Aim of the study. To compare the shear bond strength of metal brackets with foil mesh (3M, Victory Series), one piece metal brackets (Cannon Ultra) and aesthetic plastic brackets (Cannon Ultra) and to evaluate the sandblasting effect on previously used metal bracket bases regarding their bonding ability. Materials and Methods.A total of seventy human third molars were divided into four groups, and brackets were bonded to the enamel using Transbond XT. After 24 hours of storage, brackets were debonded with Instron Universal Testing Machine® and shear bond strength was recorded. Metal brackets were sandblasted until all visible bonding material was removed from the bracket base and then the bonding procedure and shear bond testing were repeated. Shapiro-Wilk test was used to check normal distribution. Student’s t-test was used to compare the shear bond strength. Results. The shear bond strength of one-piece metal brackets is significantly bigger (18.93MPa) than metal brackets with foil mesh (12.53MPa). Metal brackets in general demonstrate better bonding properties than aesthetic plastic brackets (8.61MPa). There is no statistically significant difference in shear bond strength between new and re-used sandblasted brackets. Conclusions. One-piece brackets with anchor pylons demonstrate better bonding properties but there is a higher risk of enamel damage during debonding of re-used sandblasted brackets.

The objective of this study was to compare the effects of the debonding of three different bracket types by means of three popular debonding methods. A total of 180 human third molars was divided into six groups, consisting of 20 teeth each. Three bracket types were bonded to the enamel (metal brackets with an integral base and a foil mesh base, and ceramic brackets) and three methods of bracket debonding were employed (bracket removal pliers, Weingart pliers, and Lift-Off Debonding Instrument). The samples were examined with scanning electron microscopy to assess the number of enamel cracks, measure the area of adhesive remaining on the enamel, and calculate the adhesive remnant index (ARI). There were no statistically significant differences between the groups in terms of the number of enamel cracks after bracket debonding. The amount of adhesive remaining on the teeth after the brackets were removed was significantly different between the groups. LODI and Weingart pliers are considered to be the safest methods of debonding brackets with an integral base, while LODI is the best tool for brackets with foil mesh. Bracket removal pliers are considered to be the preferred method for ceramic bracket debonding.

Introduction: Premature loss of deciduous teeth is considered to be one of the local environmental factors interfering with normal development of the occlusion. Extraction of deciduous tooth before the time of its physio logical exfoliation carries the risk of creation of unfavorable spatial changes in sagittal, transverse and vertical plane. Despite the undeniable role of wellpreserved primary dentition in the development of occlusion in adult hood, there are still controversies regarding indications for implementation of space maintainers. Objectives: Analysis of available literature in terms of consequences of premature loss of deciduous molar teeth. Material and methods: The literature review was conducted in PubMed, EMBASE and Scopus databases in July 2017 basing on keyword "premature primary tooth loss". English and Polishlanguage magazines were taken into account without specifying the time frame. Results: In total, 20 papers were selected for further detailed analysis, of which 11 were based on longitudinal studies, 9 were crosssectional studies (including 7 retrospective studies and 2 systematic literature reviews). Conclusions: Premature extraction of the upper first primary molar may lead to buccal eruption of permanent canine as a consequence of more mesial eruption of first premolar. Increased risk of space loss within dental arch exists especially in case of coexistence of cusp to cusp relationship on first molars and leptoprosopic facial type. Consequences of losing lower first deciduous molar are less obvious. Extraction of second deciduous molars may result in much more serious disturbances related to mesial migration of first permanent molars, resulting in re tention or abnormal eruption of second premolars. Repercussions of early loss of deciduous teeth are often visible only at the moment of eruption of permanent successors and depend on many variables, among which patient's age at the time of extraction, initial spatial conditions (crowding/spacing) and the number and type of lost teeth should be mentioned.

Introduction. Loss of space in the maxillary arch is a frequent consequence of early loss of deciduous molars indicating distalisation of the mesialised molar tooth. A number of methods using either extra-oral appliances or intra oral appliances of various types have been suggested. While extra-oral appliances exert a high but intermittent force many of the intraoral ones deliver a modest, though constant, force and demands no patient cooperation. Aim of study. To investigate the effect of an intra-oral fixed appliance (Distal Driver) based on a NiTi spring incorporating also a standardised anchorage unit on the position of the maxillary first molar as well as on the facial skeleton and the dentition in general. Material and methods. The experimental group comprised 6 child patients exhibiting a distal molar relationship (Unilateral or Bilateral) of at least ½ premolar unit. The mesialised molars were distalised by means of a “Distal driver” exerting a force of 150 gm for a period of 3-4 weeks. Anchorage was created by a fixed modified palatal bar cemented on the premolars supporting an acrylic palatal button ad modum Nance. The clinical situation was recorded before and after molar distalisation by means of study casts, cephalograms, panoramic radiographs as well as intra-oral photographs. The distalisation of the molars as well as the effect on anchorage teeth was quantitated on digital models derived from the plaster casts. Evaluation of the observed distal and vertical changes in molar position was performed on the lateral cephalogram. Results. Cast analysis showed a clear distalising effect on the maxillary first molars ranging from 1.25 mm to 6.18 mm as well as mesial movement of the premolar anchorage teeth from 0.46 mm to 5.55mm. The cephalometric analysis revealed a first molar distalisation of 0.9 mm to 5.6 mm though again with a mesial movement of the first premolar varying from 0.5 mm to 3.7 mm. A clear distal tipping of the first and second molars simultaneously with a mesial tipping of the first premolars was also recorded. Conclusion. The Distal Driver constitutes an efficient method of maxillary molar distalisation though is often accompanied by a distal rotation of these teeth and a mesial tipping of the anchorage premolars. Careful monitoring of anchorage loss is necessary if good results are to be achieved.

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