Effect of a Fluoridated Toothpaste on Lesion Development in Plaque-Filled Dentine Grooves: An Intra-Oral Study

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The aim was to study remineralization in dentin underneath a biofilm. This was done in a constant depth film fermentor (CDFF) which was modified so that two treatments can be applied simultaneously in one experiment. Forty-five Streptococcus mutans biofilms were grown in grooves in dentin. Growth medium (3.7 g/l BHI, 1.5 mM calcium and 25 mM PIPES) was administered alternately with 2% sucrose pulsing 4 × 30 min/day. Fluoride at 135 ppm as NaF only or in a mixture with 0.2% chlorhexidine was applied for 2 × 5 min/day. The treatments started 5 days after inoculation and lasted 15 days. Five specimens per group were removed at various time points. The biofilms were checked for viability (by plating) and acid content (by capillary electrophoresis). The dentin specimens were analysed for mineral loss and lesion depth (by transversal microradiography). Fluoride treatment had no effect on the viability but reduced lactic acid production by 75%. The mixture treatment reduced the viability by 80% and the lactic acid content by 93% on the first day and later reduced the two parameters to below the detection limits. Significant differences in changes in mineral loss and lesion depth were observed between the treatment groups. Partial remineralization but deeper lesions were observed in the fluoride group, while nearly complete remineralization was seen in the mixture group. In conclusion, the CDFF S. mutans biofilm model can be used as a de- and remineralization biofilm model, and the split mode is particularly suitable for testing caries-preventive agents.

Section: Preparation Of Specimensmentioning

confidence: 99%

Caries-Preventive Agents Induce Remineralization of Dentin in a Biofilm Model

Deng¹,

Loveren²,

Cate³

2005

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“…The in situ dentin groove model [Lagerweij et al, 1997] was used to obtain 7-day-old dental biofilm. In brief, in bovine dentin discs (6 mm diameter) three grooves (0.2 mm wide, 0.7-0.8 mm deep) were cut perpendicularly to the surface of the disc.…”

Section: Specimens and Plaque Growth Conditionsmentioning

confidence: 99%

Dental Plaque as a Biofilm: A Pilot Study of the Effects of Nutrients on Plaque pH and Dentin Demineralization

Zaura

Cate²

2003

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Direct or in situ methods (e.g., confocal microscopy, microsensors) are used to study non-oral biofilms for almost two decades, and they have recently been introduced in the research of dental plaque. We combined a pH microsensor technique and transversal microradiography (TMR) in a pilot study where the effects of nutrient availability on plaque acidogenicity and on the development of caries-like lesions were assessed. One volunteer accumulated dental plaque for 7 days in 0.2-mm-wide and 0.8-mm-deep dentin grooves at four conditions: (1) saliva only, (2) 8 × 5 min/day dipping in 10% sucrose solution, (3) 7 × 5 min/day consumption of sweet cookies plus one meal/day, and (4) subject’s regular diet. Plaque pH versus time and depth profiles in the grooves were recorded ex vivo before and after sugar challenge. ‘Saliva’ plaque responded to sugar with slow pH decrease – minimum pH 5.6–5.8 was reached after 30 min, while sugar dipping resulted in metabolically active plaque (minimum pH 5.3–5.5 within 4–8 min). TMR analysis revealed no demineralization after these two periods. Metabolically active plaque leading to distinct lesions resulted from frequent plaque exposure to diets rich in starch and carbohydrates (groups 3 and 4). These findings strengthen the view that the plaque acidogenicity does not necessarily reflect cariogenicity, and that retention of food components may account for increased cariogenicity at plaque retention sites in the mouth.

“…Jorgensen and Wakumoto [1968] reported no caries in gaps smaller than 35-50 m suggesting that secondary caries lesions do not tend to develop around smaller gaps. Lagerweij et al [1997] reported smaller dentinal lesions in association with narrower grooves.…”

Section: Discussionmentioning

confidence: 95%

Effect of Gap Geometry on Secondary Caries Wall Lesion Development

Nassar

González-Cabezas

2011

Objective: To investigate how the size of the space between restoration and dentinal wall of the tooth affects the development of secondary caries lesions, especially wall lesions. Methods: Tooth-resin composite specimens were mounted on custom-made gap model stages and divided into 4 groups (n = 10): group 1 with a 30-µm gap throughout both enamel and dentin, group 2 with a 30-µm enamel gap and 530-µm dentinal gap, group 3 with 525-µm gaps in both enamel and dentin, and group 4 with 525-µm and 1,025-µm gaps in enamel and dentin, respectively. Specimens were gas sterilized and incubated in a cycling microbial caries model for 8 days and analyzed with confocal microscopy for lesion size at the enamel outer lesion (EOL), enamel wall lesion (EWL), dentin wall lesion A (DWL-A) next to the dentin-enamel junction (DEJ) and dentin wall lesion B (DWL-B) at 750 µm from the DEJ. Results: No difference in EOL or EWL size was found between the groups. DWL-A and DWL-B were larger in group 3 than groups 1 and 2. A larger DWL-B was found in group 3 than group 4. Conclusions: The presence of additional space at the dentinal wall area did not affect secondary caries development as long as the enamel gap was small. However, with enamel gaps of approximately 500 µm, the presence of the additional gap space at the dentinal wall led to the development of smaller dentinal wall lesions at the deeper parts of the simulated cavity. In uniform gaps, the size of the interface was positively correlated with the size of the dentinal wall lesions.