Abstract
Objectives
An evaluation method is proposed to qualitatively and quantitatively evaluate the clinical outcome of the enamel hypomineralization treatment with infiltrative resin in young adolescents. The aesthetic outcome is assessed before and after treatment by visual evaluation using FDI-colour match criteria and by spectrophotometric analysis using the CIEDE2000 colour difference formula. The visual (subjective) results are compared with the spectrophotometric (objective) approach.
Materials and methods
76 teeth of patients of Sapienza University (Rome, Italy) presenting early caries lesions and/or developmental defect of enamel on the labial surface of clinical crown were subjected to resin infiltration. Three observers evaluated the aesthetic appearance of the teeth before and after treatment using FDI-colour match criteria. The spectrophotometric colour difference between the affected and sound enamel in each tooth was calculated before and after resin infiltration. A correlation between FDI criteria and the calculated CIEDE2000 colour difference (ΔE 00 ) was performed.
Results
Mean FDI scores and ΔE 00 , evaluated before and after treatment, were large in all sample. A clear correlation was detected between visual inspections and spectrophotometric colour difference of clinical outcomes.
Conclusions
On the basis of the present study results, the aesthetic outcome of resin infiltration proved to be highly effective, both with visual qualitative and spectrophotometric quantitative assessment.
Clinical relevance statement
Hypomineralized enamel colour abnormalities affect patients’ quality of life, therefore tissue preservative cosmetic treatments are requested. An evaluation method of resin infiltration clinical outcome by visual evaluation and spectrophotometry is proposed.
1
Introduction
Early Caries Lesions (ECLs), developmental defects of enamel (DDE), traumatic hypomineralization and molar incisal hypomineralization (MIH) are all characterized by enamel hypomineralization . Hypomineralized enamel may involve pre-eruptive or post-eruptive etiologies. The most common pre-eruptive etiologies are fluorosis, coeliac disease and malabsorption disorders, traumatic hypomineralization and MIH, while ECLs are the most common lesions with post-eruptive etiological factors . Clinical management of enamel hypomineralization is challenging and patients with aesthetic concerns more often require tissue preservation and minimally invasive treatment of tooth colour abnormalities.
Until recently, fluoride or caseine phosphopeptide treatments have been used . However, the outcomes are often hampered by lack of patient compliance which can be a particular concern with adolescents. Moreover, the aesthetic effect is usually not satisfactory . To overcome these limitations, a new minimally invasive treatment has recently been proposed that utilizes resin infiltration, a product first developed to halt caries in the posterior segment . This treatment involves superficial demineralization by application of a 15% solution of hydrochloric acid, which opens up access to the hypomineralized site that can then be infiltrated by a fluid resin. Resin infiltration has been reported to improve aesthetic effect by increasing the refractive index of the lesion, which consequently takes on the appearance of the surrounding sound enamel with restoration of the enamel translucence .
A recent in vitro study on 30 extracted human teeth compared, for the first time, both quantitative and qualitative tooth-surface aesthetic properties before and after resin infiltrantion . A significant improvement in colour, reverting ECLs colorimetrically altered values back toward the surrounding unaffected enamel, was observed. However, available data on quantitative and qualitative assessment of this newly proposed treatment for hypomineralized enamel lesions in humans are scarce .
The primary and secondary aims of the present study were to retrospectively evaluate in a cohort of young adolescents: (1) the effect of infiltrative resin treatment on hypomineralized enamel lesions by means of FDI score change before and after treatment; the measurement of the existing colour difference ΔE 00 between the affected and the sound enamel for each tooth, before and after treatment, by calculating CIEDE2000 colour differences; (2) the correlation between the qualitative FDI-scores and the quantitative ΔE 00 colour difference.
2
Materials and methods
2.1
Patients
All consecutive patients with hypomineralized enamel lesions on labial surface due to ECLs and/or DDE who, between September 2015 and November 2015, underwent treatment using resin infiltration were retrospectively retrieved from our prospectively maintained institutional database.
Inclusion criteria were ECLs and DDE. Exclusion criteria were MIH.
The study was approved by the local ethical committee and informed consent was obtained from all patients.
2.2
Definition of hypomineralized lesions
Early caries lesions were defined as opaque, matte, chalky white areas, and as having a whitish halo located around the orthodontic brackets.
Developmental defect of enamel was defined as defects of different colours (white/cream and yellow/brown), which can appear as demarcated or diffuse opacities, lines or patchy, diffuse confluent opacities, or a combination of the previous features, or frankly hypoplastic, with symmetrical involvement of groups of homologous teeth .
