Validation of enamel erosion in vitro

Objectives

Many tools are available to quantify dental erosion, but each technique has its own inherent disadvantages. This study aims to validate the use of quantitative light-induced fluorescence (QLF) and non-contacting surface profilometry compared to the gold standard transverse microradiography (TMR) for the quantification of enamel erosion in vitro.

Methods

This was an in vitro laboratory based study. 60 bovine incisors were divided into 6 groups of 10. Each tooth's labial surface was completely varnished except for a window of enamel approximately 3 mm × 5 mm. Each was baseline imaged with QLF and non-contacting surface profilometry before being subjected to an erosive solution (pH 3.4) for up to 36 h. The lesions were imaged using non-contacting surface profilometry and QLF, sectioned and analysed with TMR. Correlation coefficients were calculated to assess the validity of the methods of measurement as compared to TMR.

Results

A range of lesion severities resulted. Mineral loss measured as ΔQ (QLF) and step height (profilometry), was recorded and confirmed by TMR. A correlation was found between ΔZ (TMR) and profilometry lesion depth of r = 0.648 (p < 0.001). A poorer correlation was found between ΔZ and ΔQ: r = 0.217 (p = 0.096).

Conclusions

Profilometry lesion depth and ΔZ correlated significantly. Both methods allow for quantification of erosive crater depth. QLF correlated poorly with ΔZ, but is useful for measuring subsurface loss of mineralisation. TMR is valuable but is destructive and can only be used in vitro. Currently only QLF can be used in vivo. Advances in these technologies may allow the development of non-destructive in vivo measurements of mineral loss, combining the positive features of each measurement method.     

Effect of fluoride-releasing restorative materials on bacteria-induced pH fall at the bacteria–material interface: An in vitro model study

Objectives

Inhibition of bacterial acid production by dental restorative materials is one of the strategies for secondary caries prevention. This study aimed to evaluate the effect of fluoride-releasing restorative materials on bacteria-induced pH fall at the bacteria–material interface.

Methods

Four fluoride-releasing restorative materials, glass-ionomer cement (GIC), resin-modified glass-ionomer cement (RMGIC), resin composite (RC) and flowable resin composite (FRC) were used. Each specimen was immersed in potassium phosphate buffer at pH 7.0 for 10 min and 4 weeks, and in potassium acetate buffer at pH 5.5 for 4 weeks. An experimental apparatus was made of polymethyl methacrylate and had a well with restorative materials or polymethyl methacrylate (control) at the bottom. The well was packed with cells of Streptococcus mutans, and the pH at the interface between cells and materials was monitored using a miniature pH electrode after the addition of 1% glucose for 90 min, and the fluoride released into the well was quantified using a fluoride ion electrode.

Results

The pH of GIC (4.98–5.18), RMGIC (4.77–4.99), RC (4.62–4.75) and FRC (4.54–4.84) at 90 min were higher than that of control (4.31–4.49). The fluoride amounts released from GIC were the highest, followed by RMGIC, RC and FRC, irrespective of immersion conditions. Saliva coating on materials had no significant effect.

Conclusions

The fluoride-releasing restorative materials inhibited pH fall at the bacteria–material interface. The degree of inhibition of pH fall seemed to correspond to the amount of fluoride detected, suggesting that the inhibition was due to the fluoride released from these materials.

Clinical significance

A little amount of fluoride actually released from the fluoride-releasing materials may have caries preventive potential for oral bacteria.     

The influence of different restorative materials on secondary caries development in situ

Objectives

The effect of direct restorative materials on caries lesion formation was investigated with an 8-week in situ study with split-mouth design, testing the hypothesis that no difference in mineral loss next to a restoration would be found between different composite-based-materials and amalgam.

