Calcium Hydroxide Treatment Research Articles

The effect of calcium hydroxide and urea treatment of barley straw on chemical composition and digestibility in vitro

An experiment was conducted to investigate the effectiveness of calcium hydroxide (Ca(OH) 2) and urea treatment of straw. Chopped barley straw was treated with mixtures of Ca(OH) 2 (0, 30 and 60 g kg −1 straw dry matter, DM) and urea (0, 30 and 60 g kg −1 straw DM) dissolved in 0.81 water kg −1 straw DM and ‘ensiled’ in a polythene bag (1.0 kg per bag) at 15°C or 25°C for 60 days. Control treatment at each temperature involved untreated straw and treatment with 30 or 60 g NaOH kg −1 straw DM dissolved in 0.81 water kg −1 straw DM. Ensiled straws were examined for mould, chemically analysed and assessed for organic matter digestibility (OMD) in vitro. Mould occurred in Ca(OH) 2-alone and water-alone ensiled straw, but other ensiled straws were apparently mould free. In the presence of Ca(OH) 2 with urea treatment, the nitrogen content of ensiled straw increased more than urea-alone treatment. Analysis of variance of OMD in vitro results showed that Ca(OH) 2, urea and temperature interact significantly ( P < 0.01). Interactions were found to be non-significant for other parameters (nitrogen, acid detergent fibre and hemicellulose). However, straw ensiled at 15°C with 30 g urea +60 g Ca(OH) 2 kg −1 straw DM, 60 g urea +60 g Ca(OH) 2 kg −1 straw DM or 30 g NaOH kg −1 straw DM had similar OMD in vitro (67%). Untreated straw OMD was 48.5%. It can be concluded that mixtures of Ca(OH) 2 and urea would be the alternative chemicals to NaOH or ammonia for improvement of the nutritive value of straw.

Alteration of biological properties of bacterial lipopolysaccharide by calcium hydroxide treatment

Bacterial lipopolysaccharide (LPS) plays a major role in the development of periapical bone resorption. Although the chemical properties of LPS are altered by treatment with an alkali such as calcium hydroxide, the effects of calcium hydroxide on the biological properties of LPS are not known. The purpose of this study was to investigate whether treatment of LPS with calcium hydroxide alters its biological action as measured by human monocyte secretion of prostaglandin E2. Monocyte cell cultures were stimulated with LPS or calcium hydroxide-treated LPS and culture supernatants were analyzed for prostaglandin E2 content using gas chromatography-mass spectrometry. Prostaglandin E2 was identified in supernatants of LPS-stimulated monocytes but not in those stimulated with calcium hydroxide-treated LPS. It was concluded that the treatment with calcium hydroxide may alter biological properties of bacterial LPS.

Ammonia and/or calcium hydroxide treatment of maize stover: intake, digestibility and digestion kinetics

Six ruminally fistulated steers were used in a 6 × 6 Latin square design to measure effects of treatments on maize stover. Maize stover was ground through a 0.95-cm screen and water was added to reduce the dry matter (DM) to 65% before chemical treatment. The chemical treatments were: 30 g NH 3, 56 g urea, 40 g Ca(OH) 2, 30 g NH 3 + 40 g Ca(OH)2 or 56 g urea + 40 g Ca(OH) 2 per kg maize stover DM. Untreated maize stover (65% DM) was used as the control. All chemical treatments were allowed to react for at least 14 days at 21°C. Chemical treatment increased ( P < 0.05) the intake of organic matter (OMI) and digestible organic matter intake (DOMI), organic matter digestibility (OMD), fiber digestibility and rate of particulate passage. However, Ca(OH) 2 treatment of maize stover did not improve intake and digestibility. Treating maize stover with Ca(OH) 2, plus either NH 3 or urea increased ( P < 0.05) intake, digestibility and rate of particulate passage over Ca(OH) 2 treatment alone. Chemical treatment had no significant effect on the rate of fluid passage, flow rate or ruminal fluid volume. When steers were fed equal portions, chemically treated and untreated maize stover had slower, but similar rates of particulate passage and generally higher digestibilities compared with ad libitum intake. Chemical treatment increased ( P < 0.05) the extent of the cell wall digestion, but rates of fiber digestion were not affected. Among chemical treatments, NH 3 and urea consistently improved the feeding value of maize stover. The results of the study indicate that the addition of Ca(OH) 2 to either NH 3 or urea is no better than using NH 3 or urea alone.