2.3
Infiltrative resin treatment procedure
Trained operators performed resin infiltration. Teeth were cleaned, a rubber dam was placed and resin infiltration was performed according to the manufacturer’s indications. Treated lesions were etched for 2 min with 15% hydrochloric acid (Icon Etch, DMG) and then rinsed with air-water spray for 30 s. Dessication of the lesions by air blowing for 10 s, followed by application of ethanol (Icon Dry, DMG, Hamburg, Germany) for 30 s, and air blowing again for 10 s was then performed. Application of the infiltrant resin (Icon Infiltrant, DMG) to the lesion under treatment was performed with a sponge applicator provided by the resin infiltration system that was then left in place for 3 min. The excess resin was subsequently removed with air spray and flossed and light-cured for 40 s. The resin infiltration step was repeated a second time with a penetration time of 60 s to allow resin to infiltrate the remaining porosities and light-cured for additional 40 s.
2.4
Qualitative visual evaluation
Visual assessments were made on digital photographs (Nikon D7100, 105 mm Macro lens, R1C1 Macro flash) that were taken before and after the resin infiltration procedure. A representative case is shown in Fig. 1 . We used standardized camera settings (shutter speed 1/80 and aperture settings f44). Moreover, the same lighting conditions for capturing all digital photographs were employed. The digital images were viewed on a display that was configured to have a CIE D65 (daylight) white point. A formal colour characterization of the imaging setup was not carried out. However, the visual assessments that were made were relative and the before and after images were viewed after being subjected to the same imaging workflow.
Three trained operators with skills in cosmetic dentistry performed the qualitative visual evaluation at T 0 (before treatment) and at T 1 (after treatment) by assessing the change of the FDI-colour match criteria score on before and after treatment images. Qualitative visual evaluation was performed by applying the Fédération Dentaire Internationale (FDI) approved clinical aesthetic colour match and translucency criteria Evaluation scale:
- 1.
Clinically excellent/very good (Good colour match. No difference in shade and translucency);
- 2.
Clinically good (Minor deviations);
- 3.
Clinically sufficient/satisfactory (Clear deviation but acceptable. Does not affect aesthetics);
- 4.
Clinically unsatisfactory (Localised-clinically unsatisfactory, but can be corrected by repair);
- 5.
Clinically poor (Unacceptable. Replacement necessary.) .
According to this ranking, five scores were used to qualitatively assess the colour match of the affected and sound enamel per each tooth before and after treatment.
2.5
Quantitative spectrophotometric evaluation and measurements
Quantitative evaluation was performed using a calibrated reflectance spectrophotometer (SpectroShade, MICRO, Serial N HDL1407, MHT, Arbizzano di Negrar, Verona, Italy). Spectrophotometric technical functioning and operative procedures were conducted as described in a previous study . The device was positioned perpendicularly to the labial surface of the clinical crown until a green line appeared on the device’s screen to indicate the correct position for obtaining reproducible measurements. Spectral reflectance factors were measured at intervals of 8 nm and the on-board software of the MHT instrument calculated CIE (1976) L*a*b* colour coordinates for specific tooth areas.
Spectrophotometric measurements before and after treatment were performed against a black background (L* = 1.6, a* = 1.2, b* = −1.0) that was positioned behind the tooth. To define the effect of treatment in relation to the extent of the lesion under treatment, two measurement points (sound and affected enamel) were chosen to calculate the colour difference, before and after resin infiltration (see Fig. 1 ).
The colour change between before and after resin infiltration for each tooth was defined by the CIEDE2000 colour space , known as ΔE 00 , which more perceptually uniform that the older CIELAB colour difference.
2.6
Statistical analysis
The R software program (R Foundation for Statistical Computing, Vienna, Austria, ver. 3.2.2) was used for the statistical analyses. A paired t -test was used to compare the means of FDI scores and ΔE 00 values, testing the null hypothesis that the average of the differences between the series of paired observation is zero.
The correlation between visual and spectrophotometric measurements was investigated by using the Pearson correlation coefficient statistic as a measure of the linear correlation between two variables. It ranges from −1 to +1, where 1 indicates a perfect linear correlation and 0 indicates no linear correlation.
2
Materials and methods
2.1
Patients
All consecutive patients with hypomineralized enamel lesions on labial surface due to ECLs and/or DDE who, between September 2015 and November 2015, underwent treatment using resin infiltration were retrospectively retrieved from our prospectively maintained institutional database.
Inclusion criteria were ECLs and DDE. Exclusion criteria were MIH.
The study was approved by the local ethical committee and informed consent was obtained from all patients.