Methods

Six groups (n = 18) of restored dentine samples were prepared using amalgam, a microhybrid, a nanohybrid and a silorane composite. The composites were adhesively bonded with systems with or without an antibacterial monomer (Clearfil-SE-Protect, Clearfil-SE-bond, respectively), except for the silorane group (Silorane-System-Adhesive). Non-restored dentine samples were used as control (primary caries). Samples were inserted into slots, in lower prosthesis especially made for the experiment. Subjects were instructed to dip the lower prosthesis in a sucrose solution 4 times per day. At baseline and 8 weeks, samples were radiographed extra-orally and the integrated mineral loss was calculated. Data were statistically analyzed using multiple linear regression with a multilevel model (p = 0.05).

Results

Nine subjects were selected, and only outer lesions were observed. The hypothesis was partially rejected, as the microhybrid composite bonded with the antibacterial system and the nanohybrid composite presented statistically significant lower mineral loss compared to amalgam. Also, no significant differences were seen for these groups compared to control.

Conclusion

Within the limits of this study, the restorative material may influence outer lesion progression. Amalgam was not found to be related to lower secondary caries progression in dentine compared to composite-based materials after 8 weeks in situ.

Clinical Significance

Although patient factors play a major role in caries progression, the restorative material may affect outer secondary lesion progression.     

Marginal adaptation of class II cavities restored with bulk-fill composites

Objectives

To determine the marginal adaptation of bulk-fill composites in class II MO cavities.

Methods

Standardized class II MO cavities with bevelled enamel margins were prepared in 40 extracted human molars. The teeth were randomly assigned to one of the five experimental groups (n = 8). The teeth were restored with two horizontal increments of composite (4 mm and 2 mm thickness). The experimental groups were (1st/2nd increment): Gr. A – Venus Bulk-Fill/Venus Diamond; Gr. B – Tetric EvoCeram BulkFill/Tetric EvoCeram; Gr. C – Surefil SDR/Ceram-X; Gr. D – SonicFill; Gr. E – Ceram-X/Ceram-X (control). After finishing procedures, impressions were made using a polyvinyl siloxane and epoxy resin replicas were obtained. Thermo-mechanical stressing was carried out 24 h after the restorative procedure. All specimens were submitted to 240,000 occlusal loading and simultaneous 600 thermal cycles in water at 5 °C and 50 °C. After loading, a new set of epoxy resin replicas was obtained. Scanning electron microscopy was carried out at 200× magnification. Results for the marginal adaptation were expressed as percentages of continuity relative to the exposed interface and analyzed by ANOVA and Duncan post hoc test (p < 0.05).

Results

In enamel, no significant differences were detected before and after thermo-mechanical loading between groups. In dentine, the worst results were observed in Gr. A.

Conclusion

By applying simple layering techniques, bulk-fill materials do not allow better marginal adaptation than a standard composite.

Clinical significance

A new class of resin-base composite (bulk-fill) was recently launched on the market. The bulk-fill composites exhibited adequate marginal adaptation and similar to the results of the standard composite.     

A prospective randomized clinical trial of one bis-GMA-based and two ormocer-based composite restorative systems in class II cavities: Five-year results

Objectives

Ormocer composites, consisting of a silicon-based polymer, have been developed recently as a tooth-colored restorative material. The purpose of this prospective randomized clinical trial was to evaluate the performance of two small-particle hybrid ormocer-based restorative systems (AD, Admira/Admira Bond, VOCO; DE, Definite/Etch & Prime 3.0, Dentsply) and one small-particle hybrid bis-GMA-based composite restorative system (TC, Tetric-Ceram/Syntac, Ivoclar-Vivadent) in class II cavities.

Methods

From 128 occlusal-proximal restorations (44 AD, 43 DE and 41 TC) placed in 32 adult patients, eventually 77 (22 AD, 29 DE and 26 TC) remained available for evaluation after 5 years. Their clinical performance was scored according to the USPHS criteria and evaluation of bite-wing radiographs.

Results

After 5 years, eight AD, six DE and seven TC restorations had failed (p = 0.10, log-rank test). The main reason was fracture or marginal gap formation, while secondary caries accounted for four failures. In all restorations the quality of surface, margins and contact point decreased significantly compared to baseline. DE had a significant poorer color match (p < 0.01). Statistical evaluation using the KW test showed that failures were concentrated on specific patients.

