11th International Dental Congress on Modern Pain Control The Essential Role of Dental Anesthesiology in the 21st Century Safe and Comfortable Dentistry 4th–7th October, 2006

Abstract

There is no global standard for the concept of dental anesthesiology. The definition of the specialized field of dental anesthesiology differs among the countries of the world depending on educational curricula and laws. For this reason, I will begin this lecture with a brief summary of the dental medical system and undergraduate education in Japan. I would then like to talk about the roles that dental anesthesiology should play in dentistry in the future.Japanese schools of dentistry have set up departments of dental anesthesiology in the same way that they have departments of orthodontics, prosthodontics, and oral surgery: that is, based on authorization by the Ministry of Education, Culture, Sports, Science, and Technology. The dental anesthesiology departments are organized in such a way that the staff is engaged in student education, research, and clinical practice in hospitals. Dental anesthesiology is thus an independent, specialized, and systematic academic discipline, and it functions as a core department at dental hospitals.The educational curriculum for students of dental anesthesiology consists of general management, methods of anesthesia (local anesthesia and general anesthesia), sedation, emergency treatment procedures, cardiopulmonary resuscitation, and treatment of orofacial pain. This educational curriculum mirrors precisely clinical practice in departments of dental anesthesiology.The Japanese Dental Society of Anesthesiology was established in 1972, and now has over 2000 members. The Society has systems for accreditation of dental anesthesiology and the specialty of dental anesthesiology. There are currently 800 accredited dental anesthesiologists and 200 specialists in dental anesthesiology. It became legal to use the phrase “specialist recognized by the Japanese Dental Society of Anesthesiology” in advertisements from July, 2006. Other specialists include those in oral surgery, periodontics, and pediatric dentistry. It is hoped that many other specialized academic societies in dentistry gain accreditation from the Ministry of Health, Labor, and Welfare. The practice of dental anesthesiology as a clinical specialty is chiefly performed at hospitals associated with schools of dentistry. Only a small number of Society specialists work at general hospitals, where they treat dental patients as specialized anesthesiologists, although there are no departments of dental anesthesiology at these hospitals. There are dental centers around the country run by local dental associations and financially supported by local municipalities for the purpose of dental treatment for the disabled, home-bound elderly, and other such patients. Society specialists and accredited dental anesthesiologists perform general management and sedation through monitoring to ensure the safety of high-risk patients for medical emergencies at such centers. Many anesthesiologists accredited by the Japanese Dental Society of Anesthesiology practice general dental medicine at their own clinics.In Japan, dentists are only permitted to administer general anesthesia to dental patients. The reason dental anesthesiology departments were established at schools of dentistry was that oral surgery could be performed under general anesthesia administered by a dentist. This was roughly 40 years ago. However, since the range of applications to dental patients of the knowledge and techniques of general anesthesia is extremely broad, the scope of practice of dental anesthesia has also broadened in accordance with the needs of dental outpatient departments in university hospitals. These include, for example, general management through monitoring to prevent emergencies in medically compromised patients (194 cases), relief of anxiety and tension as well as behavioral control for the disabled through intravenous sedation (1634) cases, day anesthesia mainly for dental treatment for the disabled (143 cases), in-hospital emergency treatment procedures (180 cases in 10 years), and procedures in pain clinics (2512 cases). The figures in parenthesis refer to the number of cases per year at Tokyo Dental College Chiba Hospital.There are also 800 cases of use of general anesthesia per year, mainly for oral surgery, at that Hospital.As I'm sure you know, the proportion of the elderly in the general Japanese population is large and growing at an incredible rate. One goal of the dental care policy of the Ministry of Health, Labor, and Welfare is to maintain 20 teeth at the age of 80. This policy has been in place for 20 years now, and the percentage of elderly individuals who have retained their own teeth is on the rise, and for this reason, an increasing number of the elderly receive dental treatment. Dental treatment for medically compromised patients, particularly those with high blood pressure, ischemic