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Biomedical subjects

A Itthagarun

Publications and source records attributed to A Itthagarun.

15 recordsLinked to original sources
PubMed2005

The effects of child formula toothpastes on enamel caries using two in vitro pH-cycling models.

AIMS/OBJECTIVES: To compare, using two pH-cycling models, the de/remineralisation effects of children's toothpastes on primary teeth. DESIGN: In vitro single-section and pH-cycling models. METHODS: Primary teeth were placed in demineralising solution for 96 hours to produce artificial carious lesions 60-100 microm deep. They were cut into 100 microm thick sections and assigned to 6 groups. Sections in Groups A and D were exposed to a non-fluoridated toothpaste, those in Groups B and E to half-pea-sized (0.16g) and those in Groups C and F to pea-sized portions (0.32g) of a 500ppm F toothpaste. pH-cycling Model I (Groups A, B, C), without added fluoride, ran for 7 days, while Model II (Groups D, E, F), with 0.25ppm F, ran for 10 days. OUTCOME MEASUREMENTS: Lesions were evaluated using polarised light microscopy and microradiography. RESULTS: Lesions in Groups B and E progressed by 64% and 61%, respectively, while those in Groups C and F progressed by only 19% and 23% respectively. CONCLUSIONS: Both 10-day and 7-day pH-cycling models were suitable for studying carious lesion progression in primary teeth (the demineralising and remineralising solutions of the 10-day cycling model contained 0.25ppm F). A pea-sized portion (0.32g) of 500ppm F toothpaste slowed down the demineralisation progression better than a half-pea-sized portion.

Cariostatic Agents↗
PubMed2002

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.

Acid Etching, Dental↗
PubMed2001

Adverse surface interactions between one-bottle light-cured adhesives and chemical-cured composites.

OBJECTIVES: This study examined the effect of one-bottle adhesives with different acidities on bonding to chemical-cured and light-cured resin composites. METHODS: Twenty-four non-carious human third molars were divided into eight groups. A flat dentin surface was created for each tooth. Acid-conditioned dentin surfaces were bonded with Prime&Bond NT (Dentsply), OptiBond SOLO (Kerr), Single Bond (3M) or One-Step (Bisco). Each adhesive group was covered with composite buildups, using either a light-cured (Z100, 3M) or a chemical-cured composite (BisFil 2, Bisco). Specimens were vertically sectioned into 0.9x0.9 mm beams. Microtensile bond strengths were recorded and failure modes were classified using a stereoscopical microscope. Four representative beams from each group were further prepared for SEM examination. RESULTS: Two-way ANOVA showed that the effect of adhesive types, composite curing modes and their interaction were statistically significant (P<0.001). Multiple comparison tests revealed no statistically significant difference in the bond strength of the four adhesives with the light-cured composite (P>0.05). However, they were significantly lower when used with the chemical-cured composite (P<0.01). A positive correlation was observed between the acidity of adhesives and the bond strengths of the chemical-cured composite. Failure occurred predominantly along the composite-adhesive interface, with microporosities on the adhesive surface and voids within the chemical-cured composite. SIGNIFICANCE: Air incorporated during mixing of chemical-cured composites only contributed partially to the decreased bond strength observed in simplified-step adhesives. Ultrastructural observations suggested the presence of a surface interaction between the uncured, acidic resin monomers from the oxygen inhibition layer of the adhesive and the initiator components in the chemical-cured composite.

Acrylic Resins↗
PubMed2001

The effect of fluoridated and non-fluoridated rewetting agents on in vitro recurrent caries.

