Limitations of this study include the relatively small sample size, which might prevent the authors to make conclusions regarding some factors such as patient preference among obturator height because of respective lack of enough data for more detailed statistical U0126 ERK evaluation. Further investigations with a large sample size that also evaluate other variables more than solely bulb height may permit a multivariate analysis. CONCLUSIONS A moderate buccal extension should be selected after gradually decreasing the bulb height for improved speech intelligibility in the most common type of surgical defects.
Dental fluorosis can influence esthetic perceptions, and its prevalence has increased over the past 50 years.
1 Excessive fluoride in drinking water, greater than 1 to 2 ppm, can cause metabolic alteration in the ameloblasts, resulting in a defective matrix and improper calcification of teeth.2 Dental fluorosis can also influence shear bond strength (SBS) of the orthodontic brackets. A significant decrease in SBS was reported when orthodontic brackets were bonded on fluorosed teeth.3 Effects of self etching primers (SEP) on SBS of orthodontic brackets are well documented.4�C6 Several authors reported that there was no difference between self etching and standard etching protocol on bond strengths.7�C12 On the other hand, lower bond strengths with SEP were also reported.13,14 To our knowledge, no study evaluated the efficiency of SEP when used for orthodontic bonding on fluorosed teeth. Therefore, the aim of this in vitro study was to evaluate the effects fluorosis and SEP on SBS of orthodontic brackets.
Our null hypothesis was that fluorosis and SEP do not affect SBS of orthodontic brackets. MATERIALS AND METHODS A total of 48 (24 fluorosed and 24 non-fluorosed) non-carious freshly extracted human permanent premolar teeth were used in this study. Fluorosed teeth were selected according to the modified Thylstrup and Fejerskov index (TFI), which is based on the clinical changes in fluorosed teeth. Each tooth was individually embedded in auto polymerizing acrylic resin (Meliodent, Herause Kulzer, Hanau, Germany). The specimens were kept in distilled water except during bonding and testing procedures. 48 fluorosed and non-fluorosed teeth were randomly assigned to 4 groups of 12 each. Before bonding, the facial surfaces of the teeth were cleaned with a mixture of water and pumice.
The teeth were rinsed thoroughly with water and dried with oil and moisture-free compressed air. Ormco Mini 2000 (Ormco Corp, Glendora, Calif) bicuspid metal brackets with 9.63 mm2 surface area were used. In groups I and II, each tooth was etched with 37% phosphoric acid gel for 30 seconds. Then, all teeth were rinsed with water/spray combination for 30 seconds and dried until characteristic frosty white etched area is observed. Light Bond (Reliance Orthodontic Drug_discovery Products, Inc., Ill, USA) was used as orthodontic adhesive.