Among the adjuvants to local anaesthetics (LA), the enzyme hyaluronidase is most often used as a diffuser agent of the LA in ophthalmic anaesthesia. It serves to improve clinical efficacy and prolong anaesthesia as an alternative to long-lasting and potentially more dangerous LA, especially in patients with increased cardiovascular risk. There is scarce clinical data about the safety of the use of hyaluronidase in dental procedures.

This study aimed to compare hemodynamic and electrocardiographic variables during a dental surgical procedure using a local anaesthetic associated with hyaluronidase or placebo in healthy subjects.

This double-blind crossover "split-mouth" trial evaluated the cardiovascular effects induced by 3.6 mL of the LA 2% HCl mepivacaine with 1:100,000 epinephrine, concomitantly with 75 TRU/mL hyaluronidase or placebo in inferior alveolar nerve block, for the performance of bilateral and symmetrical third molar surgery in 20 outpatients. Cardiovascular parameters, including systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR), were monitored using oscillometric and photoplethysmographic methods in 10 clinical stages. Electrocardiographic records (ECG) of 12 leads were obtained in four steps. Hyaluronidase injected concomitantly with LA did not induce changes in SBP, DBP and HR compared to placebo. There were no instances of ST segment depression, ST segment elevation, wide QRS complex extrasystoles, or narrow QRS complex extrasystoles.

To date, few studies in dentistry have investigated the effects of local anaesthetic efficacy in hyaluronidase, and even fewer have studied the relation to systemic effects induced by this interaction.

The use of LA injected concomitantly with 75 TRU/mL of hyaluronidase is safe when using this dose and route of administration.

Clinical Relevance: In dentistry, few studies have investigated the effects of hyaluronidase on local anaesthetic efficacy, and even fewer have examined the possible systemic effects induced by this interaction.

Inclusion Criteria:

• Patients should present bilateral lower third molars (teeth 38 and 48) for extraction and identical anatomical arrangement;
• Absence of significant clinical morbidities, ASA I (American Society of Anesthesiologists, 1963);
• Aged over 18 years.

Exclusion Criteria:

• Women during pregnancy or lactation;
• Smokers;
• History of sensitivity to any drug used in the research;
• Presence or history of cancer or an infectious lesion;
• Individuals who used any medication in the last 15 days (except oral contraceptives);
• Presence of abscess or pericoronitis in the region to be operated;
• Patients who required supplemental anaesthesia upon anaesthetic block of the inferior alveolar nerve (post-randomisation exclusion).