Biomedical subjects

E S Grossman

Publications and source records attributed to E S Grossman.

At least 19 recordsLinked to original sources

PubMed2005

Does mechanical pressure force bacteria into the dentinal tubules of carious and non-carious teeth--an exploratory study.

BACKGROUND: Although many researchers have confirmed bacterial migration within dentine, no evidence was found to show whether bacteria can be easily forced into dentine during caries treatment. OBJECTIVES: This exploratory study was to see if bacteria could be easily forced into dentinal tubules of carious and non-carious teeth using hand excavation and air pressure. METHODS: Two (2) carious and ten (10) non-carious teeth were used. Class I (Black's Classification) cavities were created using rotary instruments in the non-carious teeth, while the carious teeth were excavated using hand instruments to remove the caries. The cavity of one carious tooth was etched and in the other tooth was not. Five (5) of the non-carious tooth cavities were etched, of which, one tooth was also disinfected. The remaining five non-carious teeth were not etched and included one tooth that was disinfected. Bacterial cultures of S. mutans, E. coli and Veilonella were placed in the prepared cavities and hand excavators and air pressure were used in an attempt to force bacteria down into the dentinal tubules. Thereafter, the teeth were fixed, decalcified and prepared for electron or light microscopy. RESULTS: One etched, and one etched and disinfected non-carious tooth showed bacteria in the dentinal tubules. One carious tooth (etched) showed bacterial presence in the dentinal tubules. CONCLUSION: This study shows that it is difficult to force bacteria into dentinal tubules using hand excavation (as in the Atraumatic Restorative Treatment technique) so a definitive study is not indicated.

Acid Etching, Dental↗

PubMed2005

Measurement of dental restorative material topography.

INTRODUCTION: The tracing of peaks and valleys produced during surface profiling of dental materials are read against a mean line which can be modified in the form of a line or arc. Roughness (R) is commonly used to measure the topography of restorative materials, but the profile (P) value is also generated during the tracing and includes both roughness and waviness of the surface. AIMS AND OBJECTIVES: The purpose of this study was to determine if line and arc modified tracings and R and P surface topography measurements give similar results. METHODS: Thirty six cavities (5 x 1.5mm) were prepared in Perspex discs, restored with Fuji IX, a high strength glass ionomer cement, following the Atraumatic Restorative Treatment (ART) technique and the surface of six cavities were each treated as follows: press finger with vaseline (Va); press finger with polyacrylic acid (Aa); carving (Ca); burnishing (Bu); Mylar strip (My); polishing (Po). Topography was assessed using a profilometer which ran three equidistant tracings (3.6mm) on each surface giving a total of 18 readings for each treatment (n=6). The results of Ra, Rv, Rp, R, and Pa, Pv, Pp, P, for all 6 surface treatments were compared and analysed using ANOVA and Tukey's studentised range test with significance set at P<0.05. RESULTS: Within R + line, R + arc, P + line and P + arc, significant differences were apparent between treatments. Pairwise comparisons showed fewer instances of significant differences between surface treatments when R + line (1 instance of significant difference) was compared to R + arc (2). P + line showed 12 instances of significant differences between surface treatments while P + arc showed no difference. CONCLUSION: Both line and arc tracings gave similar results for R and either may be used in assessing surface roughness. The total deviation of the profile P showed more significant differences between treatments with line than with arc and may be a more sensitive tool when dealing with small sample numbers or subtle differences between surface treatments.

Analysis of Variance↗

PubMed2004

Marginal adaptation of mineral trioxide aggregate (MTA) compared with amalgam as a root-end filling material: a low-vacuum (LV) versus high-vacuum (HV) SEM study.