Conclusions

In a group of class II restorations, there was no significant difference in failures after 5 years between ormocer-based and bis-GMA-based restorative systems.     

Longevity of posterior restorations in primary teeth: Results from a paediatric dental clinic

Objectives

The aim of this retrospective study was to evaluate the longevity of restorations in the posterior primary teeth of children attending to a public paediatric dental clinic and to test the factors associated with failures.

Methods

Patient records of 329 children (162 boys and 166 girls) were used for collecting and analyzing data. A total of 565 restorations in primary teeth were included in the study. All children enrolled in the study were classified as high caries risk. The longevity of restorations from their placement until failure (up to 4 years of follow-up) was assessed using the Kaplan–Meier survival curves with log-rank test. Multivariate Cox regression analysis with shared frailty (p < 0.05) was used to assess the factors associated with failures.

Results

Up to 4 years of follow-up, the annual failure rates were 9.5% for composite fillings, 12.2% for light-cured glass ionomer restorations, and 12.9% for conventional glass ionomer restorations with statistical difference between the materials (p = 0.014). Glass ionomer restorations had a higher risk of failure over time compared with composites (HR 1.86, 95% CI 1.17–2.97). In crude analysis, Class II restorations showed lower survival rate than Class I restorations (p = 0.031) but lost significance after adjustments.

Conclusions

Our findings suggested that the material influenced the survival rate of primary posterior restorations, with composite presenting the best performance.

Clinical significance

Differences were observed between restorative materials with different properties in primary teeth up to 4 years of follow-up. This study provides valuable information regarding the primary teeth posterior restoration longevity in a paediatric population with restorations performed under daily life clinical environment.     

Intake of dairy products and the prevalence of dental caries in young children

Objectives

In vitro studies show that milk or milk components may have cariostatic properties. However, the results of epidemiological studies on the association between intake of dairy products and dental caries have been inconsistent. The purpose of this cross-sectional study was to examine the association between intake of dairy products and the prevalence of dental caries in young children.

Methods

Study subjects were 2058 Japanese children aged 3 years. Information on diet was assessed with a self-administered brief diet history questionnaire for children. The consumption of dairy products was categorized into 3 levels in order to represent the tertiles as closely as possible. Dental caries was assessed by a visual examination. Adjustment was made for sex, toothbrushing frequency, use of fluoride, between-meal snack frequency, maternal smoking during pregnancy, environmental tobacco smoke exposure at home, and paternal and maternal educational levels.

Results

Compared with yogurt consumption at the lowest tertile (<1 time/week), its intake at the highest level (≥4 times/week) was significantly associated with a lower prevalence of dental caries, showing a clear dose–response relationship (adjusted prevalence ratio = 0.78, 95% confidence interval: 0.62–0.98, P for trend = 0.04). There were no material associations between intake of cheese, bread and butter, or milk and the prevalence of dental caries.

Conclusions

These data suggest that a high consumption of yogurt may be associated with a lower prevalence of dental caries in young children.     

Comparison of sealant and infiltrant penetration into pit and fissure caries lesions in vitro

Objectives

The aim of this in vitro study was to evaluate the penetration of an infiltrant and a sealant, when applied as recommended, into fissure caries lesions.

Methods

The fissure systems of extracted human teeth were classified according to the international caries detection and assessment system (ICDAS, codes: 0, 1, 2). Within each ICDAS-code ten teeth were either etched with 37% H₃PO₄-gel for 60 s and subsequently sealed (‘Fissure Sealing’; Helioseal; Ivoclar Vivadent) or etched with 15% HCl-gel for 120 s and subsequently infiltrated (‘Resin Infiltration’; Icon; DMG). Additionally, ten teeth with ICDAS-code 2 were etched with 37% H₃PO₄-gel for 120 s and infiltrated (‘Soft-Etch-Infiltration’). Specimens were cut perpendicular to their surfaces, polished, and confocal microscopic images were obtained. Lesion depths (LD_max) and penetration depths (PD_max) were measured and percentage penetration was calculated as PP_max = PD_max/LD_max × 100.

