ABSTRACT
Smear layers are very soluble in acidic solutions. Removal of smear layers increases dentin permeability and the potential for pulpal irritation. In this study, smear layers were treated with either saline, Barrier, Copalite, LC-Scotchbond, Hydroxyline, or DDS 1 & 2 to determine how well they protected the dentin from subsequent acid attack with 37% phosphoric acid for two minutes. Using both SEM and permeability measurements, the materials were ranked from least to most effective as: Saline less than Barrier = Copalite less than Hydroxyline = Scotchbond = DDS 1 & 2.
Subject(s)
Dental Cavity Lining , Dentin Permeability/drug effects , Tooth Permeability/drug effects , Acid Etching, Dental , Dental Leakage , HumansABSTRACT
Resin casts were made of microleakage channels surrounding amalgam restorations in vitro. After demineralizing the tooth and digesting the remaining organic matrix, the amalgam restorations covered with the resin casts were examined using a scanning electron microscope. An extensive reticular network of channels was observed on restorations which were placed in cavities lined by smear layers. Amalgam restorations placed in cavities devoid of smear layers exhibited fewer microleakage channels.
Subject(s)
Dental Leakage/etiology , Dental Amalgam , Dental Restoration, Permanent , Microscopy, Electron, ScanningABSTRACT
The effects of a constant blast from the Prophy-Jet directed at enamel, dentin, and cementum over 5-, 10-, 15-, 20-, 30-, 40-, 50- and 60-second periods were evaluated to determine what effects the spray had on tooth structure. There was no visible effect on enamel when the spray was directed at the surface for as long as 60 seconds. It was shown, however, that as little as 5 seconds of continuous spray caused a substantial loss of structure when the spray was directed at dentin and cementum. This structural loss was linearly related to the amount of time the area was subjected to the spray. Substitution of flour of pumice for the Prophy-Jet powder resulted in approximately the same rate of loss of root structure. The results suggest that the manufacturers should provide more explicit warnings regarding the abrasiveness of the device on exposed dentin and cementum areas.
Subject(s)
Dental Prophylaxis/instrumentation , Tooth Abrasion/pathology , Tooth Root/anatomy & histology , Dental Cementum/anatomy & histology , Dental Enamel/anatomy & histology , Dental Prophylaxis/adverse effects , Dentin/anatomy & histology , Humans , Time Factors , Tooth Abrasion/etiologyABSTRACT
The layer was evaluated by scanning electron microscopy and by measurement of hydraulic conductance before and after 2-min topical treatment with potassium chloride, neutral potassium oxalate, half-neutralized oxalic acid or both neutral and acidic oxalates. The treated smear layers were then re-evaluated microscopically and functionally both before and after acid challenge. The layers treated with KCl were not altered either microscopically or functionally and were susceptible to acid etching. Dentine surfaces treated with either oxalate solutions became less permeable and were acid-resistant.
Subject(s)
Dentin Permeability/drug effects , Dentin/drug effects , Oxalates/pharmacology , Tooth Permeability/drug effects , Dentin/ultrastructure , Humans , Hydrogen-Ion Concentration , In Vitro Techniques , Microscopy, Electron, Scanning , Oxalic AcidABSTRACT
Patients using placebo dentifrices in clinical trials usually show a significant decrease in dentin sensitivity over a 2- to 4-week period. If their sensitivity were due to hydrodynamic fluid movement, then the results suggest that there was a decrease in their dentin permeability. This hypothesis was tested in vitro by measuring the ease with which fluid could flow (i.e., hydraulic conductance) across dentin discs before and after brushing the discs with a variety of dentifrices, including most of the marketed densensitizing dentifrices. All dentifrices decreased the hydraulic conductance of dentin. An experimental dentifrice containing oxalate as the active ingredient was far more effective than any of the marketed dentifrices. The results tend to support the hypothesis that, at least part of the reduction in clinical sensitivity in patients with hypersensitive dentin is due to the abrasive action of the dentifrice.
Subject(s)
Dentifrices/pharmacology , Dentin Permeability/drug effects , Dentin Sensitivity/physiopathology , Tooth Permeability/drug effects , Dentin Sensitivity/metabolism , Humans , Oxalates/pharmacology , Pressure , Toothbrushing , WaterABSTRACT
The effects of evaporation produced by air blasts of 0, 0.5, 2 or 5 min to dentine in vitro were evaluated by measuring dentine hydraulic conductance before and after each trial. When the tubules were filled with water, even prolonged evaporation had no effect on dentine permeability. Tubules filled with physiological salt solution produced a time-dependent decrease in dentine permeability. Tubules filled with 1.5 per cent albumin in water gave the largest reductions in dentine permeability. These effects were more marked in unetched as opposed to acid-etched dentine. The results suggest that part of the reduction in dentine sensitivity produced clinically by prolonged air blasts may be due to precipitation of organic and inorganic constituents of dentinal fluid at the surface.
Subject(s)
Air , Dentin Permeability , Tooth Permeability , Acid Etching, Dental , Albumins/metabolism , Humans , In Vitro Techniques , Sodium Chloride/metabolism , Water/metabolismABSTRACT
Dentine permeability measurements were made each hour for 6 h in tooth cavities prepared in control dogs or dogs which had been pretreated with a purified fraction of snake venom to deplete their plasma of fibrinogen. The control dogs exhibited a progressive fall in dentine permeability (approximately 50 per cent reduction in 6 h); the permeability in the fibrinogen-depleted dogs only fell 15 per cent in 6 h. The results implicate plasma proteins, particularly high molecular-weight proteins such as fibrinogen, as agents which reduce dentine permeability in vivo.
