fluoride. Although white spot lesions may remineralize and even disappear, most of the emphasis should be directed against prevention of carious lesion development during treatment with fixed orthodontic appliances.

Adolescent↗
PubMed1988

Orthodontic appliances and enamel demineralization. Part 1. Lesion development.

A clinical trial was conducted to investigate carious lesion development associated with fixed orthodontic therapy. Specially designed orthodontic bands for plaque accumulation were attached to premolars scheduled to be extracted as part of an orthodontic treatment. Visible white spot lesions were seen within 4 weeks in the absence of any fluoride supplementation. Both microradiographic and SEM examinations showed surface softening of the enamel surface--that is, a surface layer was not seen in the lesions. The clinical significance of the present study is that enamel demineralization associated with fixed orthodontic therapy is an extremely rapid process caused by a high and continuous cariogenic challenge in the plaque developed around brackets and underneath ill-fitting bands. Careful inspection of the appliance at every visit and preventive fluoride programs are therefore required.

Adolescent↗
PubMed1988

Microradiographic study of demineralization of shark enamel in a human caries model.

The aim of the present study was to compare the resistance of fluoroapatite (shark enamel) and hydroxyapatite (human enamel) against a high caries challenge in a human in vivo model. Two samples of shark enamel and human enamel were each placed in removable appliances in six children and carried for 1 month and a plaque retentive device was placed over each enamel sample. The results showed that the mean total mineral loss (delta Z) was 1680 vol% micron in human enamel and 965 vol% micron in shark enamel. The corresponding mean values for lesion depth were 90 micron and 36 micron, respectively. It is concluded that even shark enamel containing 30,000 ppm F has a limited resistance against caries attacks.

Adolescent↗
PubMed1988

In vivo progress of enamel and root surface lesions under plaque as a function of time.

This paper deals with enamel and root surface demineralization under plaque in vivo as a function of time. The enamel was demineralized using the Ogaard method in which preformed orthodontic bands are attached to the premolars in situ for 4, 6, and 8 weeks; a niche in the bands is responsible for plaque accumulation. In a second experiment cement-covered root surfaces (and enamel) were mounted on a removable appliance (Hawley retainer). Also in this case an orthodontic band was placed over the samples to create a space for plaque accumulation of about 0.8 mm between sample and band. All samples were analyzed by means of microradiography. The results show that (1) demineralization of enamel with the Ogaard method and using the Hawley retainer gives values for lesion depth and mineral loss that are statistically not significantly different; (2) lesion progress and mineral loss in vivo is about 2.5 times faster in roots than in enamel; (3) the demineralization in enamel is roughly linear with time, and (4) roots demineralize in vivo very fast during the 1st week and much more slowly there after.

Dental Caries↗
PubMed1988

Signs and symptoms of craniomandibular disorders in two groups of 19-year-old individuals, one treated orthodontically and the other not.

Fifty-one individuals (28 girls and 23 boys) who had received orthodontic treatment were compared as to signs and symptoms of craniomandibular disorders with 47 individuals (19 girls and 28 boys) without such treatment. All were 19 years old. An average of 5 years had elapsed since the termination of the treatment. The examinations enabled calculations of the anamnestic, the clinical dysfunction, and the occlusal indices of Helkimo. There were no statistically significant differences between the groups except with regard to the anamnestic index. Subjects who had not received orthodontic treatment reported most symptoms, but none were severe. In conclusion, there were no substantial differences as to signs and symptoms of craniomandibular disorders in these two groups of individuals.

Adult↗
PubMed1988

Applicability of acid-etching techniques for fluoride determination on enamel after topical fluoride treatment.

A common technique for fluoride gradient determination of enamel is based on acid-etching of thin enamel layers. The dissolution of CaF2-like material in two different acid-etching solutions was compared with the dissolution of pure CaF2. The results showed that the CaF2-like material deposited on enamel after a topical treatment with 2% NaF dissolved almost completely in the 1 M HClO4 and 1.6 N HCl/70% glycerol solutions. The dissolution of pure CaF2 in the same solutions was low. Even after 30 min, less than 9% of the CaF2 had dissolved. It was concluded that acid-etching techniques for fluoride determination could be used on enamel treated topically with fluoride. The study also indicated that CaF2-like material may have chemical properties different from pure CaF2.

Acid Etching, Dental↗
PubMed1987

SEM and microradiographic investigation of initial enamel caries.

In this paper a combined microradiography and SEM study is presented on human enamel after a caries attack in vivo for a 4-wk period. The initial enamel caries is induced under a specially designed orthodontic band; plaque accumulation takes place under a niche in the band. The microradiography and SEM were done on the same sections. A special manipulation and breaking technique of the thin sections makes it possible to observe with the SEM, demineralized enamel areas with a mineral content known from microradiography. The results show that with a mineral content of about 50 vol. %, the observable porosity is noticeable at the prism level (interprismatically) but barely noticeable at the cyrstallite level. The surface morphology of the demineralized enamel is at low magnifications not very different from sound enamel. At high magnifications, however, the surface porosity becomes visible. The results indicate that the mineral in vivo losses in enamel after an initial caries attack can be explained mainly by mineral losses from interprismatic areas and from the prism peripheries.

Adolescent↗
PubMed1986

A polarized light and scanning electron microscope study of the effect of Duraphat treatment on in vivo caries.

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

Adolescent↗
PubMed1985

Fluoride retention in clean and plaque-covered demineralized enamel in vivo after application of monofluorophosphate.

The retention of fluoride in clean and plaque-covered demineralized enamel in vivo was measured 1 wk after a single application of a MFP solution with low or high content of free fluoride. Demineralization of the enamel was induced in vivo during a 4-wk period prior to application of fluoride by applying orthodontic bands on a pair of premolars scheduled for extraction of orthodontic reasons. The band from one tooth of each pair was then removed and the tooth cleaned (clean enamel lesion). The band on the contralateral tooth (plaque-covered enamel lesion) was left in place. The MFP solutions were applied and the teeth extracted after one more week. The chemical form of fluorine in the lesions was analyzed by conventional acid etching of the enamel combined with KOH dissolution and by a nondestructive surface analysis using ESCA to detect intact monofluorophosphate ions. The ESCA measurements showed that MFP was only present in the clean enamel lesions, indicating complete hydrolysis by dental plaque. Alkali soluble fluoride could be extracted from both plaque-covered and clean enamel lesions. Conflicting results regarding the amount of fluoride uptake in the lesions were obtained with the acid etching and the ESCA technique. It was thus not clearly established whether plaque enhanced fluoride uptake in carious lesions after MFP application.

Acid Etching, Dental↗