heart disease, and cerebrovascular disease, which are particularly prevalent in Japan, is increasing in frequency. A simple dental procedure could become a stressor that proves fatal to these patients, meaning that prevention of medical emergencies, risk evaluation, and general management are increasing in importance.In a nationwide study of medical emergencies in dental patients in Japan, it was reported that stressors caused by pain and tension were the main sources of danger to dental patients. If effective general management can be performed by minimizing fluctuations of autonomic nervous system activity due to pain and tension, then, with the exception of acute systemic illnesses, there will be no contraindications to dental treatment, even in high-risk patients. The anesthetic and physiological effects of local anesthesia with vasocon-strictors, cardiovascular fluctuations and their reduction through intravenous sedation during dental treatment, the cardio-respiratory effects of sedation, the differences in the process of recovery associated with different methods of sedation, criteria for discharge from the dental office, etc., are all important themes of research in dental anesthesiology, and continuous research is required for every new drug introduced. Since everyday clinical practice must be based on the results of research, i.e. evidence-based medicine, one of the advantages of having a dedicated department is that research, education, and clinical practice can proceed in unison.The pursuit of safety and comfort in dental treatment is the basic driving force behind increasing the level of quality of dentistry. As persons involved in dental anesthesiology, I believe that our role is to achieve high degrees of specialty for this purpose, whether it is in constructing systems of research, education and training, or general anesthesia, intravenous sedation, pain clinic duties, general management of high risk patients, or other aspects of clinical practice. It is certain that the role of dental anesthesiology will grow in importance in the future in Japan in proportion to the expected increase in need for dentists for oral health care for terminal patients in hospitals and homes.I believe that responding to the current desires of people regarding dental medicine from the standpoint of dental anesthesiology will allow us to fulfill future roles as dental practitioners in the 21st century. Furthermore, I believe it is necessary to look again at the past, when 160 years ago the two American dentists Wells and Morton were the key players in the discovery of anesthesia. Painless and comfortable dental treatment is a hope that is common to everyone in the world, regardless of nationality. I believe that cooperation that transcends national boundaries among those of us involved in dental anesthesiology, despite differences in systems of dental medicine or education, will be the major driving force that helps us propel dental medicine forward towards that common goal.Tissue engineering is relatively a new approach for regenerative medicine. According to the concept, human body can be regenerated by using stem cell, scaffold and growth factors. Among the several medical fields, dentistry or cosmetic surgery are the advantageous field for the therapeutic use. Since 1984, we have developed the several kinds of the tissues and organs using cultured living cells by Tissue Engineering Concept. In my lecture I will present bone and skin regeneration, because they are thought to be the most hopeful and clinically available tissue in near future.The first topic is ridge augumentation for implant surgery. In case of implant denture, bone availability is the key to successful placement of endosseous implants in the posterior maxilla. When the thickness of the bone between the sinus and alveolar crest is less than 5 mm, increasing the thickness of the sinus floor through grafting is necessary to support the required long fixtures. To provide adequate viable bone, many kinds of graft materials has been investigated and introduced for clinical use. Among them, autogenous bone grafting is the most predictable and well-documented surgical approach. Another graft materials, such as allogenic and heterogenic materials has a risk of disease transmission. And synthetic material has a poor osseogenesity, so it can not replace the entire function of living tissue. We have developed the injectable bone using MSC and PRP. The injectable bone is an expected method of cell delivering system for the bone regeneration with the advantages of minimum invasiveness and fitness in the defect. In our animal study the MSC and PRP admixture could be injected by the needle into the subcutaneous space.We have applied the injectable bone in 15 patients and evaluated at 3 years after the first surgery. Forty five fixtures were installed with injectable bone and all implants succeeded to osseointegration clinically. Radiographic evaluation showed that mean increase in mineralized