A scanning electron and confocal laser microscope investigation of tetracycline-affected human dentine

Masking ability of different ceramics upon various underlying structures

OBJECTIVE

To evaluate masking ability of different types and thicknesses of ceramics upon various substructures.

MATERIALS AND METHODS

Discs (Ø 12 mm, thickness 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, and 2.0 mm) were prepared from Bruxzir-Anterior® (Bc), Celtra-DUO® (Cc), and Vita-Suprinity® (Vc) (n = 15/group). Substructures (2 mm thickness) were prepared from natural dentine (Ds), tetracycline-stained dentine (Ts), zirconia (Zs), resin composite (Rs), and cast metal (Ms). A spectrophotometer was used to measure the CIE L*a*b* color coordinates of a specimen. Masking ability was determined from the color difference (∆E₀₀ ) of ceramics between before- and after combining with substructure using ANOVA and Bonferroni test (α = 0.05). ∆E₀₀ value was compared with acceptable clinical threshold (∆E₀₀  = 1.8) and an ideal threshold (∆E₀₀  = 0.8).

RESULTS

Type-thickness of ceramics and substructures were significantly affected ∆E₀₀ . Ts significantly influenced ∆E₀₀ more than Rs, Ms, Zs, and Ds. No significant ∆E₀₀ upon Ms and Zs was indicated. Bc completely masked Ts and Rs if thickness was ≥0.6 mm, and Zs, Ms, and Ds if ≥0.4 mm. Cc completely masked Ts and Rs if thickness was >1.6 mm, and Zs, Ms, and Ds if >1.4 mm. Vc completely masked Ts if thickness was >1.4 mm, Rs and Ms if >1.2 mm, and Zs and Ds if >1 mm.

CONCLUSION

Ts is the most influential substructure impact on color appearance, requiring a minimum thickness of 0.6 mm Bc, 1.2 mm Vc, or 1.6 mm Cc to be perfectly masked.

CLINICAL SIGNIFICANCE

Masking ability was significantly influenced by the type and thickness of ceramic material and underlying structure. Monolithic zirconia had a significantly higher masking ability than lithium silicate/phosphate glass ceramic. Ts indicated the most influencial substructure impacting the color appearance of ceramic restoration, which require a minimum thickness of 0.6 mm Bc, 1.2 mm Vc, or 1.6 mm Cc to achieve ideal masking capability.

Determination of crown discoloration and fluorescence induced by different medications used in regenerative endodontic procedures: An ex vivo study

Background

Crown discoloration is an undesirable side effect of the use of triple antibiotic paste (TAP) in regenerative endodontic procedures (REPs). The aim of this ex vivo study was to assess the potential for tooth discoloration and induction of fluorescence associated with the use of TAP containing either doxycycline (DOX) or clindamycin (CLIN), and of calcium hydroxide (Ca(OH)2), by spectrophotometric analysis and confocal laser scanning microscopy (CLSM).

Material and Methods

A total of forty single-rooted human teeth extracted by therapeutic indication were used. The root canals were enlarged using the step-back technique up to a K #80 file and were randomly divided into four experimental groups (10 specimens each): i)Ca(OH)2 group, ii)TAP with DOX group, iii) TAP with CLIN group, iv) Control group (no treatment). To quantify the change of color of the different groups of teeth included, the Vita Easyshade advance 4.0 spectrophotometer was used. CLSM was used to determine fluorescence.

Results

After 28 days of action inside the root canal, no extreme discoloration was visible, to the naked eye, in any of the teeth included in the study. Under the conditions of this ex vivo study, TAP with DOX induced the highest crown discoloration among the medicaments tested. In contrast, Ca(OH)2 and TAP with CLIN did not induce crown discoloration after 28 days. The TAP with DOX group presented the highest fluorescence measurements.

Conclusions

Considering the discoloration potential and fluorescence changes in TAP with DOX or other tetracyclines, and the cytotoxic effect of TAPs, we recommend the use of Ca(OH)2 for REPs.

Key words:Discoloration, doxycycline, clinadamycin, calcium hydroxide, endodontics.

Splinted Porcelain Laminate Veneers With a Natural Tooth Pontic: A Provisional Approach for Conservative and Esthetic Treatment of a Challenging Case

Esthetic rehabilitation of discolored anterior teeth is always a great challenge, especially in the presence of pathology. Fortunately, conservative management in the esthetic zone has become more feasible in compromised cases because of the development of restorative materials and advances in dental adhesives. This report presents a complicated case of a patient with tetracycline-related discoloration, multiple root resorption, and a periapical lesion. Treatment was conservative and used a natural tooth pontic and splinted porcelain laminate veneers.