Results

Baseline LD_max [median (interquartile range)] for ICDAS-code 2 lesions was 1192 (805–1512) μm. In ICDAS-code 2 lesions PP_max was significantly higher for specimens treated with ‘Resin Infiltration’ [41 (30–78)%] compared to ‘Soft-Etch-Infiltration’ [11 (0–21)%] or ‘Fissure Sealing’ [5 (0–9)%] (p < 0.05; Mann–Whitney test). PP_max did not differ significantly between groups in ICDAS-code 0 and 1 lesions (p > 0.05).

Conclusion

The fissure sealant when applied after etching with H₃PO₄-gel only penetrates superficially into non-cavitated fissure caries lesions. Penetration of an infiltrant is superior in particular after etching with HCl-gel.

Clinical significance

Compared with sealing, infiltration of fissure caries lesions leads to more deeply infiltrated lesions, which might in turn result in superior abilities to hamper caries progression.     

Reinforcement of dentin in self-etch adhesive technology: A new concept

Objective

Characterize the ultramorphology and secondary caries inhibition potential of different dentin adhesive systems in order to find a satisfactory explanation resist to recurrent caries.

Methods

Human premolar dentin was treated with one of the two self-etching adhesive systems, Clearfil SE Bond, Clearfil Protect Bond or an acid-etching adhesive system, Single Bond. The bonded interface was exposed to an artificial demineralizing solution (pH 4.5) for 90 min and then 5% sodium hypochlorite for 20 min. Transmission electron microscopic observation was performed at the adhesive–dentin interface. The width of the reinforced zone was measured and data were analyzed with univariate analysis of variance under general linear model. In order to identify type of crystallites in the reinforced zone selected area electron diffraction was performed.

Results

An acid–base resistant zone (ABRZ) was found adjacent to the hybrid layer in the outer lesion front with only Clearfil SE Bond and Clearfil Protect Bond, while Single Bond was devoid of this protective zone. Crystallite arrangement and the ultramorphology were almost similar in the corresponding regions of Clearfil SE Bond and Clearfil Protect Bond. However, thickness of the ABRZ at the mid portion was 1159(±41.91) nm in Clearfil protect Bond, which was significantly thicker than that of Clearfil SE Bond (F = 514.84, p < 0.001). Selected area electron diffraction confirmed the crystallites in the zone as apatite.

Conclusions

The self-etching adhesive systems created a new reinforced acid resistant dentin under the hybrid layer. Difference in the thickness of the zone expressed a different potential for demineralization inhibition.     

Occlusal caries: Evaluation of direct microscopy versus digital imaging used for two histological classification systems

Objective

Histology is frequently used as a gold standard to validate caries detection devices. Poor assessment consistency could lead to apparent changes in diagnostic accuracy. In multi-center, multi-examiner studies electronic transfer of information would be convenient, provided there is no deteriation in quality. This study tested the hypothesis that examiner reproducibility in the assessment of caries lesion depth when viewing photographic images of histological sections on a computer monitor, is comparable with viewing the same sections under a microscope using two histological classification systems.

Methods

166 investigation sites (96 teeth) were selected for visual examination (ICDAS-II) and sections made using a novel technique which reduced risk of section damage and allowed accurate allocation of section to each investigation site. Digital images of the sections were produced and four examiners viewed the sections under a microscope and on a separate occasion corresponding digital images on a computer monitor. Presence and extent of caries was scored according to two histological classification systems (Downer, ERK).

Results

The inter- and intra-examiner reproducibility for both histological classification systems and both examination techniques was substantial to almost perfect (weighted kappa = 0.63–0.90). Comparing the kappa values between microscopy and viewing digital images, there was no effect or only a small effect between both examination techniques (effect size 0.00–0.28). There was also a strong relationship between the two viewing techniques (r_s = 0.748–0.844).

Conclusions

Viewing digital images of tooth sections produces results comparable to viewing images directly under a microscope and therefore has potential benefits for multi-centre studies.     

