Dental floss ties for rubber dam isolation: A proposed classification and a new technique.

Rubber dam application has become an essential part of restorative dentistry. In late 2019, dentistry faced a new challenge with the COVID-19 pandemic and therefore, the implementation of extra isolation methods became crucial. This article introduces a classification of dental floss ties used with a rubber dam, including the "simple" ties that are subdivided into traditional ties, single-loop self-ligating ties and double-loop self-ligating ties, and a new state-of-the-art design. The "compound tie" design incorporates a combination of one or more subdivisions of the simple ties. This new design may provide better isolation and more consistent gingival tissue retraction. Furthermore, due to the advanced technique applied, the tie will offer improved stability and prevent the sheet from sliding over the dental floss tie from all surfaces.

An intraoral method of verifying interocclusal distance for completely edentulous patients.

This article describes a method of verifying the interocclusal distance of edentulous patients by using acrylic resin wafers of different thicknesses. The wafers are attached to the occlusal surface of the maxillary wax occlusal rim in the first premolar region to facilitate intraoral verification of the proposed interocclusal distance. This method is straightforward and reduces the registration of an incorrect interocclusal distance.

Nucleation efficacy and flexural strength of novel leucite glass-ceramics.

OBJECTIVES: To optimize the nucleation mechanism in leucite glass-ceramics to allow more efficacious glass-ceramic manufacture and improvements in microstructure and mechanical reliability. MATERIALS AND METHODS: An alumino-silicate glass was designed and synthesized using melt quench methods. The glass was crushed and milled using various milling times (48-93h) and spray drying. Nucleation and growth heat treatment schedules were applied to synthesize glass-ceramics. Glass/glass-ceramic powders and frit specimens were characterized using differential scanning calorimetry (DSC), transmission electron microscopy (TEM), energy-dispersive X-ray spectrometry (EDX), magic angle spinning nuclear magnetic resonance spectroscopy (MAS-NMR) and X-ray diffraction analyses (XRD). Glass-ceramic specimens were tested using the biaxial flexural strength test (BFS). RESULTS: Application of defined nucleation heat treatments resulted in the synthesis of Na/Ca titanates. NMR indicated changes to the 23Na glass spectra in the nucleated glass and TEM/EDX the presence of Na/Ca/Ti domains (<200nm) within the leucite crystals and associated with the nucleation of the leucite phase. XRD confirmed the presence of a bulk leucite phase in the glass-ceramics. SEM/TEM confirmed the crystallization of the leucite phase (65.5-69.3%) in a thermally matched glass, in conjunction with the nano Na/Ca titanate phase. The leucite glass-ceramics resulted in a high BFS (255-268MPa), with reduction in powder milling time prior to heat treatments having no significant effect on flexural strength and reliability (p>0.05). SIGNIFICANCE: Na/Ca titanates were synthesized in leucite glass-ceramics for the first time and associated with its nucleation and efficacious growth. This nucleation optimization provides opportunities for more efficient manufacturing and microstructural/mechanical reliability improvements. Improved synthesis of high strength/reliable leucite glass-ceramics is useful for construction of esthetic minimally invasive restorations.

Effect of sandblasting, etching and resin bonding on the flexural strength/bonding of novel glass-ceramics.

OBJECTIVES: To process novel leucite glass-ceramics and test the effects of surface treatment and resin bonding on the biaxial flexural strength (BFS) and shear bond strength (SBS). METHODS: Alumino-silicate glasses were ball-milled, and heat treated to form leucite glass-ceramics (LG-C, OLG-C), then sintered into ingots. Ingots were heat extruded into a refractory mould to form disc specimens (1.3×14mm diameter). IPS e.max® was used as a commercial comparison. Glass-ceramic test groups were sandblasted (Groups. 1, 4, 6), sandblasted, etched and adhesively bonded (Groups. 2, 5, 7) or lapped, etched and adhesively bonded (Groups. 3, 8). Specimens were adhesively bonded with Monobond S, followed by the application of Variolink II® cement and light curing. BFS testing was at 1mm/min and SBS testing at 0.5mm/min. Samples were characterised using XRD, SEM and profilometry. RESULTS: XRD confirmed tetragonal leucite in LG-C/OLG-C and lithium disilicate/lithium orthophosphate in IPS e.max®. Mean BFS (MPa (SD)) were: Gp1 LG-C; 193.1 (13.9), Gp2 LG-C; 217.7 (23.0), Gp3 LG-C; 273.6 (26.7), Gp4 OLG-C; 255.9 (31); Gp5 OLG-C; 288.6 (37.4), Gp6 IPS e.max®; 258.6 (20.7), Gp7 IPS e.max®; 322.3 (23.4) and Gp8 IPS e.max®; 416.4 (52.6). The Median SBS (MPa) were Gp1 LG-C; 14.2, Gp2 LG-C (10s etch); 10.6 and Gp3 IPS e.max®; 10.8. Mean surface roughness was 5-5.1µm (IPS e.max®) and 2.6µm (LG-C). SIGNIFICANCE: Novel leucite glass-ceramics with reduced flaw size and fine microstructures produced enhanced BFS and SBS by resin bonding. These properties may be useful for the fabrication of minimally invasive aesthetic and fracture resistant restorations.

Replacement of missing lateral incisors with lithium disilicate glass-ceramic veneer-fixed dental prostheses: a clinical report.

KEY CLINICAL MESSAGE: This report describes the use of lithium disilicate glass-ceramic veneer-fixed dental prostheses in replacing congenitally missing maxillary lateral incisors. This kind of prosthesis has an advantage over a lingual-retainer resin-bonded fixed dental prosthesis in its capability of changing the color and shape of the abutment teeth. The prostheses provided an acceptable esthetics and comfort for the patient.