-The response of the dental pulp to calcium hydroxide has been well described but the process of pulpal repair leading to dentinal bridge formation appears complex and the mechanisms remain incompletely understood. Through the precise regulation of the free calcium ion in the cytosol, cells have been able to utilize anions such as phosphates for a wide range of activities such as energy production (oxidative phosphorylation). As anions are abundant in the cytosol, intracellular levels of calcium ions are kept low, several orders of magnitude less than that of the surrounding extracellular matrix. Consequently, cells are able to use calcium ions for the regulation of many cellular events. The binding of extracellular molecules such as cytokines, hormones or antibodies, with receptors on the plasma membrane may result in short-or long-term modifications to cellular metabolism, including the mechanisms of intracellular calcium homeostasis. Cell survival depends upon the ability to adapt to changes in the cell's micro-environment. Adaptation in turn results in altered cellular activity that may be interpreted as showing that the cell has become more or less specialised. In some instances this may include the resumption of mitotic activity. If the rate or magnitude of change exceeds a cell's adaptive capacity, the cell dies. Responses of cells to alterations in their environment are reviewed as they may provide an explanation for the success of calcium hydroxide in facilitating pulpal repair and the differentiation of odontoblasts.

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Fracture patterns of contralateral pairs of intact and restored premolar teeth were determined after dynamic loads of equal energy were applied to the medial aspects of the buccal cusps. The predominant fracture path for intact teeth ran obliquely from the occlusal fissure to the buccal cervical region, followed by fractures from the point of impact. Most teeth restored with MOD amalgams fractured from the base of the cavity, whereas those with amalgam overlays suffered less severe fractures, sited higher in the cusps. When teeth restored with MOD gold overlays and full gold crowns fractured, the site was frequently in the root. The value of cuspal protection by means of overlay techniques was confirmed by this study.

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The healthy pulp has good healing potential when it is exposed, although the exact repair mechanism is still undetermined, and it is not material‐specific. Calcium hydroxide appears to promote the healing process and is the most widely accepted capping material. Paste‐type calcium hydroxide formulations are more consistent in promoting healing of pulp exposures than cement forms where bacterial microleakage is eliminated. The prognosis for pulp capping with calcium hydroxide is good if the pulp has no pre‐existing symptoms of pain, and the environment provided for it is suitable. This requires the absence of blood clots and bacterial contamination. Where there are some symptoms of pain in a vital tooth, pretreatments with suitable materials improve the prognosis.