The goal of this clinical trial is to compare two groups of patients going in general anesthesia for intraoral surgery, the first group TIVA with propofol and the second group inhalational with sevoflurane. The main questions it aims to answer are to asses speed and quality of recovery from general anesthesia.

Participants will fill out a questionnaire to evaluate the quality of recovery from anesthesia using the QoR-40 1h, 24h, and 30 days after waking up from anesthesia in comparison to the results of the same questionnaire before surgery. Also, the investigators will perform a hand grip and bite strength test on the patients after waking up from anesthesia in the operating room, after 1 hour in the recovery room, and after 24 hours compared to preoperative values.

The investigators will compare TIVA and Volatile groups to see if there are any differences in recovery seed, muscle strength recovery, postoperative nausea and vomiting, and shivering between groups.

After obtaining the approval of the ethics committee of KBC Zagreb and the Faculty of Dentistry of the University of Zagreb, the research will be conducted at KBC Zagreb.

Criteria for patient inclusion are:

• patients older than 18 years
• ASA status 1-2,
• Patients who have an indication for an intraoral surgical procedure (intraoral tumor excisions) longer than 30 minutes.
• patients who agreed to the research and signed the consent

Exclusion criteria are:

• ASA status 3 and higher,
• The need for postoperative care in the ICU,
• Surgery lasting more than 2 hours,
• Surgical procedures that in the operative plan include injuries to the grip of the masticatory muscles, the masticatory muscles themselves, and procedures on the bone, and thus may result in a difference in the strength of the bite. Masticatory muscles are defined as musculus pterygoideus lateralis, musculus pterygoideus medialis, musculus temporalis and musculus masseter.
• Surgical procedures on the bone where the bite force test alone could cause injury
• Patients with diseases of the neuromuscular junction and muscle diseases, myopathy, dystrophy
• Patients taking medications that can cause myopathy or muscle weakness
• Known allergies to drugs used in the trial,
• Refusing to participate

Participants will be randomly divided (1:1 randomisation) according to a predetermined randomization table (32) into the TIVA group and the Volatile group. After identification of the participants in the operating room, participants will be fitted with a peripheral venous line, electrocardiogram monitoring, non-invasive blood pressure measurement, pulse oximeter, capnograph, temperature probe, and bispectral index (BIS) of the electroencephalogram and neuromuscular monitoring, kinemiography with train-of-four (TOF , M-NMT, Drägerwerk AG & Co. KGaA,) by recording the responses.

The initial anesthesiological induction procedure will not differ in both groups of patients. The drugs that will be used are sufentanil 0.3mcg/kg, propofol 2mg/kg, and cisatracurium 0.1mg/kg.

Participants will be intubated with an endotracheal tube and mechanically ventilated with a mixture of oxygen and air (inspiratory fraction of oxygen 40%) with a total flow of gas mixture of 3 L/min.

Anesthesia will be maintained in the volatile group with the inhaled anesthetic sevoflurane and single doses of cisatracurium. Cisatracurium will be repeated when the TOF ratio is greater than 5%, and the repeat dose will be 0.01 mg/kg. The depth of anesthesia will be controlled by BIS, maintaining values between 25 and 50. Recommended drug doses will be guided by TOF and BIS values.

In the TIVA group, anesthesia will be maintained with a continuous infusion of propofol (5-10 mg/kg/h) and single doses of cisatracurium. Cisatracurium will be repeated when the TOF ratio is greater than 5%, and the repeat dose will be 0.01 mg/kg. The depth of anesthesia will be controlled by BIS, maintaining values between 25 and 50. Recommended drug doses will be guided by TOF and BIS values.

At the end of the surgical intervention in both groups, the neuromuscular block will be antagonized with prostigmine (0.05 mg/kg) along with atropine (0.01 mg/kg) as soon as the patient begins to breathe spontaneously. Patients will then be extubated when the TOF index is greater than 90%

Muscle strength of all participants will be measured with a JAMAR hand dynamometer, and bite force with a gnathodynamometer (Bite force sensor, Monad electronics) in four time intervals:

1. Before introduction to anesthesia
2. After waking up from anesthesia in the operating room
3. 1 hour after waking up from anesthesia in the recovery room
4. After 24 hours from the operation

All patients will fill out the Quality of recovery-40 (Qor-40) questionnaire for assessing the quality of recovery after anesthesia and surgery in four time intervals:

1. Before introduction to anesthesia
2. 1 hour after waking up from anesthesia in the recovery room
3. After 24 hours from the operation
4. After 30 days from the operation Consent for the use of the QoR-40 questionnaire was obtained by the main researcher from the author, Professor P.S. Myles, and Dr. M. Miklić Bublić, who translated the questionnaire into Croatian.

Postoperative nausea and vomiting and postoperative shivering will also be recorded, as a binary outcome (yes/no), by visual assessment and interaction with the patient.

The time from the end of the operation to waking up will be monitored. Pain will also be recorded based on QoR40 and the visual analogue scale (VAS-scale) for pain assessment. The patient's chronic therapy is recorded, as is the need for postoperative analgesia.

Assuming medium to large effect size, test power of 80% and use of independent t-test for the primary objective and x2 test for the secondary objective with a statistical significance of 0.05, it is necessary to take a sample of 42 patients, 21 subjects per group. . The test for power calculation is G Power Version 3.1.9.6 (46). Assuming that part of the respondents will not be able to follow up until the end of the research, a sample of 50 patients will be taken, that is, 25 patients in each group. A review of similar studies confirmed the sample size (18,47,48). The results will be processed with IBM SPSS statistics v27. For scalar parametric data, the independent Student t test will be used, for non-parametric data, the Mann-Whitney U test, while categorical data will be processed with the Pearson χ² test. One interim analysis for feasibility and precision estimation is planned.

Criteria for patient inclusion are:

• patients older than 18 years
• ASA status 1-2,
• Patients who have an indication for an intraoral surgical procedure longer than 30 minutes.
• Surgical interventions on the soft tissues of the mouth, intraoral excision of tumors, operated through the transoral route
• Patients who agreed to the research and signed the consent

The exclusion criteria are:

• ASA status 3 and higher,
• The need for postoperative care in the ICU,
• Surgery lasting more than 2 hours,
• Surgical procedures that in the operative plan include injuries to the grip of the masticatory muscles, the masticatory muscles themselves, and procedures on the bone, and thus may result in a difference in the strength of the bite. Masticatory muscles are defined as musculus pterygoideus lateralis, musculus pterygoideus medialis, musculus temporalis and musculus masseter.
• Surgical procedures on the bone where the bite force test alone could cause injury
• Patients with diseases of the neuromuscular junction and muscle diseases, myopathy, dystrophy
• Patients taking medications that can cause myopathy or muscle weakness
• Known allergies to drugs used in the trial,
• Refusing to participate

If there is a need and desire on the part of other researchers, data on patients without personal data can be shared