AIM: To compare the marginal adaptation of mineral trioxide aggregate (MTA) or amalgam root-end fillings in extracted teeth under low-vacuum (LV) versus high-vacuum (HV) scanning electron microscope (SEM) viewing conditions. METHODOLOGY: Root-end fillings were placed in 20 extracted single-rooted maxillary teeth. Ten root ends were filled with MTA and the other 10 root ends were filled with amalgam. Two 1 mm thick transverse sections of each root-end filling were cut 0.50 mm (top) and 1.50 mm (bottom) from the apex. Gap size was recorded at eight fixed points along the dentine-filling material interface on each section when uncoated wet (LV wet (LVW)) and dry under LV (0.3 Torr) in a JEOL JSM-5800 SEM and backscatter emission (LV dry uncoated (LVDU)). The sections were then air-dried, gold-coated and gap size was recorded once again at the fixed points under HV (10(-6) Torr; HV dry coated (HVDC)). Specimen cracking, and the size and extent of the crack were noted. RESULTS: Gap sizes at fixed points were smallest under LVW and largest under HVDC SEM conditions. Gaps were smallest in MTA root-end fillings. A General Linear Models Analysis, with gap size as the dependent variable, showed significant effects for extent of crack in dentine, material and viewing condition (P = 0.0001). CONCLUSIONS: This study showed that MTA produced a superior marginal adaptation to amalgam, and that LVW conditions showed the lowest gap size. Gap size was influenced by the method of SEM viewing. If only HV SEM viewing conditions are used for MTA and amalgam root-end fillings, a correction factor of 3.5 and 2.2, respectively, may be used to enable relative comparisons of gap size to LVW conditions.

Aluminum Compounds↗

PubMed2004

Spreadability of two glass ionomer cements used in atraumatic restorative treatment (ART).

'Press finger' in atraumatic restorative treatment (ART) is used to spread a glass ionomer cement (GIC) to seal the restoration margin and adjacent pits and fissures. This study compared the spreadability of Fuji IX and Ketac-Molar to establish which was best suited for this purpose. Twenty equally spaced cavities (35 mm apart) were machine-cut in each of two Perspex slabs 200 x 100 x 20 mm. Each cavity was 3 mm deep with a 4 mm diameter. Two V-shaped grooves 1 mm deep were cut to traverse the cavities: one 0.5 mm wide, the other 0.25 mm wide. Equal amounts (0.25 ml) of GIC were dispensed, 20 cavities for Fuji IX and 20 for Ketac-Molar and condensed under light finger pressure using a 20 mm diameter cork thinly coated with petroleum jelly. This allowed the GIC to be condensed into the cavity and spread into the differently sized grooves. The samples were stored in deionised water for 24 hours whereafter the length to which the GIC had spread along each groove from the cavity edge was measured to the closest 0.01 mm. The data were analysed using ANOVA and the unpaired Student's t-test (P < 0.05). There was a statistically significant difference between the length of spread of the two GICs (t = 2.534; P = 0.013) which was confined to the 0.25 mm width groove (t = 2.83; P = 0.007) with Fuji IX spreading much further along the groove (10.25 +/- 1.17 mm) than Ketac-Molar (7.66 +/- 4.21 mm). Fuji IX appears to be the better sealant material when selecting for spreadability in ART.

Analysis of Variance↗

PubMed2004

Scientific surface roughness values for resin based materials.

INTRODUCTION: Surface roughness of dental restorative materials is most often established with the Ra value obtained using profilometry or by assessing surface topography with the scanning electron microscope (SEM). Both methods should validate each other in confirming surface roughness. AIMS AND OBJECTIVES: The purpose of this study was to compare surface roughness values obtained with a profilometer to the SEM appearance of 6 resin-based restorative materials and assess whether Ra was appropriate as a sole surface roughness measure. Methods Six 5mm diameter specimen discs of Prodigy (Pr); Z100 (Z); Compoglass F (C); Hytac Aplitip (H); Photac-Fil (Pf) and Vitremer (V) were prepared against Mylar strips and stored in distilled water for 14 days. One side of each disc was sequentially polished with Soflex discs to super fine state, the other side remained unpolished. Three surface roughness measurements were made on each surface (n=18) recording Ra, Rv, Rp and Rt values, this data was subjected to a four way ANOVA and Tukey's Studentised Range Test (p=0.05). Two unpolished and two polished discs per material were prepared for SEM, evaluated and visually grouped for surface roughness. RESULTS: Approximate ascending order of roughness was Z, Pr, H, C, V, Pf for Ra, Rv, Rp and Rt and un/polished treatment. Polishing increases surimens into a "bland" (Pr, H, Z, C) and "textured" group (Pf and V). The polished specimens gave four groups: (Pr), (Z and C), (H) and (V and Pf) of increasing surface complexity. Polishing caused surface scratching, removed the matrix, reduced or removed filler particles and exposed voids within the material. CONCLUSIONS: This study emphasises the importance of using more than one technique to assess surface roughness. Rv and Rp values should be utilised to better understand polish induced surface feature changes. Rv maximum is a better measure to identify surface defects which could affect restoration longevity.