2.2
Definition of hypomineralized lesions
Early caries lesions were defined as opaque, matte, chalky white areas, and as having a whitish halo located around the orthodontic brackets.
Developmental defect of enamel was defined as defects of different colours (white/cream and yellow/brown), which can appear as demarcated or diffuse opacities, lines or patchy, diffuse confluent opacities, or a combination of the previous features, or frankly hypoplastic, with symmetrical involvement of groups of homologous teeth .
2.3
Infiltrative resin treatment procedure
Trained operators performed resin infiltration. Teeth were cleaned, a rubber dam was placed and resin infiltration was performed according to the manufacturer’s indications. Treated lesions were etched for 2 min with 15% hydrochloric acid (Icon Etch, DMG) and then rinsed with air-water spray for 30 s. Dessication of the lesions by air blowing for 10 s, followed by application of ethanol (Icon Dry, DMG, Hamburg, Germany) for 30 s, and air blowing again for 10 s was then performed. Application of the infiltrant resin (Icon Infiltrant, DMG) to the lesion under treatment was performed with a sponge applicator provided by the resin infiltration system that was then left in place for 3 min. The excess resin was subsequently removed with air spray and flossed and light-cured for 40 s. The resin infiltration step was repeated a second time with a penetration time of 60 s to allow resin to infiltrate the remaining porosities and light-cured for additional 40 s.
2.4
Qualitative visual evaluation
Visual assessments were made on digital photographs (Nikon D7100, 105 mm Macro lens, R1C1 Macro flash) that were taken before and after the resin infiltration procedure. A representative case is shown in Fig. 1 . We used standardized camera settings (shutter speed 1/80 and aperture settings f44). Moreover, the same lighting conditions for capturing all digital photographs were employed. The digital images were viewed on a display that was configured to have a CIE D65 (daylight) white point. A formal colour characterization of the imaging setup was not carried out. However, the visual assessments that were made were relative and the before and after images were viewed after being subjected to the same imaging workflow.
Three trained operators with skills in cosmetic dentistry performed the qualitative visual evaluation at T 0 (before treatment) and at T 1 (after treatment) by assessing the change of the FDI-colour match criteria score on before and after treatment images. Qualitative visual evaluation was performed by applying the Fédération Dentaire Internationale (FDI) approved clinical aesthetic colour match and translucency criteria Evaluation scale:
- 1.
Clinically excellent/very good (Good colour match. No difference in shade and translucency);
- 2.
Clinically good (Minor deviations);
- 3.
Clinically sufficient/satisfactory (Clear deviation but acceptable. Does not affect aesthetics);
- 4.
Clinically unsatisfactory (Localised-clinically unsatisfactory, but can be corrected by repair);
- 5.
Clinically poor (Unacceptable. Replacement necessary.) .
According to this ranking, five scores were used to qualitatively assess the colour match of the affected and sound enamel per each tooth before and after treatment.
2.5
Quantitative spectrophotometric evaluation and measurements
Quantitative evaluation was performed using a calibrated reflectance spectrophotometer (SpectroShade, MICRO, Serial N HDL1407, MHT, Arbizzano di Negrar, Verona, Italy). Spectrophotometric technical functioning and operative procedures were conducted as described in a previous study . The device was positioned perpendicularly to the labial surface of the clinical crown until a green line appeared on the device’s screen to indicate the correct position for obtaining reproducible measurements. Spectral reflectance factors were measured at intervals of 8 nm and the on-board software of the MHT instrument calculated CIE (1976) L*a*b* colour coordinates for specific tooth areas.
Spectrophotometric measurements before and after treatment were performed against a black background (L* = 1.6, a* = 1.2, b* = −1.0) that was positioned behind the tooth. To define the effect of treatment in relation to the extent of the lesion under treatment, two measurement points (sound and affected enamel) were chosen to calculate the colour difference, before and after resin infiltration (see Fig. 1 ).
The colour change between before and after resin infiltration for each tooth was defined by the CIEDE2000 colour space , known as ΔE 00 , which more perceptually uniform that the older CIELAB colour difference.
2.6
Statistical analysis
The R software program (R Foundation for Statistical Computing, Vienna, Austria, ver. 3.2.2) was used for the statistical analyses. A paired t -test was used to compare the means of FDI scores and ΔE 00 values, testing the null hypothesis that the average of the differences between the series of paired observation is zero.
The correlation between visual and spectrophotometric measurements was investigated by using the Pearson correlation coefficient statistic as a measure of the linear correlation between two variables. It ranges from −1 to +1, where 1 indicates a perfect linear correlation and 0 indicates no linear correlation.
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