Evaluation of the effect of surface preparation using phosphoric acid and luting cement on the flexural strength of porcelain laminate veneering material

The Effect of Different Surface Conditioning Techniques on the Bonding between Resin Cement & Ceramic

Surface etching before cementation is a vital step that determines the clinical performance of ceramic restorations. Etching alters surface topography that contributes effective bonding between ceramic restoration and resin cement. This study aimed to compare etching techniques to determine the most effective etching method contributing the highest bond strength that helps in improving dental implants. Materials and methods: sixty discs of feldspathic ceramic measuring 10 mm diameter and 4 mm thickness were prepared. The 60 samples were divided into four equal groups based on the surface treatment technique used: group A: 9.6% hydrofluoric acid; group B: coarse diamond burs; group C: CO2 laser; and group D: no treatment. Ceramic disc specimens were examined under a Scanning Electron microscope (SEM) after surface treatment to characterize their surface morphology. Further, the specimens were luted with a resin luting agent and incubated for 24 h at a temperature of 37 °C simulating the oral environment. After 24 h, shear bond strength (SBS) and the nature of bond failure was determined for each specimen using a universal Instron testing machine. Results: significant change in surface morphology was noticed on hydrofluoric acid treatment forming larger irregular roughness (4.83 ± 1.78 µm) with multiple patterns of grooves and pores compared to other groups. Further, the highest SBS value was measured on hydrofluoric acid etching that display the highest bond strength due to the high surface roughness. In conclusion, our findings report a strong association between the surface roughness and bond strength upon hydrofluoric acid compared to other methods. Further work in this direction will enhance the utility of the etching technique on the improvement of dental implants.

Erbium-Doped, Yttrium-Aluminum-Garnet Laser Debonding of Porcelain Laminate Veneers: An Ex vivo Study

Background:

The use of ceramic laminate veneer has considerably and successfully grown to improve anterior tooth esthetics in recent years. The removal of ceramic laminate veneers with laser is reported only in a scanty number of publications and for this reason the importance and the aim of this ex vivo study consist to verify the ability of Er: YAG laser for laminate veneers debonding with the preserving of the tooth structures (scanning electron microscopy [SEM] observations).

Aim:

The purpose of this study consists to verify if erbium-doped, yttrium-aluminum-garnet (Er:YAG) laser, at low fluences, is able to debond porcelain veneers, successfully used to improve anterior tooth esthetics, without damaging the tooth structures.

Settings and Design:

A total of 12 freshly extracted teeth were used, and samples were decontaminated, stored, and bonded to obtain veneers adhesion. One week after, Er:YAG laser with a non-contact sapphire tip with air-water spray was used for veneer debonding at 100 mJ of energy and 30 Hz of frequency (Fluence 19.94 J/cm²).

Results:

Results demonstrated that veneer debonding is possible with an Er:YAG laser and the total number of pulses seems not related to its efficiency. SEM observation confirms that residual tooth structure is not altered when using these low fluences.

Conclusions:

Low fluences with Er:YAG laser are able to debond veneers while preserving the tooth structures and SEM observation confirmed that residual tooth structure is not altered with low fluences.