Local anesthesia is a precondition for the surgical insertion of implants. However, for some patients local anesthesia alone is not sufficient due to the extent of the procedure or the degree of dental or medical anxiety. In some instances, anxiety can be relieved using psychological support, for instance, acknowledgement of the patient's anxiety and explanation of the procedures prior to the treatment. Psychological support can be combined with sedation in the form of inhalation sedation, oral sedation, or intravenous sedation. For a few patients, general anesthesia should be considered. This module describes the local anesthetic techniques required for implant placement and the different kinds of sedation available to reduce the anxiety of the patient. This module has been made with assistance from Brian Lerche, MD, DEAA, MPA.

After completing this ITI Academy Module, you should be able to: classify patient health according to the American Society of Anesthesiology (ASA) Physical Status Classification System; describe the local anesthesia techniques used for implant placement; explain the indications and clinical guidelines for nitrous oxide (N2O-O2) sedation; explain the indications, appropriate drugs, and clinical guidelines for oral sedation; explain the indications, appropriate drugs, and clinical guidelines for intravenous (IV) sedation; and decide when a patient should be treated under general anesthesia.

Relieving the anxiety of the patient using different kinds of sedation requires that the patient is healthy. Before any surgical procedure a proper evaluation of patient health must be made. The American Society of Anesthesiology has devised a classification system describing the medical health of the patient: ASA Physical Status 1 is a normal healthy patient, ASA Physical Status 2 is a patient with mild systemic disease only without substantive functional limitation, ASA Physical Status 3 is a patient with severe systemic disease or a patient with one or more moderate to severe diseases, ASA Physical Status 4 is a patient with severe systemic disease that is a constant threat to life, ASA Physical Status 5 is a moribund patient who is not expected to survive without the pending operation, and ASA Physical Status 6 is a declared brain-dead patient whose organs are being removed for donor purposes.

Patients to be sedated in private offices must be classified as ASA Physical Status 1 or 2. A Status 2 patient could be a current smoker, social alcohol drinker, a pregnant or obese patient with a Body Mass Index between 30 and 40, a patient with mild lung disease or with well-controlled diabetes mellitus or hypertension.

Status 3 patients have severe systemic disease such as poorly controlled diabetes mellitus or hypertension, chronic obstructive pulmonary disease, active hepatitis, alcohol dependence or abuse, implanted pacemaker, moderate reduction of ejection fraction, end-stage renal disease undergoing regularly scheduled dialysis, history (more than 3 months) of myocardial Infarction, cerebral vascular accident, transient ischemic attack, or coronary artery disease or stents. Such patients can be treated in the dental office, but the systemic disease must be addressed first. The patient must be under treatment for the disease before sedation can be performed. Morbid obesity (with a Body Mass Index of 40 or greater) is a risk factor for sedation, and therefore obese patients are considered ASA 3 patients.

ASA Physical Status Classification System, Key Learning Points: Proper pretreatment evaluation should involve a comprehensive medical history. The ASA Physical Status Classification System should be used to classify patient health for sedation in private dental offices. Only ASA 1 and ASA 2 patients should be sedated in the dental office. An ASA 3 patient can be treated in the dental office, but the systemic medical condition should be treated first.

Achieving anesthesia for implant placement requires that the dentist have detailed knowledge of the anatomy of the orofacial region. Dental implant surgery involves both soft tissue and bone. The nerves innervating these structures in the orofacial region are branches of the trigeminal nerve. The trigeminal nerve is predominantly sensory, with the trigeminal ganglion lying at the base of the middle cranial fossa. Three large trunks originate from the ganglion: the ophthalmic nerve, the maxillary nerve, and the mandibular nerve. Branches of the maxillary nerve that may be anesthetized for implant placement include the nasopalatine nerve, greater palatine nerve, and the infraorbital nerve. Branches of the mandibular nerve that are important to dentistry are the long buccal nerve, lingual nerve, and the inferior alveolar nerve.

