Capping of the dental pulp mechanically exposed to the oral microflora – a 5 week observation of wound healing in the monkey

Abstract

The healing capacity of mechanically exposed and bacterially contaminated dental pulps was assessed in monkeys after capping with 2 commercial Ca(OH)2 containing compounds. One hundred eighty teeth in 7 monkeys were employed, 45 as untreated controls and 135 as treated exposures. Class V buccal cavity preparations resulting in pulpal exposure were prepared, left open to the oral cavity for 0, 1, 24 h or 7 days and employed as controls, or debrided, capped, restored with amalgam and left undisturbed for 5 weeks as treated exposures. Zero and 1 h untreated exposures presented damage from the mechanical trauma only, whereas 24 h and 7 day pulp wounds exhibited pronounced infiltrations of polymorphonuclear and mononuclear leukocytes. In addition, the 7 day exposures demonstrated several teeth with partial and total necrosis. Treated 0, 1 and 24 h exposures demonstrated wound healing, minimal pulp tissue inflammation, reorganization of soft tissue and formation of new hard tissue at the exposure site in 86 of 99 teeth. Treated 7 day exposures healed less frequently, showing signs of dentin bridging in 15 of 27 teeth. This study indicated that mechanically exposed and orally contaminated dental pulps in monkeys have a high capacity to resolve inflammation and initiate healing with new dentin formation at the exposure site when treated as described.

Success rate of calcium hydroxide pulpotomy in primary molars restored with amalgam and stainless steel crowns

“…3,5,9,13,32,41 Moreover, it has been emphasised that even in cases where bacterial contamination exists, the bacteria is unable to penetrate deep enough into the healthy pulp to prevent it from healing itself. 46 This capacity for self-healing appears to be the main determinant of clinical outcome in the mechanically exposed group. In both cariously exposed groups 1 and 2, pulpotomy success rates were higher for teeth restored with SSCs than for teeth restored with amalgam.…”

“…35 Numerous studies have shown that ZOE, which was used in this study as a base material, has good sealing ability and antibacterial properties. 1,8,32,46,49,50,56 It may therefore be suggested that ZOE used under restorations may prevent bacterial contamination either through its sealing ability and/or its antibacterial properties.…”

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“…It is the state of the pulp and the degree of bacterial contamination that enters the pulp, rather than the size of the exposure, that largely determines the prognosis of pulp capping (33,34). The technique with which the exposure is created may also affect pulpal healing.…”

“…In animal studies, mechanical exposure of the pulp followed by exposure to the oral environment for up to 24 h could be successfully capped (29,33,34), although healing took longer (29). A study in monkeys indicates that when the pulp is exposed to the oral environment for more than 24 h before capping, the prognosis declines (34), because bacterial contamination becomes excessive, although a more recent study in monkeys where pulp exposures were left untreated for up to 7 days stifl healed successfully (36).…”

“…In a similar study in dogs (39), the use of a zinc oxide-eugenol lining to exclude bacterial microleakage resulted in 60% more dentine bridges formed across the exposure. Cox et al (34,41) have demonstrated in a series of studies that when bacterial microleakage is poorly controlled, although initial results can be encouraging (34), the pulp may finally succumb in the longer term (41). In humans, pulp exposures in cavities cleaned with Tubulicid® and restored with unlined composite resin overlayed with zinc oxide-eugenol remained vital and showed no signs of inflammation (42).…”