[The impact of ultrasonic dental hygiene procedures on the bonding strength of restorations].

Ultrasonic calculus scaling has become a common oral hygiene procedure in patients with composite restorations, dental veneers, orthodontic brackets. The aim of the study was to evaluate in vitro the influence of the EMS-ultrasonic system scaling on the flowable composite bond strength to the tooth enamel, dentine, and e-max ceramic. The samples were divided into three groups: 1 group (composite bonded to enamel), 2 group (composite bonded to dentine), 3 group (composite bonded to e-max ceramic). The bonded samples were loaded to failure in the universal testing machine. The shear bond strength was calculated in newtons (N). T (Student's)-test was used to evaluate the data. Significantly lower bond strengths were observed with the ultrasonic treated samples in each groups. The EMS-ultrasonic system scaling significantly decreases the flowable composite bond strength to the tooth enamel, dentine, and e-max ceramic.

[The dynamics of blood circulation in marginal gingiva after crown preparation by different ledge locations].

The periodontal tissue level may change after gingival margin retraction and tooth preparation. The aim of the study was to assess the influence of these manipulations on the condition of free gingival margin. The study included 53 persons (29 women and 24 men) divided into 4 groups followed-up for 6 to 8 weeks. Blood circulation in marginal gingiva of 118 teeth with healthy periodontal tissues was assessed by ultrasonic Doppler evaluation to reveal the circulation impairments in cervical margin after teeth crown preparation. The first group included 39 teeth, in which the gum was retracted by Roeko stay put non impregna cords ("Langenau", Germany). The second group included 39 teeth with shoulders prepared at the gingival margin; in the third group (40 teeth) the shoulder was located subgingivally. The fourth group (40 teeth) was control. The changes in recovery indices have been analyzed. The linear values were established as most significant and demonstrative. The indices variations and recovery period length depended on the coronal edge location. Statistically significant differences were found among all the groups (p>0.05). The results may be used to improve crown preparation for fixed dentures and decrease the recession rate of free gingival margin.