Crack closure on rehydration of glass-ionomer materials.
Moisture-sensitivity of immature glass-ionomer cements suggests that hydration-induced volumetric expansion might close and potentially heal established cracks. Crack closure in glass-ionomer cements (GICs) was observed following rehydration. Circular cavities were prepared in 15 teeth: 10 were restored with resin-modified GICs (5 with Fuji II LC and 5 with Photac-Fil) and 5 were restored with a conventional GIC (Fuji IX); all were dehydrated for 1 min with air and imaged immediately by confocal microscopy. Crack formation in each was located, after which water was placed on the surface and observed for 15 min via a CCD camera. Dehydration caused cracks with measurable gaps, while rehydration resulted in varying degrees of closure: closure was limited in the conventional GIC, and complete or near complete along part/s of the crack in the resin-modified GICs. In all, closure movement became imperceptible after the first 10 min. Statistical analysis indicated no significant difference between the closure behavior of all materials. However, the resin-modified GICs appeared to show a greater potential for closure of established cracks than the conventional GIC upon rehydration.
Restorative Dentistry, School of Dental Sciences, University of Newcastle, Newcastle upon Tyne, United Kingdom.
Sharanbir K
SK
Sidhu
Peter
P
Pilecki
Martyn
M
Sherriff
Timothy F
TF
Watson
D000388:Air; D003737:Dental Cavity Preparation; D003743:Dental Enamel / Q000648:ultrastructure; D003775:Dental Polishing; D003890:Desiccation; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008422:Materials Testing; D018613:Microscopy, Confocal; D019279:Resin Cements / Q000737:chemistry; D012117:Resins, Synthetic / Q000737:chemistry; D013499:Surface Properties; D013997:Time Factors; D014867:Water / Q000737:chemistry
C079765:Fuji II LC cement; D005899:Glass Ionomer Cements; C081144:Photac-Fil; D019279:Resin Cements; D012117:Resins, Synthetic; C110713:fuji IX; D014867:Water