Tooth whitening: A conservative approach

Sensitivity of the tooth and irritation of the gingiva are common during tooth whitening; however, all side effects cease upon completion of treatment. Nevertheless, a comprehensive examination followed by proper consultation is required to meet the patient’s aesthetic expectations with an emphasis on maximum
conservation of healthy dental tissue.

Case report

In many cases, patients are well aware of their dental problems and request specific dental treatment. In this case, a 33-year-old female patient wished for tooth whitening and re-contouring of her prominent upper canines.

A comprehensive examination and smile analysis using a spectrophotometer (Spectroshade, MHT) revealed healthy dentition with a shade range between D4 and A4 (Fig. 1).

Fig. 1: Smile analysis before whitening.

The upper right first premolar presented a cervical abfraction area with moderate sensitivity to cold. The left first premolar had a Class V composite resin filling with slightly worn margins. Localised white decalcification areas were visible on the upper lateral incisors (Fig. 2).

Tooth whitening, aesthetic re-contouring of the upper cuspids, and a Class V composite resin filling on the right first premolar were proposed to the patient. The possibility of additional treatment of the upper lateral incisors was given in case the white decalcification areas would not blend in naturally with the whitened teeth.

Tooth whitening can be performed either at home with the use of a relatively low concentration of whitening agent delivered in a custom-fabricated tray or in the office with higher concentrations of hydrogen peroxide and a resin barrier to prevent the gel from irritating the soft tissue. Generally, the use of light activation to accelerate the procedure is optional.

In order to obtain a favourable result in a relatively short time, the patient preferred a combination of home and power whitening. An alginate impression was taken prior to the first in-office whitening session (Fig. 3). While the patient received whitening of the upper arch for 40 minutes, a model was poured and a customised tray was fabricated. Thus, it was possible to deliver the upper tray and the home whitening kit on the day of treatment.

Routine explanations on the possibility of sensitivity to cold, irritation to the gingiva, and limitation of whitening in the cervical area were given to the patient. The patient was scheduled for her second inoffice whitening session with an interval of three to four days. During that time, home whitening was performed for maximum efficacy of the treatment. After the third in-office whitening session, a remarkable difference was observed between the upper and lower teeth (Fig. 4). Although the decalcification area on the left lateral incisor was slightly more noticeable at this stage, the patient was very happy about the distinct colour difference between the upper and lower teeth. Treatment on the lower teeth was conducted in the same manner as the upper teeth. She received three in-office whitening sessions on the lower arch with an interval of three to four days combined with home whitening.

Figs. 2–5: Intra-oral view before whitening (Fig. 2). Power whitening with a light-activating device (Fig. 3). Distinct colour difference between the upper and lower teeth (Fig. 4). Intra-oral view after whitening (Fig. 5).

Aesthetic re-contouring was cautiously performed with 12-fluted carbide burs to reduce the tips of the cuspids. The Class V composite resin filling was placed two weeks after whitening to allow for colour stability and recovery of bond strength of the enamel. At this stage, the decalcification area finally blended in naturally with the whitened teeth (Fig. 5).

A smile analysis after treatment revealed the efficacy of tooth whitening and confirmed that the treatment had been completed successfully (Fig. 6).

Fig. 6: Smile analysis after whitening.

Shade changes can be measured as shade guide units on a value-oriented, classic vita shade guide or as ΔE values defined by the Commission Internationale de l’Éclairage (CIE) L*a*b* colour system. ΔE is the shortest distance in the CIE L*a*b* colour space between the colours being compared and is determined using the equation ΔE= (ΔL*2 + Δa*2 + Δb*2)1/2 where L* represents lightness, a* corresponds to the red–green axis (positive value indicates red, negative indicates green), and b* corresponds to the yellow–blue axis (positive value indicates yellow, negative value indicates blue). The shade change as indicated by ΔE was obtained by overlapping the image of the same tooth before and after tooth whitening (Fig. 7), using the Spectroshade analysis software (Version 2.41).

An increase in ΔE after tooth whitening is usually attributed to an increase in L* values and a decrease in b* values. It is interesting to note that ΔE values varied according to the teeth although all teeth were treated with the same concentration and same exposure time. This suggests that each tooth has its own degree of whitening, which is a very important factor that influences the efficacy of tooth whitening.

A combination of home and power whitening gives the advantage of faster whitening with the benefit of monitoring and motivating the patient throughout the treatment.

Conclusion

Tooth whitening is a non-invasive, economical, and highly effective aesthetic treatment for creating a bright smile. It should always be considered in aesthetic treatment planning to provide patients with a beautiful smile, giving them self-assurance and bringing them happiness.

Editorial note: This article was originally published in Cosmetic Dentistry Vol. 3, Issue 1, 2009.

Contact info

Dr So-Ran Kwon, Founder and President of the Korean Bleaching Society, lectures internationally on tooth whitening. She has written many articles and books on tooth whitening, including Tooth Whitening
in Esthetic Dentistry published by Quintessence. She is currently a visiting professor at Yonsei University and maintains a private practice in Seoul, Korea. Dr Kwon can be contacted at smileksr@hotmail.com.