Analysis of Variance↗

PubMed2003

How well do fourth year Wits dental students place resin composite restorations?

OBJECTIVES: To evaluate, by means of a scanning electron microscope (SEM) the quality of resin composite restorations, placed as a first attempt by fourth-year dental students. METHODS: Ten Class IV direct composite restorations, placed in plaster-mounted extracted incisor teeth as part of pre-clinical course requirements, were selected. Specimens were evaluated and graded on a two-point scale by a staff member according to departmental clinical evaluation criteria. Five restored teeth were prepared for surface evaluation of marginal integrity, surface roughness and contour using SEM. The remaining specimens were embedded in resin and ground down transversely, parallel to the incisal edge until a dentine core was apparent. The ground surfaces were polished, prepared for SEM and assessed for etched layer, placement of bonding agent, composite adaptation and overall consistency. RESULTS: Clinical assessment and SEM surface evaluation correlated favourably for all criteria, except contour, indicating that students were reasonably competent in finishing techniques. Ground samples revealed acceptable etched enamel layers and marginal adaptation. Bonding agent thickness varied between 0 and 200 microns casting doubt on procedural accuracy. Porosities and voids were apparent within the resin composite. Internal features were the main reason for unsatisfactory grades. CONCLUSIONS: Students placed restoration satisfactorily. They would benefit if able to examine sectioned restorations to understand critical placement techniques which would contribute to resin composite restoration success. A research component can be introduced into the dental undergraduate curriculum by way of similar projects linked to didactic course-work.

Clinical Competence↗

PubMed2002

Comparative cost of ART and conventional treatment within a dental school clinic.

BACKGROUND: The changing oral health needs in South Africa require that both the teaching and clinical techniques of atraumatic restorative treatment (ART) form a part of the restorative undergraduate curriculum. OBJECTIVE: This study was undertaken to establish and compare the estimated costing of an amalgam, composite resin and ART restoration within the Board of Health Funders (BHF) recommended scale of benefits at the School of Oral Health Sciences Oral and Dental Hospital, University of the Witwatersrand (SOHS). METHODS: Fixed and variable costs were calculated by pricing items and equipment used in each procedure. The output values were established according to the recommended scale of benefits (BHF, 1999). This enabled the calculation of contribution margins and net income for each of the three restorations. RESULTS: The annual capital cost for the ART approach is approximately 50% of the other two options (e.g. per multiple surface restoration ART = R1.58; amalgam and composite resin restorative procedures: R3.12 and R3.10 respectively), despite the fact that ART restorations are rendered in a modern dental setting. CONCLUSIONS: Our study shows that implementation of the ART approach within the clinic setting of the SOHS can be accomplished without additional cost. Furthermore ART can be performed as an economically viable alternative to conventional treatment procedures within the clinic setting. The study represents a first step towards determining the cost efficiency of implementing ART as a pragmatic and cost-effective restorative option within the SOHS, University of the Witwatersrand.

Capital Expenditures↗

PubMed2002

Accurate diagnosis of occlusal carious lesions--a stereo microscope evaluation of clinical diagnosis.

This study was undertaken to validate the caries status of 214 teeth by serial sectioning and microscopy after caries diagnosis using four methods. Two hundred and fourteen extracted human teeth with varying degrees of caries were mounted in the jaws of nine training manikins. All tooth surfaces were examined and recorded for caries by four dentists using bitewing radiographs, fibre-optic transillumination (FOTI), mirror alone and a mirror and sharp probe on two separate occasions. Thereafter the teeth were serially sectioned and assessed microscopically for depth of caries lesion on a graded score of 0-7. This report assessed the diagnostic outcome of 2,183 observations for occlusal surfaces. Sound diagnoses predominated over unsound until caries was present in the inner half of dentine. Specificity was between 90% and 95% and sensitivity 26% and 50% depending on which diagnostic method was used and where the sound/unsound threshold was set. Negative and positive predictive values were similarly influenced and varied between 53% and 80% and 73% and 90%, respectively. Probit analysis showed no significant differences (P < 0.05) between examiners and diagnostic methods. Diagnosis of occlusal caries undertaken in an in vitro simulated clinical situation is inaccurate until the caries lesion extends deep into the dentine no matter which of the four methods was used.

Chi-Square Distribution↗

PubMed2002

Microscope observations of ART excavated cavities and restorations.