tissue was 7 mm. The main complications during surgery was sinus membrane perforation. However there was no abnormal sign in sinus and maxillary region during total observation period.The next topics is the skin rejuvenation therapy in perioral region. In the past, skin wrinkle have been treated with injectable bovine collagen, Botox R and hyalonic acid gel. However, they are very short lived about 3M, and one percent to 6% of patients receiving such materials injection may develop a localized nerve paradysis, temporary erythema, induration, and swelling. On the other hand, our fibroblast system provides no abnormal reactions with long action, about 3 years. Because it is antogenous cell.The fibroblast with saline solution was injected with a 30-gauge needle into the superficial dermal junctions. The fibroblast can survive and produce collagen locally and correct the wrinkle for more than 3 years. In our clinic, 20 patients were treated by our system. Mainly, perioral and nasolabial folds, were treated. Improvements were evaluated by pre- and post injection photographs at 3 months intervals thereafter. As a result, 90% of patients show the satisfactory improvement even in 3 years.The tissue engineering therapy in implant treatment can provide the patient the higher esthetic result and satisfaction. It opens a new window for implant surgeons.Mind to Promote Science—Science for People and Its Society Jun-ichi Nishizawa, PhD, President, Tokyo Metropolitan University, JapanDevelopment of science and technology started in Greece in the age of Aristotle, most famous story is the finding of law of buoyancy by Archimedes to detect the admixture doped into the gold of crown, which is the early application of science for the human business.On the other hand, in Asia, legendary ancient emperor Shin and Fukki licked many sorts of natural plant and classified into poison, food and medicines for the people, and is thought to be the beginning of biochemistry.Afterwards, science and technology in Europe, produced a lot sorts of devices and treatment mainly weapons and finally production of connono̊ which could not be followed by Asian workman and scientist. In Asia, Chinese have been so much proud of the invention of magnet: c compass, gun powder and wooden printing type, however, field of science and technology should siege much wider including bioscience, biotechnology, which has advanced in Asia.Fundamental idea of science and technology in Asia has been represented in Chinese character, which is “I” and the top horizontal shorter bar represents the donation from the God; sun shine, wind, rain and natural resources. And the lower longer horizontal bar corresponds to the people and society on the earth. And along the vertical bar, make use of the donation toward the happiness of the human beings and the society is the essence of the science and technology.Now a days, the accumulation of the carbon dioxide in the air surrounding the surface of the earth changing the climate and deposited carbon in the form of hydro methane at the bottom of deep water seems to be saturated and suggesting the explosion which seems to induce the temperature rise because of the increase of the carbon dioxide.We thought the leaving from the fossil fuel, human being can never be alive. D.C. power transmission can realize 20 thousand kilometer transportation and our original semiconductor transformer, which can be realized by the connected D.C. to A.C. converter, A.C. higher frequency, as an example 20 kHz, transformer and A.C. to D.C. converter or pin diode in series realize 98% efficiency as a whole as a D.C. voltage transformer, and can realize 1MV electrical energy sending system with thin conducting wire. Theoretically, some diameter conducting electricity with the standard of A.C. system utilize today can send 85% power till 10 thousand km and 1.4 times thick wire system can send 20 thousand km, which is the length to send energy to any where from any places on the earth.The some frequency in the range of terahertz can resonate a certain molecule and induces the absorption which indicates the sort of molecule. Then the absorption spectrum easily indicate the special molecule, as an example, cancer induced or not and is enough to identify the existence of cancer, bacteria and virus and soon. And using higher power, only a special sort of molecular structure, which can be a part of cancer only absorb energy and not by other molecule can heated up only cancer and is some possibility to use as a very progressed medical treatment for the cancer and others.It is very easy to understand the possibility of science and technology for the human beings which are the very peculiar identification of the Asia.Undiagnosed chronic orofacial pain poses dilemma for dental practitioners. One of the most frequent causes of the undiagnosed orofacial pain is pain reference from surrounding structures, especially head, neck and shoulder muscles. This symposium will discuss pathophysiology