OBJECTIVE: This study examined the in vitro caries inhibiting potential of fluoridated and non-fluoridated rewetting agents that are applied to acid-etched enamel and dentine before the use of a water-free, dentine adhesive. MATERIALS AND METHODS: Twelve caries-free premolars were divided into three groups of four teeth each. 2 x 3 x 1.5 mm cavities were prepared on the mesial and distal surfaces of each tooth, with half of the cavosurface margin in enamel and half in root dentine. In Group I (control), One-Step (Bisco, Schaumburg, USA) was applied without etching or rewetting agents. In Group II, cavities were acid-etched, rinsed, dried, and rewetted with Aqua-Prep (Bisco), a non-fluoridated rewetting agent, and then bonded with One-Step. Treatment for Group III was similar to Group II, except that Aqua-Prep F (Bisco), a fluoridated rewetting agent was used. Bonded cavities were restored with a non-fluoride-containing flowable composite (AEliteFlo, Bisco). Artificial carious lesions were induced in these specimens, from which multiple 100+/-20 microm thick longitudinal sections were prepared, yielding 16 specimens per group for evaluation with polarised light microscopy (PLM) and microradiography (MRG). Representative sections were processed for transmission electron microscopy (TEM) examination and scanning transmission electron microscopy/energy dispersive X-ray (STEM/EDX) analyses. RESULTS: The differences in demineralisation of dentine among the groups were not statistically significant for 'relative' lesion depth (p > 0.05, ANOVA, Student-Neuman-Keuls test), but highly significant for 'relative' lesion area (p < 0.001). Wall lesions were consistently present in Group I, while inhibition zones were invariably observed in Group III. 87.5% of Group II specimens exhibited neither wall lesion nor inhibition zone. TEM showed that remnant dentine apatite crystallites within the inhibition zones in Group III were larger and denser than those present within the corresponding wall lesions. STEM/EDX analyses confirmed the presence of calcium, phosphorus and fluorine in these plate-like crystallites. CONCLUSION: When used with a water-free, single-bottle dentine adhesive, a non-fluoridated rewetting agent is able to reduce, but cannot completely prevent recurrent caries. The use of a fluoridated rewetting agent is useful under the situation when microleakage occurs, by providing the additional benefit of fluoride-induced demineralisation inhibition.

Analysis of Variance↗
PubMed2000

The effect of different commercial dentifrices on enamel lesion progression: an in vitro pH-cycling study.

AIMS/OBJECTIVES: To evaluate and compare the de/remineralization effects of dentifrices manufactured locally in some developing countries. DESIGN: Utilisation of the in vitro single-section and the pH-cycling model. SETTING: Laboratory. TEST MATERIALS: Dentifrices: Maxam DFP, Maxam Tartar Control, First, Tianqi Medicated from China; Vicco Vajradenti from India; Colgate MFP2, Crest Tartar Control from USA; and one non-fluoride dentifrice as control. METHODS: Sound molars were painted, leaving a 1 mm wide 'window' on the buccal and/or lingual surface and placed in a demineralisation solution for 96 h to produce artificial caries lesion approximately 80-100 mm deep. The teeth were then longitudinally sectioned (approximately 100 mm thick), and randomly divided into 8 groups (22 sections/group). The pH cycling model was utilised for 10 days. OUTCOME MEASURES: Polarised light microscopy and microradiography were used to evaluate the lesion progression before and after treatment. RESULTS: The control group showed an increase in lesion depth of 70 per cent and was statistically different from some test groups which ranged from -2 per cent to 68 per cent (P < 0.01, t-test). Statistically significant differences were also observed among some of the fluoride containing groups. CONCLUSIONS: This study suggests that, when compared to 'multinational dentifrices', Chinese and Indian dentifrices manufactured locally failed to show 'healing' efficacy even though they claimed to contain varying levels of fluoride.

China↗
PubMed2000

Ultrastructural identification of cells involved in the healing of intramembranous bone grafts in both the presence and absence of demineralised intramembranous bone matrix.

Alveolar bone defects are conditions that impede the progress of orthodontic treatment. This study compared the mechanics of the healing of autogenous intramembranous (IM) bone grafts and grafts comprising a mixture of IM and demineralised bone matrix of autogenous intramembranous origin (DBMIM), in an attempt to determine the reliability of each material. Thirty-two New Zealand white rabbits had a single defect created in their skull. Sixteen were grafted with IM bone alone (Group I: autogenous IM), and the other 16 had a combined graft of composite IM sandwiched between two layers of DBMIM (Group II: composite IM-DBMIM). A third group (Group III) of eight rabbits each had two defects created in their skull; one defect was left empty (A: passive control) and the other filled with rabbit-skin collagen (B: active control). In Groups I and II, inflammatory cells were found to be present on Days 1 and 2 of tissue retrieval. The appearance of the mesenchymal cells and preosteoblasts, osteoblasts and osteocytes was earlier (Day 3) in Group II than in Group I (Day 5). In both groups, preosteoblasts, osteoblasts and osteocytes were observed with no cartilage at the intermediate stage. In conclusion, autogenous IM bone grafts and IM bone grafts in the presence of DBMIM healed through an osteogenic ossification route.

Animals↗
PubMed2000

Oral rehabilitation of a hypohidrotic ectodermal dysplasia patient: a 6-year follow-up.