This in vitro light and scanning electron microscope study examined 39 extracted tooth specimens, hand excavated and restored according to atraumatic restorative treatment (ART), using 'press finger', by 'skilled' and 'novice' operators. Surface features of five excavated cavities, 12 restoration surfaces and the tooth restoration relationships of 22 bisected restored tooth crowns were examined to better understand the clinical effect of the technique. Hand-excavated cavity surfaces were rough with a complex surface arrangement of grooves, crevices, ridges, furrows and overhangs. Enamel and dentine were covered with debris except where surface fractures exposed enamel prisms and occluded dentinal tubules. Ten of the 22 bisected restored specimens had large voids (1-3 mm in length) within the glass-ionomer cement (GIC) restoration or at the tooth-restoration interface. Smaller bubbles (< 50 microns) and irregular shaped inclusions were common in all restorations. Adaptation of the GIC to the cavity margin was extremely variable and easily distinguished from the effects of dehydration shrinkage. It is thought that cavity surface irregularities could cause placement problems making it difficult to adapt the GIC to cavity peripheries. While 'press finger' enabled excellent penetration of GIC into fissures, the technique left restoration surfaces rough. At low magnification, surfaces were irregular; at magnifications higher than X500 scratches, pits, porosities, chipping and voids were evident. However, the 'press finger' technique was able to merge the GIC to a fine edge on the occlusal surface so that the restoration margin was not obvious. No apparent difference was found between the restorations placed by the 'skilled' and 'novice' operators. Tooth-restoration relationships in the ART approach are entirely different to those of traditional restorative techniques. The ART approach requires skill, diligence and comprehension to be undertaken correctly.

Clinical Competence↗

PubMed2001

Bonding agents: adhesive layer thickness and retention to cavity surfaces with time.

This study assessed bonding agent thickness, cover and the influence of long-term storage on bonding agent retention to enamel and dentine surfaces in cut occlusal cavities in 46 human molar teeth. Two specimens were etched and set aside. The remaining specimens were divided into two equal groups and treated with either Optibond or Scotchbond Multipurpose Plus (SMPP) up to the adhesive stage. Thereafter two specimens from each group were stored for 0, 1, 3, 7 and 14 days and 1, 2, 3, 6 and 12 months in 1% NaCl. After storage the cavity surfaces were examined in a scanning electron microscope (SEM) and scored as to bonding agent cover. One specimen from each treatment was then embedded in resin, two sections prepared midway through each cavity, polished and re-examined in the SEM to measure bonding agent thickness at 13 sites along the cavity surface. Both bonding agents showed highly variable and significant (P < 0.05) bonding agent cover and layer thickness according to cavity site, SMPP more so than Optibond. Pooling of SMPP adhesive was apparent in cavity angles. Mean film thickness was significantly different between Optibond (221 +/- 130 microns) and SMPP (118 +/- 106 microns). There was no significant difference in bonding agent thickness between long- and short-term storage.

Analysis of Variance↗

PubMed2001

Surface roughness of aesthetic restorative materials: an in vitro comparison.

The purpose of this study was to compare the surface roughness of three types of aesthetic restorative material. Six standard samples of two brands of each type of material were prepared namely: hybrid composites (Prodigy, Z100), compomers (Compoglass F, Hytac Aplitip) and glass ionomer cements (Photac-Fil, Vitremer) in a perspex mould (N = 36). Upper and lower surfaces were covered with Mylar strips which, in turn, were covered with glass slides and compressed to express excess material. After light curing, specimens were stored in distilled water for 14 days. Thereafter, one side of each specimen was polished sequentially with medium, fine and super fine Soflex discs (treatment). Untreated surfaces served as controls. All surfaces were examined with Talysurf and the surface roughness (Ra) of each specimen was recorded. Three measurements were made of each specimen. A 4-way ANOVA and Tukey's Studentised range test were used to analyse the data. Statistically significant effects were found for both type of material (P = 0.0001) and for treatment process (P = 0.0065). Among unpolished specimens: Compoglass F is significantly rougher than Vitremer, Z100, Prodigy and Hytac Aplitip, and compomers are significantly rougher than hybrids. Among polished specimens: Photac-Fil is significantly rougher than Z100 but does not differ from Compoglass F, Vitremer, Prodigy and Hytac Aplitip, and glass ionomers are also significantly rougher than hybrids. The smoothest surface is obtained when curing materials against a Mylar strip.

Analysis of Variance↗

PubMed2000

Performance of early-blind and sighted children on olfactory tasks.

