Proximal contact tightness between direct-composite additions in the posterior dentition: an in vitro investigation.
OBJECTIVE
The aim of the study was to test whether a novel three-step matrix technique for posterior direct-composite additions creates sufficiently strong proximal contacts.


METHODS
Contact tightness was measured between direct-composite additions and between original teeth on a model. Therefore, the frictional forces required to remove a straight, 0.05-mm-thick, metal matrix band inserted between adjacent teeth and held by a universal testing machine (Zwicki, Zwick GmbH, Ulm, Germany) were recorded. Measurements were taken at three time points to carry out reference analysis: at baseline, after removal of the maxillary right second premolar (tooth #15) to simulate a diastema, and after closure of the diastema by inserting two direct-composite additions with the three-step matrix technique on the maxillary right first premolar (tooth #14) and first molar (tooth #16). Measurements were performed in the maxillary right (first) and left (second) quadrants to document sagittal displacement.


RESULTS
The original contact tightness values were between 1.65 ± 0.88 N and 3.05 ± 0.60 N in the first quadrant and between 1.23 ± 0.51 N and 2.18 ± 0.43 N in the second quadrant. After removal of tooth 15, values decreased significantly in the first quadrant and insignificantly in the second. After reconstruction, the contact tightness between teeth 14 and 16 was significantly stronger (tighter) (3.20 ± 0.80 N) than the originally measured contact tightness between teeth 14 and 15 (2.86 ± 0.64 N) and teeth 15 and 16 (1.65 ± 0.88 N) (p=0.006 and 0.001, respectively).


CONCLUSIONS
Within the limitations of an in vitro investigation, this study has shown that by using a novel, three-step matrix technique, direct posterior composite additions can form sufficiently tight proximal contacts.
University of Heidelberg, Department of Conservative Dentistry, Heidelberg, Germany. diana.wolff@med.uni-heidelberg.de
Diana
D
Wolff
Philipp
P
Hahn
Paul
P
Ding
Theresa
T
Maier-Kraus
Cornelia
C
Frese
Christof
C
Doerfer
Hans Joerg
HJ
Staehle
D003188:Composite Resins; D003793:Dental Restoration, Permanent / Q000379:methods*; D003970:Diastema / Q000628:therapy*; D006801:Humans; D008434:Matrix Bands; D003765:Models, Dental; D010865:Pilot Projects
D003188:Composite Resins