This case report describes the oral rehabilitation of a female child with hypohidrotic ectodermal dysplasia over a 6-year time period. It demonstrates the need for periodic modification and replacement of a prosthesis, an orthodontic appliance, and a gingivoplasty. Although the initial treatment plan was considered to be a compromise due to limited cooperation, an improvement was observed in the patient's social behavior as a consequence of her dental treatment. The effects of unavoidable changes in the dental team over 6 years are also discussed.

Anodontia↗
PubMed2000

Bonding of a self-etching primer to non-carious cervical sclerotic dentin: interfacial ultrastructure and microtensile bond strength evaluation.

PURPOSE: The objectives of this study were 1) to examine the ultrastructural features of the resin-sclerotic dentin interface following the application of Clearfil Liner Bond II sigma to natural cervical wedge-shaped lesions, and 2) to evaluate the regional tensile bond strength of this self-etching primer at different locations on natural and artificially-created cervical lesions. MATERIALS AND METHODS: Deep cervical natural lesions were bonded using the self-etching primer. Micromorphology of the bonded interface at different locations within the lesions were examined using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and scanning transmission electron microscopy/energy dispersive x-ray analysis (STEM/EDX). Ultrastructural features were further compared with the use of the same self-etching primer on artificial lesions created in sound cervical dentin. A nontrimming technique was used to evaluate the regional tensile bond strength from the occlusal, gingival, and the deepest central part of both natural and artificial cervical lesions. Beams with a mean area of 0.46 +/- 0.03 mm2 were prepared and were pulled to failure using a Bencor Multi-T testing device attached to an Instron universal tester. Bond strength results were evaluated using a two-way ANOVA design. RESULTS: A hypermineralized layer devoid of intact, banded collagen was invariably present on the surface of the natural lesions. Depending upon its thickness at different locations of the lesion, the action of a self-etching primer may be limited to this surface layer alone, producing a hybridized hypermineralized surface layer. Penetration of the self-etching primer into the underlying sclerotic dentin produced a hybridized complex containing a hybridized hypermineralized surface layer as well as a subsurface layer of hybridized intertubular dentin. Bacterial colonization of the lesion surface resulted in the formation of an additional zone of hybridized intermicrobial matrix over the surface of the lesions. Dentinal tubules remained blocked with sclerotic casts, and resin tags were rarely observed. Regional tensile bond strength results showed that the overall bond strength to natural sclerotic dentin was about 20% lower than sound cervical dentin, but was independent of the different locations within the lesions from which bond strength was evaluated. CONCLUSION: There were four factors that may have influenced the overall decrease in bond strength in natural cervical sclerotic lesions: a) the presence of a hybridized intermicrobial matrix together with entrapped bacteria may have weakened the bonds, b) inability of a self-etching primer to etch through a thick, hypermineralized surface layer, c) presence of a layer of possibly remineralized, denatured collagen at the base of the hypermineralized surface layer, and d) retention of acid-resistant sclerotic casts that obliterate the tubular lumina and prevent effective resin tag formation.

Acid Etching, Dental↗
PubMed2000

Self-contamination of deep dentin by dentin fluid.

PURPOSE: To compare, with the use of a resin replica technique, surface features of deep, acid-conditioned dentin from vital human molars that were anesthetized with an anesthetic: Group 1: without a vasoconstrictor (Mepivacaine 3%), and Group 2: containing a vasoconstrictor (Lidocaine 2% with 1:80,000 epinephrine). MATERIALS AND METHODS: 10 Class I cavities with dentin caries were included in each group. Following complete caries removal, a total-etch technique was performed with 32% phosphoric acid (Uni-Etch) for 15 s. After rinsing, each cavity was air-dried for 1 s, then a slow setting vinyl polysiloxane (President) impression was taken. As a control, impressions were taken from three additional cavities in teeth that were anesthetized with Mepivacaine 3% but not acid etched. A TEM-grade epoxy resin was used to prepare replicas from the impressions. Polymerized replicas were coated with gold and examined with a scanning electron microscope. RESULTS: In Group 1, fluid was visible leaving tubular orifices in all replicas. In addition, three were covered with a smooth, amorphous film that was different from the granular appearance of the smear layer in the control cavities. In Group 2, patent tubular orifices without fluid were observed in all specimens. Odontoblast process-like structures were seen from some dentin tubules.

Acid Etching, Dental↗
PubMed1999

Morphology of initial lesions of enamel treated with different commercial dentifrices using a pH cycling model: scanning electron microscopy observations.