Effect of calcium hydroxide on bacterial lipopolysaccharide

Apical periodontitis and its concomitant periapical osteolysis is caused by pulpal infection, and bacterial lipopolysaccharide (LPS) is known to play a major role in the bone resorption process. Little is known concerning the effect of root canal intervisit dressings on residual LPS in root canals after bacterial cell lysis. The purpose of this study was to evaluate the effects of calcium hydroxide on bacterial LPS. Free hydroxy fatty acids were quantified in samples of LPS treated with calcium hydroxide. Calcium hydroxide treatment of LPS was shown to release elevated quantities of hydroxy fatty acids. It was concluded that calcium hydroxide hydrolyzed the lipid moiety of bacterial LPS, resulting in the release of free hydroxy fatty acids. This result suggests that calcium hydroxide-mediated degradation of LPS may be an important reason for the beneficial effects obtained with calcium hydroxide use in clinical endodontics.

Evaluation of economical sorbents for removal of metolachlor from rinsate wastewater

Small-scale farm operators and applicators are in urgent need of inexpensive user-friendly methods to decontaminate dilute formulated pesticide solutions such as rinsate solutions. One requisite to development of such methods is the identification and selection of inexpensive effective sorbents. Three different sorbents (rubber, sphagnum peat moss, and steam-exploded wood [SEW]) were evaluated for their ability to remove analytical grade and formulated metolachlor (as Dual 8E, an emulsifiable concentrate) from an aqueous phase, using the batch equilibrium method. Rubber proved to have the greatest sorptive capability, followed by peat and SEW. At the highest concentration of (formulated) pesticide tested (400 mg L −1), rubber was 85% efficient in removing metolachlor from solution, while peat and SEW were 71% and 55% efficient in metolachlor removal. The presence of surfactants in the formulated pesticide appeared to decrease metolachlor sorption. The addition of Ca(OH) 2, a demulsifying agent, to the formulated pesticide suspensions (400 mg L −1) decreased the sorption capability of peat and SEW by 31% and 20%, respectively. Calcium hydroxide treatment increased sorption capability of rubber by 3%. The combination of Ca(OH) 2 and rubber proved to be the superior treatment in terms of removing formulated metolachlor from solution.

Calcium hydroxide treatment of malt distillers' grains 2. Effects on apparent digestibilityin vivo, intake and performance in sheep

AbstractThe effects of calcium hydroxide (Ca(OH)2)treatment of malt distillers' grains (MDG) on apparent digestibilityin vivo, food intake and lamb performance were measured in three experiments. Experiment 1 measured effects on intake and apparent digestibility of wet MDG either untreated (C), mineralized with a high-calcium mineral (M), Ca(OH)2treated at ambient temperature (L) or at 70°C for 72 h (LH) and offeredad libitumto mature wether sheep (approx. 75 kg live weight). Dry matter (DM) intakes for MDG were 1251,1585,1838 and 1889 (s.e. 93) g/day for C, M, L and LH respectively when given with 780 g DM per day of a standard complete diet (diet A). Corresponding values for whole diet organic matter (OM) apparent digestibility when MDG was given at a fixed rate (1250 g DM per day) with a standard diet (660 g DM per day diet A) were 049, 049, 0·58 and 0·60 (s.e. 0·008) respectively. Experiment 2 compared mineralized wet MDG (M) with a prototype dried food made from Ca(OH)2-treatedensiled MDG (neutralized with NaOH before treatment) held at 60°C for 18 h before drying (NID) and a proprietary lamb finishing compound (PC). The supplements were offered at an increasing rate (350 g DM per day to 1200 g DM per day) to 30 Blackface lambs of approximately 31 kg initial live weight, penned in pairs, and givenad libitumaccess to hay and water. Mean DM intakes (g DM per day) to day 60 for supplements were 925, 750 and 934 (s.e. 19) and for hay were 258, 200 and 311 (s.e. 17) for NID, M and PC respectively. Corresponding values for live-weight gain (g/day) were 136, 123 and 130 (s.e. 11); for condition score (day 59) were 3·9, 3·6 and 4·0 (s.e. 0·06) and for number of lambs finished at day 60 were 8, 2 and 10. Experiment 3 evaluated the apparent digestibility and effects on rumen function of NID, M and PC fed at a fixed rate with chopped hay (804 g DM per day supplement + 396 g DM per day hay) to rumen fistulated wethers (approx. live weight 70 kg). Apparent digestibility values for OM were 0·63, 0·53 and 0·65 (s.e. 0·015) and for neutral-detergent fibre were 0·69, 0·55 and 0·57 (s.e. 0·037) for NID, M and PC respectively. Rumen pH, volatile fatty acid concentrations or hay digestibility in sacco were not significantly affected by supplement. Ca(OH)2treatment greatly improved the nutritional characteristics of MDG giving substantial improvements in apparent digestibility, intake and performance.