of chronic orofacial pain conditions with muscle origin, their contributing factors, and management strategies. First of all, I will introduce a couple of conditions of chronic orofacial pain with masticatory and cervical muscle origin. Prof. Gracely will overview symptoms, diagnosis, and treatment of fibromyalgia. Prof Svensson will speak about mechanisms of muscle pain with his experimental data. Prof. Lavigne will show us an interaction between sleep and chronic pain and finally, Prof. Phero will address how to manage chronic orofacial pain from an anesthesiological point of view.Importance of muscle palpation is well recognized when a patient suffers from dysfunction of jaw movement and joint sounds, namely temporomandibular disorders. However, muscular problems that are not associated with jaw movement dysfunction are often overlooked, and referred jaw and tooth pain from the muscles is misdiagnosed. Patients are sometimes not aware of their muscular symptoms and routine muscle palpation following first interview discloses latent muscle problems. Some researchers point out the need of training in muscle palpation for standardizing palpating pressure that leads to a correct diagnosis. Patients with muscle pain show decreased pressure pain threshold and complain of pain reference in a distant tissue during appropriate muscle palpation. Referred jaw pain originating from masticatory muscles is differentially diagnosed by applying myofascial trigger point injections in these muscles. Jaw and tooth pain sometimes originates from cervical but not masticatory muscles. When pain is referred from deep cervical muscles, it is difficult to identify the origin of the pain with palpating muscles or applying myofascial trigger point injections. It is because muscle strain is usually observed in some cervical and shoulder muscles at once including superficial as well as deep muscles. Deep cervical plexus block anesthetizes a wide area of cervical innervations and it blocks noxious inputs from these muscles. Thus, deep cervical plexus block is used instead of myofascial trigger point injections for diagnosis of orofacial pain originating from deep cervical structures, especially muscles.This symposium will give us an insight into a mechanism of hyperexcitability and neuronal plasticity of the brainstem as well as peripheral pathology in chronic masticatory and cervical muscular pain. Referred orofacial pain from deep cervical structures and experimental data in TMD and healthy subjects represent a hypothesis of a chronic orofacial pain mechanism that is based on the neuronal convergence and central sensitization of secondary neuron in the brainstem/upper cervical spine. We will also learn about the role of the higher central nervous system through interaction between pain and sleep, affection, and balance of the autonomic nervous system. Contributing factors to the muscular pain are inappropriate posture, parafunctions of the jaws and the neck, and jobs and hobbies that require involuntary muscle strain, etc. They are maintained in daily living and may induce chronic orofacial pain. Taking off these contributing factors is sometimes difficult and it is extremely important to educate patients according to physical and behavioral therapy with coping strategies.Pain in the orofacial region can be associated with a number of local and systemic disorders. Local disorders include myalgias, spasm, and myositis, and the well known syndrome of myofascial pain, characterized by localized hypersensitive “trigger point” sites in muscle that often result in specific patterns of referred pain and autonomic effects. These trigger points are diagnosed by manual palpation, and treatment regimens include education, physical therapy, aerobic exercise, pharmacotherapy, passive stretching exercise and trigger point injections. Pain in the temporomandibular joint may be due to pathology in the joint, in adjacent muscle, or in both. Eliav, et al., have used the effects of joint inflammation on nerves in passage to devise a simple differential diagnostic test. This test uses electrical stimuli to specifically stimulate the axons of large diameter mechanoreceptors. Inflammation has been shown to increase the sensitivity in these fibers, which results in lowered electrical detection thresholds. The validity of this test has been demonstrated in an acute oral surgery model and is supported by the results of a study that showed a significant difference in electrical detection thresholds between patients with confirmed arthralgias or myalgias that normalized after joint lavage. Fibromyalgia is a systemic disorder characterized by both widespread pain and by tenderness at 18 specific sites termed “tender points.” Although superficially similar to myofascial trigger points, emerging results suggest that tenderness in fibromyalgia is not confined to these points but is present at all locations including non-muscular sites. In addition, increased pain sensitivity is not limited