In general, there are two different injection techniques for local anesthesia: nerve block anesthesia and infiltration anesthesia. To achieve nerve block anesthesia, local anesthetic is deposited near the main nerve trunk, which is usually distant from the surgical site. In infiltration anesthesia, the anesthetic is administered immediately around the surgical site. Either technique should be preceded by application of topical anesthesia to reduce the discomfort associated with an injection.

The outer cortical bone covering the maxilla is comparatively thin and is porous in many areas. This facilitates diffusion of the anesthetic from an infiltration injection at the height of the mucobuccal fold to the target area, which is the location of the apex of the former tooth. This is in contrast to the compact cortical bone covering most of the mandible, where a mandibular nerve block technique is more effective than infiltration. It is only in the anterior part of the mandible that the bone lamina is as thin as in the maxilla and an infiltration may be effective.

The kind of local anesthetic agent used for implant surgery depends on the general health of the patient and on the kind of medication being taken by the patient. The clinician should select the type of anesthetic and mode of administration appropriate to the individual patient and planned surgical procedure.The most commonly used local anesthetic agents are lidocaine with or without epinephrine, mepivacaine without epinephrine, and articaine with epinephrine. If multiple implants are placed or a larger bone grafting procedure is performed, the patient can benefit from the use of a long-acting local anesthetic agent such as bupivacaine. The use of bupivacaine also depends of patient health and medication.

The maxillary nerve block is recommended for implants placed in the molar region and for sinus floor elevation procedures. The maxillary block must be supplemented with block anesthesia of the greater palatine nerves. If the zygomatic arch is well developed, administration of anesthetic via infiltration will be difficult.

For implants placed in the maxillary esthetic zone including the premolars, infiltration anesthesia on the buccal aspect is recommended, together with block anesthesia of the greater palatine nerves or, in the frontal area, block anesthesia of the nasopalatine nerve. If the needle is placed very high in the area of the infraorbital nerve, one could speculate that the infiltration anesthesia is in fact an infraorbital nerve block anesthesia, because the needle in this area is in close contact with the infraorbital nerve.

In the posterior mandible infiltration techniques are not always as effective as in the anterior mandible due to the difference in the cortical bone thickness. For implant placement in the molar areas, inferior alveolar nerve block anesthesia, including the lingual nerve, should be performed. In addition, buccal nerve anesthesia is required.

In the mandibular anterior area, including the premolars, buccal infiltration anesthesia can be performed together with infiltration of the floor of the mouth (or lingual infiltration) to anesthesize the lingual nerve. In the premolar area, deep placement of the needle could result in mental nerve block anesthesia due to the close contact of the needle to the mental nerve.

Local Anesthesia for Implant Placement, Key Learning Points: Bone structure differs between the maxilla and mandible and between the anterior and posterior regions; the efficacy of local anesthesia is affected by these differences. In the anterior maxilla and mandible, including the premolar regions, buccal and palatal or lingual infiltration anesthesia is usually effective. In the posterior maxilla and mandible, block anesthesia is usually required. Combined block and infiltration anesthesia may be required for more advanced surgical procedures.

Anxiety can be relieved by inhalation sedation using nitrous oxide in combination with oxygen. Nitrous oxide is a non-irritating, colorless gas with no significant smell. It has the effect of relieving anxiety and has some analgesic or pain-killing effect as well. However, nitrous oxide should not be considered as a form of pain control. The analgesic effect is generally insufficient for pain relief in most dental procedures, and local anesthesia must be performed after the gas has begun to take effect. After the gas is administered, the patient normally experiences a pleasurable feeling in contrast to oral sedation, where the patient normally feels drowsy. Guidelines and permit requirements for using nitrous oxide vary locally. In general, the surgical team must be educated in good work practices for the proper use of nitrous oxide sedation, its indications, and contraindications. The head of the clinic is responsible for the nitrous oxide equipment and its maintenance and is also responsible for preparation of the protocol for its use. In private dental offices the dentist should appoint a team member to be responsible for these tasks.