The goal of the study was to test whether children with congenital or early-onset blindness outperform sighted children on olfactory tasks. Measures of olfactory sensitivity, odour recognition, and odour labeling were obtained. The results show that the blind children were more proficient at correctly labeling 25 common odours than were matched sighted children. However, the blind were not more sensitive to a target odour, nor more proficient at choosing a correct odour label from a list of four. Together, the data point to a circumscribed advantage of blind children at self-generating and retrieving odour labels and, as such, to a limited, but still compensatory, cognitive function.

Adolescent↗

PubMed1999

Histological features of artificial secondary caries adjacent to amalgam restorations.

Artificially induced carious lesions on either side of in vitro un/restored amalgam cavities were examined to establish the degree of randomness of caries development. Class I cavities were cut in 132 extracted premolars: twelve teeth were not restored, and 120 teeth were restored with one of 20 different restoration combinations of silver amalgam, base and varnish. After ageing for periods of 3 months and 1 year, the 12 unrestored teeth and 80 of the restored teeth were subjected to an in vitro bacterial challenge for 36 days, while the other 40 specimens were challenged in acidified broth (pH 4.0). Sections were then prepared for polarized light microscopy. Carious lesion configuration on either side of the cavity was noted, and outer, wall and dentine lesions measured. Data underwent Fisher's exact test, a chi-squared goodness of fit test and a Student's paired t-test with P<0.05. Except for dentine lesions, acid broth and unrestored specimens showed carious lesions having similar size and occurrence on either side of the cavity. Two unrestored cavities showed caries resistance. Restored, bacterially challenged specimens were significantly different regarding total and wall lesion distribution and wall lesion width and area on either side of the cut cavity. Acid broth challenge will promote regular caries development at the tooth-restoration interface. The random caries pattern which developed in restored bacterially challenged specimens indicates that the tooth-restoration interface forms a diverse environment providing sites of varying susceptibility to caries.

Bicuspid↗

PubMed1999

Reliability of outer lesion secondary caries as a predictor of wall lesions.

PURPOSE: To assess the reliability of in vitro developed secondary caries outer lesions as an indicator of presence and extent of wall lesions. MATERIALS AND METHODS: Class I occlusal cavities were cut in 132 extracted premolars: 12 teeth were not restored, 120 restored with one of 20 different restoration combinations of silver amalgam, base and varnish. Specimens were aged in 1% NaCl for up to 1 year where after 80 restored and 12 unrestored teeth were subjected to an in vitro bacterial challenge for 36 days, the other 40 specimens were similarly incubated in an acidified broth (pH = 4.0). Sections were prepared for polarized light microscopy and outer and wall lesion areas, outer lesion width, wall lesion length and enamel thickness measured. Data were subjected to Fisher's exact test and Pearson Correlation. RESULTS: There was a significant association (P < 0.05) between outer and wall lesions in all cariously challenged specimen groups. Sensitivity was high 95-96% but specificity was 26% for acid broth, 68% for restored bacterial and 100% for unrestored specimens. Restoration variables impacted widely on specificity. Correlation values were too low to show clinically relevant associations between wall and outer lesion size. Frequency distribution showed that wall lesions extending beyond the dentin-enamel junction were generally associated with potentially remineralizable outer lesions.

Bicuspid↗

PubMed1997

Amalgam marginal quality assessment: a comparison of seven methods.

Black's class I classic cavities were cut in 120 sound extracted human premolars and restored with one of two silver amalgams, six different base combinations, with or without cavity varnish and then aged for 3 months or 1 year. Thereafter, the restored teeth were subjected to a bacterial or acid broth in vitro carious challenge for 36 days. Resin cast impressions were made of the restoration margin of each specimen before and after the carious challenge giving a total of 240 replicas. The replicas were examined in a scanning electron microscope (SEM) and the margins subjected to seven marginal assessment procedures: (i) ranking using micrographs of the margin; (ii) percentage length of marginal discrepancy; (iii) Mjor assessment using six groups; (iv) number of margin segments showing a discrepancy; (v) greatest gap size; (vi) ranking based firstly on gap size and then number of margin segments showing a discrepancy; and (vii) ranking based firstly on gap size and then percentage length of marginal discrepancy. The data from procedures (i), (ii), (vi) and (vii) were examined using one-way ANOVA; a linear logistic statistical analysis examined data from procedures (iii)-(v). Statistical significance was chosen at P < 0.05. It was found that procedure (vii) was able to discriminate between variables to a greater degree than all other procedures. It is recommended that a ranking system based on greatest gap size and percentage length of marginal discrepancy be used to assess marginal quality of amalgam restorations.