Effect of different endodontic treatment protocols on periodontal repair and root resorption of replanted dog teeth

This study examined, histologically, the healing of intentionally damaged root surfaces of replanted teeth with either uninfected or infected root canals treated with short- and long-term calcium hydroxide. Thirty beagle dog incisors were randomly divided into four groups. In group 1, uninfected obturated incisors were extracted, the roots were longitudinally grooved and the teeth were replanted within 2 min. In group 2 the root canals were artificially infected followed by extraction, longitudinal grooving, and replantation as described in group 1. Fourteen days after replantation, the root canals were fully instrumented and medicated with intracanal calcium hydroxide. One week later the root canals were permanently obturated with gutta-percha and sealer. The teeth in group 3 were treated as described in group 2 but after 1 wk the calcium hydroxide dressing was repacked for the duration of the study. In group 4 (positive control) the teeth were treated as described in groups 2 and 3 but no endodontic treatment was performed. After 8 wk, sacrifice and histological preparation were carried out. In group 1 complete cemental repair was seen in all teeth. In groups 2 and 3, complete and incomplete cemental repair was seen in seven and two teeth, respectively. An ankylotic area was present in one tooth in group 3. None of the teeth in group 4 showed cemental repair. It was concluded that short- and long-term calcium hydroxide treatment resulted in similar healing patterns when endodontic treatment is initiated 14 days after replantation of teeth.

Calcium hydroxide treatment of malt distillers' grains 1. Effects on chemical composition and digestibility measuredin vitroandin sacco

AbstractExperiment 1 investigated the effects of calcium hydroxide (Ca(OH)2)treatment (80 g/kg malt distillers' grains (MDG) dry matter (DM) at ambient temperature (L) and at 60°C (LH). Organic matter digestibilitiesin vitro(1V0MD) were 0·30, 0·50 and 0·56 (s.e. 0·023) for untreated (C), L and LH respectively. The increase in IVOMD was less with MDG that had previously been ether-extracted (corresponding values 0·47, 0·53 and 0·54). The proportion of lipid in soap form was 0·03, 0·35 and 0·46 (s.e. 0·03) for C, L and LH respectively. Experiment 2 investigated the effects of treatment time, temperature and Ca(OH)2concentration on composition, IVOMD and organic matter digestibility in sacco (ISOMD). Response was most dependent on Ca(OH)2concentration. Mean values for 0, 40, 80 and 120 g Ca(OH)2per kg DM were for neutral-detergent fibre (NDF) (g/kg DM) 704, 586, 422 and 382; for water-soluble carbohydrate (g/kg DM) 2, 4,40 and 44; for ISOMD 0 h (without incubation) 0·25, 0·25, 0·51 and 0·57; for ISOMD 24 h (24-h rumen incubation) 0·63, 0·66, 0·84 and 0·86 and for IVOMD 0·51, 0·55, 0·65 and 0·65. Increasing treatment temperature from 20 to 80°C increased mean ISOMD 0 h from 0·31 to 0·49 but had less effect on ISOMD 24 h (0·74 and 0·79 respectively). Experiment 3 investigated the effects of treatment with 80 g Ca(OH)2per kg DM at 60°C for 16 h on rumen degradation in sacco. Instantaneous losses (a values%) for OM and NDF were increased by treatment from 14·6 to 45·5 and from 8·6 to 18·6 respectively. Treatment increased effective degradability (at 0·06 per h rumen outflow rate) from 0·43 to 0·66 for OM and from 0·40 to 0·46 for NDF. Total potentially digestible OM (a + b) increased from 0·65 to 0·91 for OM and from 0·58 to 0·84 for NDF. Ca(OH)2treatment enhances the nutritional value of MDG. Its mode of action involves reduction of the toxicity to rumen micro-organisms of unsaturated lipid by soap formation and the effect of alkali on the composition of the carbohydrate fraction.