All components of the inhalation sedation unit should be inspected before use. This includes the flowmeters that control the precise flow of gasses delivered through the system so that there is never less than 30% oxygen concentration. The entire system should be tested for leaks. Leaks may be due to loose-fitting connections or defective or worn seals, gaskets, breathing bags, and hoses. The excess gas from the patient is collected and removed by a scavenging system. A commonly used type of scavenger system uses a double mask, as shown in this image. The scavenging system and double mask must be checked for intact connections, and an appropriate mask size must be selected for the patient. Prior to starting treatment, informed consent for inhalation sedation must be obtained. During nitrous oxide administration, appropriate monitoring of the patient is required. This includes use of a blood pressure monitor and in particular a pulse oximeter to measure the amount of oxygen saturation in the bloodstream. The patient should be instructed to breathe in and out through the nose, to lie still, and not to talk during the treatment.

Nitrous oxide can be used for normal healthy patients or patients with a mild systemic disease only. These patients are classified as ASA 1 and ASA 2. The primary indication for nitrous oxide is an anxious, fearful patient. Patients with an excessive gag reflex can also benefit from this treatment. Contraindications to treatment are allergy to nitrous oxide, patients with ongoing upper respiratory infection or obstruction who are unable to breathe comfortably through the nose, pregnant patients in the first trimester and patients with chronic obstructive pulmonary disease.

Some patients are not comfortable with the effect of the nitrous oxide, and some patients may experience claustrophobia and are unable to tolerate the mask. For those patients, oral or intravenous conscious sedation should be considered instead. Even though nitrous oxide apparatus is equipped with a scavenging system that removes the expired gas, some of the expired gas will stay in the area around the patient, which can affect the surgical team. Studies have shown that occupational exposure to nitrous oxide is associated with a higher risk of miscarriage, lowered fertility, liver and kidney diseases, and paresthesia. This justifies that the exposure of the staff should be minimized through effective scavenging systems, good ventilation, and proper maintenance of equipment to prevent leaks. Lastly, there is the problem of the slow degradation of nitrous oxide molecules in the atmosphere. Therefore, nitrous oxide should only be used when necessary.

Inhalation Sedation, Key Learning Points: Guidelines for use of nitrous oxide sedation vary. Administration of nitrous oxide requires education of the surgical team. Inspection of the equipment should be performed before every use. The patient must be given instructions before treatment. Indications include anxiety and excessive gagging. Contraindications include patients with an allergy to nitrous oxide, ongoing upper respiratory infections, patients who cannot breathe through the nose, patients in the first 3 months of pregnancy and those with chronic obstructive pulmonary diseases.

Oral sedation is a medical procedure involving the administration of oral sedative drugs to reduce the patient's fear and anxiety related to surgical treatment. Oral sedation can be used for patients for whom the various coping mechanisms are not sufficient to be able to participate in the treatment. The oral sedation drugs have no analgesic effects; therefore, local anesthesia still must be provided. During the sedation procedure, monitoring and emergency equipment such as a blood pressure monitor and pulse oximeter should be present. Guidelines for the administration of oral sedation vary locally. If in doubt, the surgeon must contact the local health authorities.

Prior to surgery, the patient must be seen for a preoperative examination. At that time, the patient should be classified according to the ASA Physical Status Classification System. It is also important to know what medication the patient is taking in order to decide the drug of choice for sedation. At the preoperative appointment, written consent for both the surgical procedure and the oral sedation must be obtained. It is important that the surgeon and patient discuss potential alterations to the planned treatment that might occur during the surgery. These potential alterations should be part of the informed consent. Once surgery begins, a sedated patient may not able to understand fully the implications of an alteration in treatment, and consent given by the patient in the midst of the surgical procedure may not be legal. At the preoperative appointment the patient must also be provided with written pre- and postoperative instructions. The patient must also be informed that he or she must be accompanied by an escort to and from the surgical procedure. The patient must not travel alone and must not drive himself or herself to the clinic.