The aim of this study was to evaluate and compare the 'calcium fluoride-like reaction products' formed, both on the surface and in the subsurface caries-like lesions of enamel, from different commercial dentifrices manufactured locally from developed and developing countries. The experiment was conducted by using the in vitro single-section technique under the pH-cycling system used for 10 days. The tested dentifrices include; Maxam DFP Maxam Tartar Controls, First, Tianqui Medicated (China); Vicco Vajradenti (India); Colgate MFP2. Crest Tartar Control (USA); and a non-fluoride dentifrice, Jie Yin (China) used as control. The surface and subsurface of the lesions, before and after treatment, were examined using scanning electron microscopy. Varying degrees of fine globular patterns of calcium fluoride-like material were observed on the enamel surfaces of five out of eight groups and in the subsurface of four groups. Two treatment groups showed a 'similar appearance' compared with the control and untreated groups. This study suggests and supports that, when compared with 'multinational dentifrices', some Chinese and Indian dentifrices manufactured locally failed to induce the typical morphological appearance of globules as seen with fluoride dentifrices.

Calcium Fluoride↗
PubMed1997

Ectodermal dysplasia: a review and case report.

Ectodermal dysplasia is a hereditary disease characterized by a congenital dysplasia of one or more ectodermal structures and their accessory appendages. Common manifestations include defective hair follicles and eyebrows, frontal bossing with prominent supraorbital ridges, nasal bridge depression, and protuberant lips. Intraorally, common findings are anodontia or hypodontia, conical teeth, and, consequently, generalized spacing. The patient may suffer from dry skin, hyperthermia, and unexplained high fever as a result of the deficiency of sweat glands. The present review focuses on the clinical manifestations, classifications, and diagnosis of ectodermal dysplasia. A 6-year-old girl, described in the case report, exhibited many of the manifestations of ectodermal dysplasia as well as behavioral problems and a severe gag reflex. The treatment to improve her appearance and oral function included a removable prosthesis, acid-etch-retained indirect resin composite veneers, and a fixed partial denture.

Anodontia↗
PubMed1997

Chewing gum and saliva in oral health.

The crucial role played by many properties of saliva in preventing dental caries, maintaining the plaque pH and controlling the equilibrium between enamel de- and remineralization has been demonstrated. This has been documented by the effects of salivary dysfunction on caries incidence and by the distribution of sites of caries predilection in areas where saliva presence is restricted. The use of sugar-free chewing gum has been increasingly accepted as one adjunct to oral hygiene procedures. It has become part of an anti-caries prevention program, especially in patients suffering from xerostomia. Chewing gum not only acts as a salivary stimulant but may also be a useful vehicle for some agents such as fluoride, chlorhexidine and calcium phosphate. Moreover, in some countries gum containing nicotine has been used to substitute the nicotine from cigarettes to reduce the effects of nicotine withdrawal reaction from people attempting to stop smoking.

Carbohydrates↗
PubMed1996

Prevalence of oral lesions in a selected Vietnamese population.

Clinical examination of the oral and peri-oral regions of a cohort of 550 Vietnamese living in a refugee camp in Hong Kong was conducted. They comprised 216 (39 per cent) males and 334 (61 per cent) females and their age ranged from 2 to 60 years. A positive clinical finding was observed in 14 per cent, 35 males and 43 females. The most common condition observed was periapical infection (36 per cent), either with an abscess or a sinus. Other lesions noted include mucocele (10 per cent), traumatic ulcers (9 per cent), tori, either palatal (6 per cent) or mandibular (3 per cent), lymph node enlargement (7 per cent), pulp polyp (6 per cent), angular cheilitis (4 per cent), papillomas (3 per cent), cellulitis (3 per cent) and herpes lesions (2 per cent), 7 out of 9 (78 per cent) mucoceles were found in females. No malignant lesions were noted.

Adolescent↗
PubMed1996

Analysis of fluoride ion concentrations and in vitro fluoride uptake from different commercial dentifrices.

The effectiveness of fluoride (F) dentifrices in reducing dental caries is well documented. However, not all F dentifrices are equally effective. The objective of this study was to compare fluoride uptake from Thai, Chinese and Indian dentifrices which are widely used in these respective countries. A non-fluoride dentifrice was included as a control. Dentifrices were analysed for fluoride concentrations using the 'acid-etch biopsy technique'. This study suggests that, when compared to 'multinational dentifrices', the Thai, Chinese and Indian dentifrices manufactured locally failed to show the F availability and/or F uptake efficacy even though they claimed to contain varying levels of F.

Acid Etching, Dental↗