Effectiveness of benzocaine in reducing deep cavity restoration and post-extraction stress in dental patients

Objectives:

To investigate the effectiveness of topical anesthetic, 20% benzocaine in relieving pain and stress in patients following deep cavity restoration and extraction of teeth under local anesthesia (LA).

Methods:

A prospective clinical trial was conducted from October 2014 until April 2015 at Taibah University, Al Madinah Al Munawarah, Kingdom of Saudi Arabia. Forty-five patients were included in the 20% benzocaine group, and 46 in the normal saline group. Evaluation of the dental stress was made pre-operatively and immediately post-operative treatment using the visual analogue scale (VAS). Furthermore, discomfort of the injections were recorded by the patients after each treatment on standard 100 mm VAS, tagged at the endpoints with “no pain” (0 mm) and “unbearable pain” (100 mm).

Results:

There were statistically significant differences between the mean stress scores for patients in the benzocaine and normal saline groups post-operatively (p=0.002). There were significant differences between the mean pain scores for patients in the post buccal injection (p=0.001), post palatal injection (p=0.01), and the post inferior alveolar nerve block groups (p=0.02). Buccal, palatal, and inferior alveolar nerve block injections were more painful for patients in the normal saline group than the benzocaine group.

Conclusion:

This investigation has demonstrated that post-operative stress associated with deep cavity restoration and dental extractions under LA can be reduced by the application of topical anesthetic (20% benzocaine) at the operative site for intra-oral injections.Anxiety is one of the most common causes of dental fear.1 There have been 3 stable and reliable factors, which contribute to dental fear. The first factor is related to patterns of dental avoidance and anticipatory anxiety, the second, related to fear, which is associated to specific dental stimuli and procedures, and the third is concerned with physiologic arousal during dental treatment.2 Fear develops through the interaction of 3 phenomena, those which are instinctive, dependent on maturation, and developed through learning from individual and social experience.3 It is unusual for modern local anesthetics to fail completely unless they have been injected incorrectly, but it is common for patients to retain some sensation of pressure around the tooth. Dental stress and anxiety may lead them to interpret this as pain, and cooperation is lost.4,5 Application of topical anesthetic for post-operative pain relief has not usually been considered as a part of routine clinical dental practice. However, infiltration local anesthesia (LA) has been used in other surgical disciplines with good effect.6,7 The field of anesthesia has witnessed many developments throughout the last century, and a number of different techniques and agents have been developed. Anesthesia has become an essential procedure in every surgical operation and treatment. In practice, topical anesthesia including cocaine, amethocaine, lignocaine, and prilocaine is applied to skin, eye, ear, nose, and mouth. Their application was reported to be useful and effective for reducing pain sensation.8 When used to produce topical anesthesia, they usually have a rapid onset of action (5-10 minutes mins]), and a moderate duration of action (30-60 mins). A rapid onset of action of 5 mins or less has also been reported for 10% and 20% benzocaine gels for the relief of spontaneous toothache pain.9 Various preparations of lignocaine are available as aqueous solutions (4%), or in water-miscible bases, such as gels, ointments, creams, and sprays (2-10%). Intact skin works as a barrier preventing the diffusion of local anesthetics so high concentrations of anesthetic agents (for example, 20% benzocaine or 4% lignocaine) are required.8 The use of LA in dentistry is standard practice. No studies were found in the literature, which looked at the possibility of using benzocaine soaked rolls/swabs to reduce the post operative stress in adult patients following simple dental extractions, or deep cavity restoration. This study concentrated on the effectiveness of topical anesthetic 20% benzocaine for relieving pain of local anesthetic injection, and post-operative stress in patients following extraction of teeth, or deep restoration under LA.