Benzodiazepines are the most commonly used drugs for oral sedation. Diazepam or Valium, lorazepam or Ativan, and triazolam or Halcion are three commonly used benzodiazepine drugs. All benzodiazepines are central nervous system depressants. Their efficacy is equivalent to or greater than any of the other classes of sedatives, and they have a very good safety profile. However, the surgeon should be aware of potential interactions with other medication. The onset and duration of the clinical effects varies among individuals. The half-life period varies as well. The administration of the medication should be given at the dental office where the environment is controlled and monitored. The medication is given one-half to one hour before treatment depending on onset of the chosen drug. Some patients prefer administration of the medication the night before the procedure. Due to the drug's half-life period it may not be safe for the patient to drive themselves to the dental office in the morning.

Oral sedation using benzodiazepines is suitable for normal healthy patients or patients with a mild systemic disease only. These patients are classified as ASA 1 and ASA 2 patients. Oral sedation is indicated for patients with moderate levels of fear and anxiety. Benzodiazepines are contraindicated if the patient is allergic to the drug, has narrow-angle glaucoma, is pregnant, or is trying to become pregnant. Oral sedation is easy to perform and, if the right drug is chosen, this method is effective and usually well accepted by the patients. However, oral sedation may be ineffective in patients with higher levels of anxiety. For these patients intravenous sedation or even general anesthesia should be offered.

Oral Sedation, Key Learning Points: Guidelines for oral sedation vary locally. A comprehensive medical history of the patient is required. Only ASA 1 and ASA 2 patients should be treated with oral sedatives. Written consent must be obtained, and pre- and postoperative instructions must be given. Indications are for mild to moderate anxiety. It is contraindicated to use oral sedation if the patient is allergic to the drug of choice, is pregnant, or suffers from narrow-angle glaucoma. Benzodiazepines are reliable and safe drugs but may interact with other medication.

Intravenous or IV conscious sedation is performed by administration of sedative agents directly into the vascular system via an intravenous access. This level of sedation is appropriate for patients with higher levels of anxiety. As with inhalation and oral sedation, local anesthesia is still required. Performing IV conscious sedation requires advanced education and training; however, the legal guidelines regulating IV sedation and the degree of patient monitoring required vary locally.

Prior to the day of surgery, the patient must be seen for a preoperative evaluation. The patient should be categorized according to the ASA Classification System on the basis of their overall medical status. It is also important to know the patient's medication to ensure safe clinical practice when deciding upon the drug of choice for sedation. At the preoperative appointment, written consent for both the surgery and the IV sedation procedure must be obtained. As when oral sedatives are used, the surgeon and patient must discuss potential alterations to the planned treatment that might occur during surgery and include these potential alterations in the informed consent.

The patient must fast for 6 hours prior to treatment. This means no eating, no drinking and no smoking. After surgery, the patient must remain at the clinic until discharge criteria have been met. Patient must not travel alone and must not drive themselves home. Pre- and postoperative instructions should be given in writing.

Benzodiazepines are the most commonly used drugs. They reduce anxiety, make the patient feel sleepy, and produce partial amnesia. Benzodiazepines have a good safety profile, but interaction with other drugs can lead to adverse effects. Among other drugs used are opioids, barbiturates, and propofol. Opioids are strong pain killers and as such are effective drugs. However, opioids suppress respiration, thereby potentially establishing a dangerous situation if used in combination with benzodiazepines during IV sedation. Potentially, the patient can become unconscious.

Barbiturates are dangerous to use in the absence of a trained anesthesiologist and should not be used for IV sedation. Propofol is not a common sedative agent. It is used for general anesthesia where it is a good and reliable drug. It should be administered only by a trained anesthesiologist. The use of multiple drugs for IV sedation is performed in some countries, but controversies exist regarding this practice due to an increased risk of adverse effects.

IV sedation is for normal healthy patients or patients with a mild systemic disease only who are classified as ASA 1 and ASA 2 patients. Indications include patients with higher levels of fear and anxiety and those undergoing longer and/or more invasive procedures. It is contraindicated to use benzodiazepine if the patient is allergic to the drug, has narrow-angle glaucoma, is pregnant, or is planning to become pregnant. Obesity in combination with sleep apnea is a contraindication as well.