Prognosis of luxated non-vital maxillary incisors treated with calcium hydroxide and filled with gutta-percha. A retrospective clinical study.

A material of 885 luxated, non-vital incisors was evaluated radiographically with respect to healing of periodontal tissues including inflammatory root resorption and occurrence of ankylosis and cervical root fractures. The results were assessed after completion of calcium hydroxide treatment and 4 years after filling of the root canal with gutta-percha. After treatment with calcium hydroxide, periapical healing occurred in 95% of the teeth. Four years after filling with gutta-percha, periapical healing was present in 91% of the teeth. In the remaining teeth, recurrent or persistent periapical radiolucency was more frequent in overfilled than adequately filled teeth (P = 0.0001). There was no difference between immature and mature teeth. Inflammatory root resorption healed in 192 of 197 teeth (97%); in 5 teeth it developed into ankylosis. Ankylosis occurred in 13 teeth, all of which were intruded into the alveolar bone at the time of injury. The frequency of cervical root fractures was markedly higher in immature than mature teeth (P greater than 0.0001). Among immature teeth, the frequency of fractures was dependent on the stage of root development (chi 2 = 31.6) and ranged from 77% in teeth with the least to 28% in teeth with the most developed roots. The frequency of fractures was also related to the defects after healing of inflammatory root resorption in the cervical area of the root, significant at P less than 0.0001.

Effect of delayed calcium hydroxide treatment on periodontal healing in contaminated replanted teeth

The effect of delayed intracanal calcium hydroxide treatment on experimentally induced extensive inflammatory root resorption in monkeys was studied. A significant shift from inflammatory resorption to ankylosis was noted following calcium hydroxide treatment. Furthermore, calcium hydroxide treatment appeared to change the pattern of ankylosis over time, although the total ankylotic area remained the same. Ankylosis preceded by root resorption (replacement resorption) increased, while ankylosis not associated with root resorption decreased. It was concluded that intracanal calcium hydroxide treatment of teeth with compromised PDM may cause unnecessary replacement resorption if left in the root canal for a long time or changed repeatedly.

Effect of immediate calcium hydroxide treatment and permanent root‐filling on periodontal healing in contaminated replanted teeth

The effect of immediate permanent root-filling and immediate intracanal calcium hydroxide treatment on experimentally contaminated and necrotized periodontal membranes (PDM) in avulsed and subsequently replanted monkey teeth was studied. Almost the entire root surface in the non-endodontically treated control teeth were covered with inflammatory resorption. A significant shift towards ankylosis not associated with root resorption (greater than 80% of the total root surface area) was noted following calcium hydroxide treatment. About two thirds of the root surfaces from the teeth with permanent root fillings showed surface resorptions or ankylosis preceded by root resorption. The root surface area which would have been covered by inflammatory resorption, unless endodontic treatment had been implemented, were instead predominantly covered by either surface resorption (permanent root filling) or ankylosis (calcium hydroxide treatment). Ankylosis compared with surface resorption may in the long term lead to progressive loss of root substance due to replacement resorption. It was concluded that calcium hydroxide may be an excellent initial intracanal treatment in teeth with healthy PDM, but care should be taken not to risk unnecessary development of ankylosis by prolonged treatment of teeth with compromised PDM.

Calcium Hydroxide In Treatment Of Traumatized Teeth

Calcium hydroxide is used in the treatment of different traumatized teeth. New concepts about the effects of calcium hydroxide on vital pulps and immature non vital teeth are developed. Some clinical techniques and their results are described.

The effect of calcium hydroxide treatment of spent grains on their digestion and utilisation by finishing lambs

The use of malt distillers grains (draff) in ruminant diets is limited both by its moderate digestibility and variable intake. This is due to the low digestibility of its fibre and to the inhibitory effects of its unsaturated oil on rumen cellulolysis. Treatment of draff with Ca(OH)2 may ameliorate these limitations in two ways. Firstly, alkali treatment increases fibre digestibility due to hydrolysis of lignocellulosic linkages. Secondly, under alkaline conditions and in the presence of calcium ions, the unsaturated fatty acids of the draff oil form insoluble calcium soaps, thus reducing their inhibitory effects on rumen function.Thirty Blackface-cross lambs were allocated by sex and weight to three groups of ten. The animals were penned in pairs and were offered hay ad libitum and supplemented with 350g DM/d of either mineralised draff (MD), limed draff (LD - draff treated with 80g Ca(OH)2 /kg DM, held at 60°C for 18 hours and then dried at 60°C), or a proprietary lamb finishing concentrate (C - Premium Sheep Fattening Pellets, Carrs Farm Foods, Solway Mills, Silloth). The supplements were gradually increased to 1200g DM/d over 60 days. Dry matter intakes of hay and supplements were measured daily and animals were weighed weekly. The lambs were condition scored ‘blind’ on day 60 and were assessed for slaughter.

