Treatment with paracetamol, ketorolac or etoricoxib did not hinder alveolar bone healing: a histometric study in rats

Abstract

Prostaglandins control osteoblastic and osteoclastic function under physiological or pathological conditions and are important modulators of the bone healing process. The non-steroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenase (COX) activity and consequently prostaglandins synthesis. Experimental and clinical evidence has indicated a risk for reparative bone formation related to the use of non-selective (COX-1 and COX-2) and COX-2 selective NSAIDs. Ketorolac is a non-selective NSAID which, at low doses, has a preferential COX-1 inhibitory effect and etoricoxib is a new selective COX-2 inhibitor. Although literature data have suggested that ketorolac can interfere negatively with long bone fracture healing, there seems to be no study associating etoricoxib with reparative bone formation. Paracetamol/acetaminophen, one of the first choices for pain control in clinical dentistry, has been considered a weak anti-inflammatory drug, although supposedly capable of inhibiting COX-2 activity in inflammatory sites.

Objective: The purpose of the present study was to investigate whether paracetamol, ketorolac and etoricoxib can hinder alveolar bone formation, taking the filling of rat extraction socket with newly formed bone as experimental model.

Material and methods: The degree of new bone formation inside the alveolar socket was estimated two weeks after tooth extraction by a differential point-counting method, using an optical microscopy with a digital camera for image capture and histometry software. Differences between groups were analyzed by ANOVA after confirming a normal distribution of sample data.

Results and conclusions: Histometric results confirmed that none of the tested drugs had a detrimental effect in the volume fraction of bone trabeculae formed inside the alveolar socket.

Figure 1

Rat alveolar sockets at 2 weeks after tooth extraction (hematoxylin and eosin; original magnification ×50). New bone trabeculae (*) forming from the inner surface of the lateral alveolar wall (LAW) in a control rat (A) and in rats treated with paracetamol (B), ketorolac (C) and etoricoxib (D); blood clot remnant (BC) interposed among new bone trabeculae in a ketorolac-treated rat

Figure 2

Percent of new bone trabeculae (mean±standard error of mean) inside the alveolar socket, 2 weeks after tooth extraction, in control (CON) rats and in rats treated with ketorolac (KET), etoricoxib (ETO) and paracetamol (PAR)