Do socioeconomic determinants affect the quality of posterior dental restorations? A multilevel approach

Objectives

This study aimed to evaluate posterior restorations placed in young adults, investigating the association between social determinants experienced during the life course and the quality of tooth fillings.

Methods

A representative sample (n = 720) of all 5914 individuals who were born in Pelotas in 1982 was prospectively investigated, and posterior restorations were assessed at 24 years of age. Exploratory variables included demographic and socioeconomic, oral health and dental service payment mode during the life course. Tooth-related variables (type of tooth, material and size of cavity) were also analysed.

Results

Multilevel logistic regression models showed that individuals who were always poor from birth to age 23 [odds ratio (OR) 2.35 (1.38–4.00)] and whose mothers had less years of education at their birth (OR 2.60 (1.44–4.68)) were with unsatisfactory restorations in posterior teeth more often. In addition, caries presence at age 15 (high decayed, missing, filled teeth (DMFT) tertile) (OR 1.95 (1.25–3.03)) and cavities with four or more surfaces (OR 18.67 (9.25–37.68)) were associated with the outcome.

Conclusions

These results show that socioeconomic characteristics of the individuals play an important role in restoration failures, reinforcing the need for preventive dental strategies and public policies to reduce inequalities as a major topic of oral health. In addition, the size of cavity appears as the most important determinant for restoration failure.

Clinical significance

Individual socioeconomic characteristics were associated with failure in posterior restorations in detriment of other clinical variables such as restorative material and type of tooth.     

Effects of fluoride concentration on enamel demineralization kinetics in vitro

Objectives

The aim of the present study was to measure the effects of fluoride concentration on the real-time in vitro demineralization of enamel during exposure to caries-simulating conditions using Scanning Microradiography (SMR).

Methods

Enamel blocks obtained from non-carious human molars were fixed in SMR environmental cells, through which acidic solutions (0.1 M acetic acid, pH 4.0) were circulated for periods of 48 h. SMR was used to quantitatively measure continuous mineral mass loss. Subsequently, the effects of sequentially increasing fluoride concentration (0.1–4500 mg/L [F⁻]) in the acidic solutions were measured on the rate of enamel demineralization.

Results

The data shows a log-linear relationship between [F⁻] and reduction in demineralization up to 135 mg/L [F⁻]. Above 135 mg/L, no further significant decrease in demineralization occurred.

Conclusion

The optimum range of local fluoride concentration for reducing enamel demineralization was in the range 0.1–135 mg/L [F⁻] under the conditions studied.

Clinical significance

Relatively low [F⁻] can exhibit near-optimum protection. Increasing the fluoride concentrations above 135 mg/L may not necessarily give an increased cariostatic benefit. Improving the means of delivery of relatively low fluoride concentrations to the oral fluids through slow releasing mechanisms, such as the oral fluoride reservoirs, is the more appropriate way forward for sustaining long-term clinical efficacy.     

Clinical risk factors related to failures with zirconia-based restorations: An up to 9-year retrospective study

Objectives

The first objective of this study was to retrospectively evaluate zirconia-based restorations (ZBR). The second was to correlate failures with clinical parameters and to identify and to analyse chipping failures using fractographic analysis.

Methods

147 ZBR (tooth- and implant-supported crowns and fixed partial dentures (FPDs)) were evaluated after a mean observation period of 41.5 ± 31.8 months. Accessorily, zirconia implant abutments (n = 46) were also observed. The technical (USPHS criteria) and the biological outcomes of the ZBR were evaluated. Occlusal risk factors were examined: occlusal relationships, parafunctional habits, and the presence of occlusal nightguard. SEM fractographic analysis was performed using the intra-oral replica technique.