Evaluation of Calcium Carbonate and Calcium Hydroxide Treatments of Prairie Drinking Water Dugouts

ABSTRACT In 1987, lime (250 mg/L calcium carbonate or 250 mg/L calcium hydroxide) was added to four hardwater dugouts in northwestern Alberta to precipitate the phosphorus and algae and improve water quality. Calcium carbonate reduced algal biomass to 39 percent of pretreatment concentrations between June and August of 1987, but dugouts recovered to pretreatment concentrations during the next summer. Calcium hydroxide treatments reduced algal biomass to 12 percent of pretreatment concentrations and dugouts remained at that level over the following summer. Phosphorus concentrations were decreased by 80 percent in calcium hydroxide-treated dugouts but were relatively constant in calcium carbonate-treated dugouts. Calcium hydroxide treatments can improve water quality in dugouts for a chemical cost of $200–$400.

Effect of calcium hydroxide or urea treatment of barley straw on intake and digestibility in sheep

Three experiments were undertaken with 7 to 8-month-old Suffolk cross Mule lambs weighing 35 kg (Experiment 1) and 29 kg (Experiments 2 and 3). Rations of restricted concentrates (176 g dry matter (DM)/day, Experiment 1; 142 g DM/day, Experiments 2 and 3), and ad libitum straw (Experiments 1 and 2) or restricted straw (Experiment 3) were fed over 35 days per experiment to measure intake (10 days) (Experiments 1 and 2) and digestibility (8 days faeces collection). Chopped straw was mixed with Ca(OH) 2 and/or urea dissolved in 0.8 1 water/kg straw. Treated straw (500 g DM/kg) was stored (56 days at 9.4°C in Experiment 1; 60 days at 9.6°C in Experiments 2 and 3) in sealed polythene bags before feeding. In Experiment 1 with 8 lambs/treatment, daily intakes of digestible straw organic matter per kg live weight (g DOM/kg W day −1) were: untreated straw, 5.7; 30 g urea/kg straw DM, 5.8; 30 g urea and 30 g Ca(OH) 2/kg straw DM, 6.9; 30 g urea and 60 g Ca (OH) 2, 8.7; 60 g urea and 60 g Ca (OH) 2, 9.4. In Experiment 2, using 48 lambs, straw intakes were higher. Intakes of g DOM/kg W day −1 were: untreated, 8.0; 60 g Ca(OH) 2, 11.2; 15 g urea and 60 g Ca(OH) 2, 12.2; 30 g urea and 60 g Ca(OH) 2, 13.7. In Experiment 3, using 12 lambs/treatment, with straw intakes at 13.7 g organic matter (OM)/kg W day −1, straw OM digestibilities (g/kg) were: untreated, 485; 60 g Ca(OH) 2, 575; 15 g urea and 60 g Ca (OH) 2, 585. No mold was encountered in any treated straws. Treatment with 30 g urea and 60 g Ca (OH) 2 was considered optimum as it maximised intake of digestible straw. An unexpected finding was that urea hydrolysis during storage was reduced in the presence of Ca (OH) 2.

Root canal dentinal tubule disinfection

Dentinal tubules of the root canal walls of human teeth were infected in vitro with a known bacterial isolate. The roots were exposed to either calcium hydroxide or iodine potassium-iodide for various periods of time and the viability of microorganisms was determined by incubation of entire root samples in a culture medium. The effects of the two agents on microbial viability were evaluated and compared. Iodine potassium-iodide disinfected dentin effectively. In contrast, bacteria remained viable in the dentin after relatively extended periods of calcium hydroxide treatment.

An enzyme histochemical study of the influence of formocresol and calcium hydroxide on the dental pulp.