Analysis of Variance↗

PubMed1997

Marginal seal composition in amalgam restored teeth of varying marginal leakage.

An in vitro study was performed to ascertain the marginal seal elemental composition of amalgam restored extracted teeth of known marginal leakage. Occlusal cavities were cut in 400 caries free extracted teeth and left unlined or lined with one of 5 bases. A varnish was applied to half the cavities followed by restoration with a low copper or high copper amalgam to produce 20 restoration combinations. The teeth were stored in 1 per cent NaCl and thymol for 3 and 12 months at 20 degrees C whereafter a standard fluorescent dye marginal leakage test was performed on 320 specimens (eight teeth per treatment). Restoration combinations were grouped into 4 seal classes depending on percentage marginal seal achieved for each combination: 0-25 per cent; 26-50 per cent; 51-75 per cent and 76-100 per cent. The 80 remaining teeth (2 teeth per treatment) were fractured to expose the restoration and cavity surface, covered with marginal seal material and this was analysed by energy dispersive X-ray analysis. Elemental seal composition was compared to percentage marginal seal achieved using ANOVA and Tukey's test with significance set at p < 0.05. Numbers of elemental analysis specimens falling into each marginal seal class was 0-25 per cent = 48; 26-50 per cent = 18; 51-75 per cent = 10; 76-100 per cent = 4. Of the 16 elements detected, nine were significantly linked to sealing/leakage: Ca, Cl, Cu, Mg, Hg, P, Ag, Sn and Zn. The findings have a bearing on the improved longevity of amalgam restorations.

Analysis of Variance↗

PubMed1996

Effect of restorative materials and in vitro carious challenge on amalgam margin quality.

The surface margin of a restoration is where the restored tooth is subjected to aggressive oral attack. Any resistance to this attack will have favorable consequences on the clinical performance and longevity of the restoration. In this study, Black's class I classic cavity preparations were completed in 120 extracted intact human premolars that were restored with one of two silver amalgams, six different base conditions, and with or without cavity varnish, resulting in 20 different restoration combinations. The cavities were aged for 3 months and 1 year in 1% NaCl at 20 degrees C. A resin cast impression was made of the restoration margin for each specimen. Thereafter 80 restored teeth were subjected to an in vitro bacterial challenge for 36 days. The other 40 specimens were placed in an acidified (pH = 4.0) broth for the same length of time. A second cast impression was then made of the margin of each specimen. The casts were examined with a scanning electron microscope and the widest gap of the margin opening and the length of margin showing a discrepancy were measured. Specimens were ranked first on the basis of the gap size and then on percent of margin discrepancy length. Results were evaluated with one-way ANOVA and Turkey's Student range test with a critical level of statistical significance (p < 0.05). Base type significantly affected aged margin quality. Cariogenic challenge caused a significant breakdown of the amalgam margin although the type of challenge was not significant. A shorter aging time, varnish, and high copper amalgam exacerbated the breakdown. Margin breakdown can be reduced by judicious selection of restoration material combinations.

Analysis of Variance↗

PubMed1995

Amalgam restoration and in vitro caries formation.

Black's class I classic cavity preparations were completed in 124 extracted intact human premolars, of which 120 were restored with one of two silver amalgams, five different base combinations, and with or without cavity varnish. This resulted in 20 different restoration combinations. The other four teeth remained unrestored. Aging for 3 months and 1 year in 1% NaC1 at 20 degrees C followed. After aging, 80 of the restored teeth and the four unrestored teeth were subjected to an in vitro bacterial challenge for 36 days. The other 40 specimens were placed in an acidified (pH 4.0) broth for the same length of time. Sections were prepared for polarized light microscopy, and outer wall and dentin carious lesions were measured. The results were evaluated with one-way ANOVA and Tukey's Student range test with a critical level of statistical significance of p < 0.05 and p < 0.005. Lesions produced by bacterial challenge were significantly smaller than those formed by acidified broth. Aging time and varnish did not significantly influence lesion size. Low copper amalgam, a calcium hydroxide paste base, and restoration per se significantly reduced lesion size. Reproducible measurement of wall lesion length was not possible. Secondary caries lesion size can be minimized by judicious selection of restoration material combinations.

Acids↗