to pressure but is found also for heat and other forms of painful and even non stimulation. These results suggest critical differences between these syndromes. However, orofacial myofascial pain and fibromyalgia are often comorbid and recent studies of orofacial pain by Maixner and colleagues have found increased sensitivity to both pressure and to other painful modalities such as heat and tourniquet ischemia. In an ongoing longitudinal study, this group found that pain sensitivity and blood pressure were risk factors for the development of temporomandibular joint disorders (TMJD). These results strongly suggest a genetic predisposition. Further studies by Diatchenko and coworkers have examined the gene that codes for COMT, an enzyme that metabolizes catecholamines and is implicated in human pain syndromes. These investigators have identified three primary COMT haplotypes that are associated with pain sensitivity and the risk of developing temporomanibular disorders. They have shown that polymorphisms in this gene are associated with human pain sensitivity and the risk of TMJD onset. Specifically the genetic variants that result in low levels of COMT activity are associated with both increase in pain sensitivity and risk of TMJD onset. This is one of several genetic factors that may influence the onset and persistence of pain associated with fibromyalgia and TMJD. In addition, the comorbid nature of these two disorders may in part result from shared genetic variables that influence pain sensitivity, neurological function, and psychological status.Introduction. Management of complex, chronic, musculoskeletal, orofacial pain requires careful, scientific evaluation and diagnosis of each patient. Use of standardized assessment tools and accepted diagnostic terms provides accuracy in diagnosis. Correct diagnosis permits coordination of a management program that may incorporate medication and nerve block therapy to inactivate the involved nociceptive pathways. With the multitude of management options currently available, the practitioner must use caution to see that the patient's therapy is as conservative as possible.Pharmacology and Pharmacotherapy Modalities. Non-opioids. The non-opioids include the nonsteroidal anti-inflammatory drugs (NSAIDs) including COX-2 agents, acetaminophen (APAP) and tramadol. NASIDs demonstrate good analgesic efficacy for mild to moderate orofacial pain NSAIDs are recommended for the initial management of orofacial pain with an inflammatory component and musculoskeletal pain. Acetaminophen and tramadol are options that can be considered in place of or in addition to NSAID therapy.Opioids. Opioid analgesics remain the standard for treatment of severe or unremitting pain. Prescribing concerns related to abuse potential, adverse effects, tolerance, and dependence have now been addressed. Opioid therapy in musculoskeletal pain related to cancer is less laden by social, legal and professional taboos, as opioids may be the primary means of relief in this situation. Individual opioids vary in potency and degree of adverse effects. Their mechanism of action involves binding to opioid receptors, either centrally or peripherally. Opioids with long duration of action may be used for management of baseline pain with fast onset opioids used for breakthrough pain. Fixed dosing to maintain drug steady state level and discourage PRN (pro re nata “as needed”) dosing is commonly employed. Opioids have no ceiling, so dosing may be increased as needed or until side-effects are not tolerated.Other routes of opioid administration include trans-dermal absorption, iontophoresis, subcutaneous infusion, intravenous infusion, and epidural infusion to maintain opioid steady state and/or permit rapid onset for breakthrough pain.The use of mixed agonist-antagonist agents (butorphanol, nalbuphine, pentazocine) are not commonly used unless the patient is opioid naïve and avoiding spasm of the sphincter of Oddi is necessary.Psychotropic agents. Many of the agents used to manage pain overlap with those used to treat psychiatric disorders. Pain commonly consists of both nociceptive and non-nociceptive features, so the addition of these agents serves to provide a better quality of pain relief. Additionally, psychotropic agents may be used to for treatment of the pain itself or for management of the associated mood disorder.Additional pharmacotherapy agents. Membrane stabilizers, muscle relaxants, and mexiletine may be considered as therapy dependent on diagnosis.Therapeutic Interventions. The anesthesiologist has a wide spectrum of therapeutic interventions which may be used for pain diagnosis and management. Differential/diagnostic nerve blocks, injection to muscle myoneural junctions (“trigger points”), therapeutic nerve blocks, and neurolytic/neuroablative procedures may all prove useful in chronic, musculoskeletal pain diagnosis and management.Specific injection and nerve blocks include:Acupuncture. Patients with musculoskeletal orofacial pain