Results

The survival rate of crowns and FPDs was 93.2%, the success rate was 81.63% and the 9-year Kaplan–Meier estimated success rate was 52.66%. The chipping rate was 15% and the framework fracture rate was 2.7%. Most fractographic analyses revealed that veneer fractures originated from occlusal surface roughness. Several parameters were shown to significantly influence veneer fracture: the absence of occlusal nightguard (p = 0.0048), the presence of a ceramic restoration as an antagonist (p = 0.013), the presence of parafunctional activity (p = 0.018), and the presence of implants as support (p = 0.026). The implant abutments success rate was 100%.

Conclusions

The results of the present study confirm that chipping is the first cause of ZBR failure. They also underline the importance of clinical parameters in regards to the explanation of this complex problem. This issue should be considered in future prospective clinical studies.

Clinical significance

Practitioners can reduce chipping failures by taking into account several risk parameters, such as the presence of a ceramic restoration as an antagonist, the presence of parafunctional activity and the presence of implants as support. The use of an occlusal nightguard can also decrease failure rate.     

Comparison of Knoop and Vickers surface microhardness and transverse microradiography for the study of early caries lesion formation in human and bovine enamel

Objective

The aims of the present laboratory study were twofold: a) to investigate the suitability of Knoop and Vickers surface microhardness (SMH) in comparison to transverse microradiography (TMR) to investigate early enamel caries lesion formation; b) to compare the kinetics of caries lesion initiation and progression between human and bovine enamel.

Design

Specimens (90 × bovine and 90 × human enamel) were divided into six groups (demineralization times of 8/16/24/32/40/48 h) of 15 per enamel type and demineralized using a partially saturated lactic acid solution. SMH was measured before and after demineralization and changes in indentation length (ΔIL) calculated. Lesions were characterized using TMR. Data were analyzed (two-way ANOVA) and Pearson correlation coefficients calculated.

Results

ΔIL increased with increasing demineralization times but plateaued after 40 h, whereas lesion depth (L) and integrated mineral loss (ΔZ) increased almost linearly throughout. No differences between Knoop and Vickers SMH in their ability to measure enamel demineralization were observed as both correlated strongly. Overall, ΔIL correlated strongly with ΔZ and L but only moderately with the degree of surface zone mineralization, whereas ΔZ and L correlated strongly. Bovine demineralized faster than human enamel (all techniques).

Conclusions

Lesions in bovine formed faster than in human enamel, although the resulting lesions were almost indistinguishable in their mineral distribution characteristics. Early caries lesion demineralization can be sufficiently studied by SMH, but its limitations on the assessment of the mineral status of more demineralized lesions must be considered. Ideally, complementary techniques to assess changes in both physical and chemical lesion characteristics would be employed.     

Mineral distribution and CLSM analysis of secondary caries inhibition by fluoride/MDPB-containing adhesive system after cariogenic challenges

Objective

To evaluate the inhibition zone formation (IZ) and mineral distribution along the interface of adhesive systems either containing fluoride and antibacterial primer or not, after chemical and biological artificial caries challenges.

Methods

Forty-eight third molars were used. Artificial caries was developed with S. mutans in a 4 mm × 4 mm area of occlusal dentin surface. Carious dentin was removed and cavities were restored with Adper Scotchbond Multi-Purpose (SBM) and Clearfil Protect Bond (CPB) (n = 24). Samples were submitted to secondary caries development by chemical (C) (acidic gel) or biological (B) (S. mutans culture) methods for 5 days. Four groups were tested (n = 12): (1) SC (SBM + C); (2) SB (SBM + B); (3) CC (CPB + C); (4) CB (CPB + B). The IZ and outer lesion (OL) formations were analyzed by confocal laser scanning microscopy (CLSM). The distribution of calcium (Ca) and phosphorus (P) content along the interface was analyzed by micro X-ray fluorescence spectrometer by energy-dispersive (μEDX).

Results

The frequency of IZ formation and mean values of IZ thickness differed among the groups. The CC group presented the lowest OL depth. μEDX analysis showed that CPB had the highest mineral loss by the biological method, but the lowest mineral loss by the chemical method. SC and SB groups showed intermediate values of mineral loss.