Abstract Sections of goat incisor pulps were studied after a 5‐min application of formocresol (FC) or after calcium hydroxide or saline/ZnOE treatment followed by freeze‐sectioning. After 3–7 days the incisal part of the pulp was necrotic, as shown by absence of lactate dehydrogenase (LDH) activity. The necrotic zone was much larger after FC than after saline/ZnOE or calcium hydroxide. The LDH negative area after application of FC appeared to consist of a layer showing nuclei that were well‐preserved by the formaldehyde from the FC, and an area of tissue breakdown, which showed no or a reduced structure according to hematoxylin and eosin. Well‐preserved nuclei were not found in the 2 other groups. After 14 days all necrotic tissue, except that subjacent to calcium hydroxide, had been replaced by vital (LDH‐positive) tissue. After saline/ZnOE or calcium hydroxide treatment, hard‐tissue formation was found in all teeth, and after FC treatment in the majority of teeth.

Treatment of a maxillary canine with external inflammatory root resorption

This case report describes the treatment of a maxllary right canine with external inflammatory root resorption. Full instrumentation and long-term calcium hydroxide treatment were carried out. After 8 months and repeated changes of calcium hydroxide, a swelling developed in the buccal mucosa above the canine. Radiographs indicated that the inflammatory lesion adjacent to the resorption cavity had not healed, possibly because of the presence of anaerobic bacteria extraradicularly and inaccessibility to conventional endodontic therapy. The root canal was then obturated. A full-thickness flap was reflected, the granulation tissue was removed, and the resorption defect was repaired with an amalgam filling. Follow-up examinations indicated that the root resorption was arrested and periradicular repair was evident. This case report describes the treatment of a maxllary right canine with external inflammatory root resorption. Full instrumentation and long-term calcium hydroxide treatment were carried out. After 8 months and repeated changes of calcium hydroxide, a swelling developed in the buccal mucosa above the canine. Radiographs indicated that the inflammatory lesion adjacent to the resorption cavity had not healed, possibly because of the presence of anaerobic bacteria extraradicularly and inaccessibility to conventional endodontic therapy. The root canal was then obturated. A full-thickness flap was reflected, the granulation tissue was removed, and the resorption defect was repaired with an amalgam filling. Follow-up examinations indicated that the root resorption was arrested and periradicular repair was evident.

Experimentally induced lactic acidosis in the goat

Lactic acidosis was produced experimentally twice in each of 4 adult, female goats, by giving sucrose orally at the rate of 18 g/kg bodyweight. Changes in pH, osmolality, lactic acid concentration, and other constituents in ruminal fluid, plasma and blood were monitored over a period of 48 h. Also changes in urinary pH and sediment were examined. To ameliorate the metabolic disturbance, calcium hydroxide and bicarbonate treatment was employed after the 24 h samples had been collected and their acid-base status determined. A feature of the disturbance in the goats was that a metabolic alkalosis preceded the onset of lactic acidosis.

Effect of calcium hydroxide treated dentine on pulpal responses.

Summary. The purpose of the present study was to test the hypotheses that calcium hydroxide enhances pulpal protection against irritating substances in and around dental restorations when topically applied to cut dentine, and to acquire further information regarding the possible mechanisms involved. Cavities in dentine were treated for 30 days with either a water slurry of calcium hydroxide or a hard‐setting calcium hydroxide containing base. Control cavities were treated with saline. The additional effect of dry cutting prior to the restoration was also included as a control. Pulpal responses after placement of a silicate cement restoration were evaluated after an additional period of 30 or 150 days. From histological sections the volumes of inflamed pulp and the volumes of irregular secondary dentine were calculated with a morphometric method of evaluation. Changes in dentine to the calcium hydroxide treatment were observed with scanning electron microscopy. Most pulps in teeth with cavities treated with saline and restored for 30 days with silicate cement exhibited inflammatory alterations. Calcium hydroxide treated teeth had a significantly lower volume of inflamed pulp compared with the saline controls. Dry preparation was also associated with reduced inflammatory reaction. Pulps in teeth with dentine treated by the calcium hydroxide containing hard‐ setting base displayed the same magnitude of pulpal inflammation as the saline treated controls. After restoration for 150 days the volumes of inflamed pulp tissue were reduced in all treatment groups, however the least pulpal responses were found in teeth treated with calcium hydroxide slurry. Data also showed that the calcium hydroxide treatment was associated with only small volumes of irregular secondary dentine, while in contrast dry cut teeth showed large volumes of irregular secondary dentine. Scanning electron microscopic evaluation of dentine treated with calcium hydroxide revealed reticular structures inside the dentinal tubules