frequently seek alternative forms of therapy. Often, these patients have experienced troublesome side effects of the medical treatment. Acupuncture is frequently used for patients with this condition.Stimulation-produced analgesia. Transcutaneous electrical nerve stimulation (TENS) has been a useful adjunct along with physical therapy to management musculoskeletal orofacial pain.Summary. The treatment of pain is now moving from symptomatic management to mechanism-based, targeted therapy along both neural and humoral pathways. With the latter approach, it is possible for clinicians to better alleviate pain and reduce central sensitization.Pain is reported by 11% to 29% of the adult population, with close to 8% of the population reporting orofacial pain. Interestingly, two out of three patients with chronic pain report a sensation of un-refreshing sleep upon awakening. The long-term consequences of sleep disruption include mood alterations, the risk of transportation or work accident, etc.The brain is partially isolated from external influences during sleep in order to preserve sleep continuity. During sleep, every 20–60 seconds the brain will take a “look” at the outside world to re-adjust body position, heart and respiratory rates. This is recognizable on sleep electrographic recordings by transient brain and heart activations which are called “sleep arousals”. The literature suggests that thalamo-cortical circuits are partially isolated from the brainstem reticular ascending neuronal network. Therefore, a sleeping brain is filtering information and will trigger an arousal if it perceives a threat. Experimental studies show that the brain can evoke a clear brain awakening across all sleep stages if pain inputs persist for a sufficient time during sleep (Lavigne et al, Pain 2004).The loss of sleep continuity by pain intrusions may contribute to mood alteration and pain exacerbation over time. It has been demonstrated in normal subjects that if they only get four hours of sleep, instead of eight, bodily pain sensations and mood alterations will develop within 3–4 days (Haack and Mullington, Pain, 2005). Loss of REM sleep is also associated with pain exacerbation and hyperalgesia on the following day (Smith et al, Sleep 2005; Roehrs et al, Sleep 2006).In chronic pain patients, these interactions need to take into account other factors that can play a role, such as anxiety, a lack of muscle fitness, medications that alter cognitive function, persistent fatigue, etc. Moreover, the presence of insomnia (delays falling asleep or long periods of wakefulness at night, respiratory disturbances (snoring, upper airway resistance, apnea), or periodic limb movements during sleep need to be considered in patients with chronic pain. Such sleep disorders contribute to the poor sleep quality and interfere with sleep recovery (restorative) functions.Chronic pain patients often report, following a night of poor sleep, more intense pain on the following day. A circular relationship between sleep perturbation and pain exacerbation has been suggested (Chapter by Lavigne et al in Principles and Practice of Sleep Medicine, Elsevier, 2005). Moreover, in patients suffering from low back or cervical pain and in fibromyalgia patients, an autonomic cardiac dysregulation has been observed during sleep. In these subjects, REM sleep is not associated with the reactivation of the autonomic-cardiac sympathetic dominance, expressed as a rapid rise in heart rate, which is normally seen (Okura et al, abst Sleep 2005).Between 30% and 65% of patients with sleep bruxism/tooth-grinding complain of morning headaches, a condition that is commonly caused by airway collapse (Upper airway resistance syndrome/limitation of airflow or Sleep Apnea/cessation of breathing). The cause and effect relationship between sleep respiratory disturbances and the maintenance of chronic pain remains to be demonstrated.Management strategies for the interactions between pain and sleep include: cognitivo-behavioral approaches (e.g., sleep hygiene, exercise, diet advice); physical therapy; devices to aid sleep bruxism or respiratory disorders; medications to promote sleep (e.g., hypnotics, antidepressive medications or others (e.g., gabapentin or pregabalin)). Note that opioids may contribute to sleep arousals and it is therefore preferable to avoid their use late in the evening. The role and safety of dopaminergic medication (e.g., pramipexole), which has been reported to improved pain in about 50% of severe fibromy-algia patients, needs to be assessed (Holman and Myers, Arthritis and Rheumatism, 2005).Research supported by Canadian Institutes of Health Research, FRSQ, CFI.Experimental pain research in healthy human subjects logically requires two steps: first, activation of the nociceptive pathways in a safe, reproducible and controllable manner, secondly, standardized assessment of the evoked pain responses. Such pain studies represent one of many approaches to gaining more insight into the pathophysio