Performing IV sedation doubles the professional responsibilities of the surgeon. Although monitoring equipment is used, the surgeon must be vigilant regarding the condition of the patient. In addition, the surgeon has to concentrate on the surgical procedure itself. Giving the patient too much medication or choosing the wrong drug can result in respiratory depression, coma, or even death. The surgeon must have the skills to handle this situation. For this reason, depending on the situation, it may be advisable to consider using an anesthesiologist.

Intravenous Conscious Sedation, Key Learning Points: Guidelines for IV sedation and formal education of the surgeon vary. A preoperative examination of the patient is required. Only ASA 1 and ASA 2 patients should be considered for IV sedation. Informed consent must be provided before treatment. The patient must fast for 6 hours before treatment. Indications include higher levels of anxiety and longer, more invasive procedures. It is contraindicated to use IV sedation if the patient is allergic to the drug of choice, is pregnant, suffers from narrow-angle glaucoma, or is obese in combination with sleep apnea. Benzodiazepines are reliable and safe drugs when not mixed with other drugs, but monitoring equipment is required.

When there is no other method of pain and anxiety management appropriate for the patient, or when longer, more invasive procedures are to be performed, general anesthesia should be considered. Guidelines for administrating general anesthesia vary from country to country. In some countries it is possible to treat patients under general anesthesia in the dental office. However, general anesthesia is limited to hospitals or specialized clinics where the necessary monitoring and emergency equipment is available. Specialized training in anesthesiology is required to perform general anesthesia. If general anesthesia is to be performed in the dental office, only normal healthy patients or patients with a mild systemic disease should be considered. These patients are classified as ASA 1 and ASA 2 patients. In this scenario, the anesthesiologist performing the general anesthesia is responsible for supplying and maintaining the equipment. In a hospital setting, it is possible to treat ASA 3 patients, but preferably the patient's systemic disease should be treated first. Obese patients are considered to be ASA 3 patients.

A preoperative examination must be performed. This includes an accurate, clearly recorded medical history including present and past illnesses, drug allergies, and current medication and dose. The patient should be classified according to the ASA scale. Some offices require laboratory tests, chest x-rays, and electrocardiography before general anesthesia. The patient must be informed about both the surgical treatment and the general anesthesia procedure. The surgeon and patient must discuss possible alterations of the treatment potentially occurring during the surgery. Written consent must be signed beforehand.

The patient must fast 6 hours before treatment. This means no eating, no drinking, and no smoking. This is to prohibit vomiting during intubation of the airways. After treatment the patient must remain at the clinic until discharge criteria are met. The patient will need an escort home and must not be left alone for the remainder of the day. Pre- and postoperative instructions should always be given in writing.

Although general anesthesia controls both anxiety and pain, challenges exist when performing implant surgery in a patient under general anesthesia. Often the tongue is brought forward either by the airway tubing or by the use of a throat pack. This can make implant insertion in the mandible difficult. The problem can be reduced by training the surgical team to hold the tongue aside. Because the patient is unconscious and the muscles are paralyzed it is not possible to ask the patients for their cooperation. Taking radiographs during the surgery may also be a challenge because the patient is not able to help hold the film.

General Anesthesia, Key Learning Points: General anesthesia should not be used if other sedation methods are possible. General anesthesia in an outpatient setting is indicated only for ASA 1 and ASA 2 patients. ASA 3 patients may be treated in a hospital setting. Specialized training is required to perform general anesthesia. The patient must fast 6 hours before general anesthesia is induced. The patient must not travel alone after treatment. The patient must not be alone for the rest of the day.

Oral Anesthesia and Anxiety Control for Implant Surgery, Module Summary: The majority of implant surgery procedures are performed in the dental office under local anesthesia. The choice of local anesthesia technique depends on the bone structure in the surgical area and the planned procedure. Selection of the appropriate sedation technique should be chosen according to the patient's level of anxiety and the planned procedures. Sedation and general anesthesia may be performed in ASA 1 and ASA 2 patients in an outpatient setting; ASA 3 patients usually require a hospital setting. Sedation and general anesthesia guidelines for monitoring and formal education of the surgeon vary significantly; the surgeon must be aware of local rules and regulations. General anesthesia is an option only if conventional sedation procedures are not sufficient to mitigate patient anxiety.