Conclusion

The mineral loss along the dentin/restoration interface was affected by the artificial caries method, and hybrid layer formation by adhesive systems used. The adhesive system containing fluoride and antibacterial primer did not prevent secondary caries formation.     

Marginal integrity and secondary caries of selectively excavated teeth in vitro

Objectives

Selective caries removal involves sealing of carious dentine beneath restorations, which might decrease their marginal integrity and increase the susceptibility for secondary caries and microleakage. The present study compared these marginal characteristics of restorations in selectively and completely excavated teeth.

Methods

In 32 premolars, shallow and deep artificial lesions were created on pulpo-axial walls of mesial-distal-occlusal cavities, with mesial and distal margins located in enamel and dentine, respectively. Demineralised dentine was either removed or left before adhesively restoring the teeth (n = 8), which were then submitted to thermo-mechanical cycling. The integrity of gingivo-cervical margins was assessed using scanning electron microscopy. In half of each margin, caries was induced adjacent to restorations using a continuous-culture biofilm model, and resulting lesions were evaluated using transversal microradiography. The other half of each margin was used to assess microleakage.

Results

Integrity or microleakage of margins located in enamel did not differ significantly between groups, and bacterial biofilms did not induce distinct caries lesions in enamel. Dentinal margins in teeth with deep compared with shallow lesions showed a significantly higher proportion of marginal imperfections, gaps and microleakage (p ≤ 0.05, Mann–Whitney/χ²-test). In contrast, neither marginal integrity nor microleakage differed significantly between completely and selectively excavated teeth (p > 0.05). Dentinal mineral loss adjacent to restorations did not differ significantly between groups (p > 0.80).

Conclusions

The marginal characteristics of restorations were affected by the depth of sealed or excavated lesions, but not by the performed caries excavation. This study did not find selective excavation detrimental for restoration integrity in vitro.

Clinical significance

Selective excavation of deep lesions was shown to reduce pulpal risks, whilst leaving caries beneath restorations is feared to compromise the marginal characteristics of the subsequently placed restoration. Based on the present in vitro study, such assumptions cannot be supported.     

Caries-preventive effectiveness of fluoride varnish as adjunct to oral health promotion and supervised tooth brushing in preschool children: A double-blind randomized controlled trial

Objectives

To evaluate the effect of biannual fluoride varnish applications in preschool children as an adjunct to school-based oral health promotion and supervised tooth brushing with 1000 ppm fluoride toothpaste.

Methods

424 preschool children, 2–5 year of age, from 10 different pre schools in Athens were invited to this double-blind randomized controlled trial and 328 children completed the 2-year programme. All children received oral health education with hygiene instructions twice yearly and attended supervised tooth brushing once daily. The test group was treated with fluoride varnish (0.9% diflurosilane) biannually while the control group had placebo applications. The primary endpoints were caries prevalence and increment; secondary outcomes were gingival health, mutans streptococci growth and salivary buffer capacity.

Results

The groups were balanced at baseline and no significant differences in caries prevalence or increment were displayed between the groups after 1 and 2 years, respectively. There was a reduced number of new pre-cavitated enamel lesions during the second year of the study (p = 0.05) but the decrease was not statistically significant. The secondary endpoints were unaffected by the varnish treatments.

Conclusions

Under the present conditions, biannual fluoride varnish applications in preschool children did not show significant caries-preventive benefits when provided as an adjunct to school-based supervised tooth brushing with 1000 ppm fluoride toothpaste.

Clinical significance

In community based, caries prevention programmes, for high caries risk preschool children, a fluoride varnish may add little to caries prevention, when 1000 ppm fluoride toothpaste is used daily.     

The association between dental wear and reduced vertical dimension of the face: A morphologic study on human skulls

Objective

The aim of this study was to explore the relationship between dental wear and facial morphology, with particular reference to the occlusal vertical dimension, in modern human skulls.

Design

One hundred and three skulls (52 men and 51 women) between the ages of 20 and 50+ years old were studied. The selected skulls were from a modern period (the 17th and the 18th centuries) and included at least one entire condyle and had at least 3 posterior teeth (premolar or molar) in each quadrant to allow for dental articulation. Occlusal wear was evaluated using ordinal scale (0–4) and vertical occlusal dimension was evaluated by measuring upper facial height (UFH), lower facial height (LFH), LFH-to-UFH ratio (L-U-R) and dental wear. Based on the occlusal wear score, two groups were defined: with and without significant wear.

Results

Significant relation was observed between age and dental wear (P < 0.01). No significant differences were found in the LFH (P = 0.847) or UFH (P = 0.108) between the two wear groups. In addition, no significant difference (P = 0.132) was demonstrated in the LFH-to-UFH ratio between the groups. No difference was observed in the dental wear score between genders (P = 0.321).

Conclusion

Within its limitations, this study demonstrated that dental wear does not influence the vertical dimension of occlusion. Our assumption is that the dento-facial complex fully compensates for the dental effects of wear throughout life.     

Comparison of pattern of failure of resin composite restorations in non-carious cervical lesions with and without occlusal wear facets

Objectives

Many studies have reported the clinical problems associated with resin composite restorations in NCCLs. None has compared these clinical problems in NCCLs with and without occlusal wear facets. The present study sets out to determine the proportion of NCCLs that presents occlusal wear facets, and to compare the failure pattern of resin composite restorations in NCCLs with and without occlusal wear facets.

Methods

Teeth with NCCLs were classified into two groups, those with and without occlusal wear facets. Both groups were restored using micro hybrid resin composite. The restorations were evaluated at the end of 2 years concerning post-operative sensitivity, retention, marginal integrity, marginal discolouration, wear, and secondary caries, using the USPHS criteria. Statistical analysis compared the ratings of each criterion between the two groups using Pearson's χ² or Fisher's exact test.

Results

About one-third (33.8%) of teeth with NCCLs presented with occlusal wear facets, more NCCLs with occlusal wear facets in mandibular teeth (44.7%) than maxillary teeth (24.5%). Retention rate of composite resin restorations in NCCLs with and without occlusal wear facets was 63.9% and 74.4% respectively at the end of 2 years. More marginal discolouration and defects were observed in restorations in NCCLs with occlusal wear facets, the differences were not statistically significant (p > 0.05).

Conclusions

The decline in ratings of marginal discolouration and defects, and the lower retention rate of restorations in NCCLs with occlusal wear facets may support the role of occlusal stress and tooth flexure as a cause of failure of restorations in NCCLs.

Clinical significance

The ability to distinguish between stress induced lesions (with occlusal wear facets) and other cervical lesions will have important ramifications for the success of their restorations because they are not subjected to the same physical forces that are responsible for the deterioration of the restoration.     

Randomized multi-centre study on the effect of training on tooth shade matching

Objectives

The aim of this study was to find out whether Toothguide Trainer, TT, and Toothguide Training Box, TTB, show any training effects, independent of the shade guide chosen.

Methods

Students from four dental schools (N = 78) were included in this study. The participants were randomized into a study, 42 students (age range: 19–27 years; 69% female, 31% male) and a control group of 36 students (age range: 19–30 years; 57% female, 43% male). The study group started with a double blind introduction test, followed by the TT and TTB training, finishing with the final test. The control group only passed the introduction and – after a break – the final test. Eight randomly chosen samples, seven of the Vita classical and one of the 3D-Master colour scale, were marked by barcodes. Colour matching was arranged by the Vita classical scale.

Results

The results of the pre- and final tests of both groups were combined. For every sample, the value ΔE was determined. The summation of all eight samples from the introduction and final tests offered a summarized ΔE value. The differences between introduction and final tests revealed the individual learning success. 47.6% of the study group showed statistically significant better results than the control group, 33% (p = 0.031).

Conclusion

TT and TTB show a positive effect of training on tooth shade matching independent of the colour scale used.

Clinical significance

Visual shade taking is the most frequent clinical method for shade determination. To increase better results in visual colour matching, TT and TTB training is used. This is the first study examining the training effect of TT and TTB using Vita classical scale.