الدكتور علي بن مبارك الزهراني

 

Nitrous oxide inhalation sedation is the most commonly used technique. It is an effective method of reducing fear, anxiety and pain and improving patient co-operation. The term inhalation sedation describes the induction of a state of conscious sedation by administering sub­anaesthetic concentration of gaseous anaesthetic agents. This technique is successfully employed in the provision of dental treatment for extractions (Blain and Hill, 1998) and comprehensive care.

 

Since the introduction of nitrous oxide into dentistry by Horace Wells in 1844, the drug has become in­creasingly popular for the management of dental anxi­ety. Nitrous oxide produces “relative analgesia,” a term which was defined by Langa (1976) as a chemically in­duced altered psychological state which eliminates the fear and pain of the dental experience. The term “relative analgesia” refers to the use of low concentrations of nitrous oxide with high concentrations of oxygen to produce sedation and a degree of analgesia. By using relative analgesia, patient’s fear and anxiety is replaced by a feeling of well-being and confidence (a state of euphoria). The patient remains conscious and co-operative, with the protective reflexes fully maintained. The patient also experiences a pleasant, floating, detached sensation.

 

Nu­merous studies have presented evidence regarding the safety and efficacy of nitrous oxide in reducing anxiety during dental treatment (Berger et al., 1972; Aspes, 1975; Anderson, 1980). A survey of the American Academy of Pediatric Dentistry indicated that 89% of the pediatric dentists reported use of nitrous oxide in their practices as an adjunct to behav­ior management techniques (Wil­son, 1996).

 

 

Nitrous oxide (N₂O) is a colorless and virtually odorless gas with a faintly sweet smell. Nitrous oxide is slightly heavier than air, with a specific gravity of 1.53, and has a blood: gas partition coefficient of 0.47. Be­cause of its low solubility in blood, it has a very rapid onset and recovery time. On inhalation of N₂O to the lungs, it has a rapid uptake as it is quickly absorbed from the alveoli and is held in a simple solution in the serum. Nitrous oxide will become saturated in blood within 3 to 5 minutes following administration. The alveolar concentration of N₂O rapidly approaches the inspired concentration. As N₂O is relatively insoluble, it passes down a gradient into other tissues and cells in the body, such as the central nervous system (CNS). The concentration of N₂O required to produce sedation will vary among individuals.

 

A phenomenon termed diffusion hypoxia may occur as the sedation is reversed at the termination of the procedure. The nitrous oxide escapes into the alveoli with such rapidity that the oxygen present becomes diluted; thus, the oxygen-carbon dioxide exchange is disrupted and a period of hypoxia is created. However, this phenomenon is reported not to occur in healthy pediatric patients (Dunn­-Russell et al., 1993). Nonetheless, to minimize this effect, the patient should be oxygenated for 5 min­utes after a sedation procedure.

 

Because of its physical properties, nitrous oxide will create pressure increase in air-filled body cav­ities. This is especially to be noted in the middle ear. Consequently, the use of nitrous oxide should be avoided in patients with active otitis media.

 

Nitrous oxide is rapidly excreted from the lungs. Once N₂O is no longer being inhaled, N₂O within the CNS will rapidly pass down the gradient into the bloodstream and out of the body via the lungs. A very small amount is excreted in body fluids (Dock and Creedon, 2004).

 

Nitrous oxide produces nonspecific central nervous system (CNS) depres­sion. Although it is classed with inhalational gen­eral anesthetics, it also produces some analgesia. Nitrous oxide is the weakest of all inhalation agents, with a minimum alveolar concentration (MAC) of 105. The MAC of an inhalation agent is a measure of its potency. It is the concentration required to produce immobility in 50% of patients. At concentrations between 30% and 50%, nitrous oxide will produce a relaxed, somnolent patient who may appear dis­sociated and easily susceptible to suggestions. Amnesia may occur in some patients, but there is little alteration of learning or memory. At concentrations greater than 60%, patients may experience dis-coordination, ataxia, giddiness, and increased sleepi­ness. It is not recommended that concentrations greater than 50% be used in dental practice (Dock and Creedon, 2004).

 

Nitrous oxide reduces hypoxic-driven ventilation and by itself will slightly increase the respiratory minute volume. As the patient becomes more re­laxed from the effects of nitrous oxide, the respira­tory rate may decrease slightly. It is non-irritating to the respiratory tract and can be given to patients with asthma without fear of bronchospasm. Prob­lems can arise, however, from the added r

Bjork^{33, 34} implanted pins in the jaws of children for longitudinal cephalometric studies and reported that those in the path of erupting teeth were displaced and those placed in resorptive areas were lost. Pins placed in areas of appositional bone growth became embedded.

 Thilander et al³⁵ concluded that osseointegrated implants in pigs remained stable in space and either became buried in alveolar bone, creating a deviation of the erupting adjacent teeth, or were lost because of bone resorption.

Ledermann et al³² in their 7-year follow-up with a mean length of 35.5 months, reported a 90% success rate on 42 endosseous dental implants placed in 34 patients aged 9 to 18 years. There was a positive soft and osseous tissue reaction to the implants, and most of the failures occurred because of subsequent traumatic injuries sustained during the healing phase after implant placement. The major complication reported was the failure of dental implants to respond to the vertical growth of adjacent teeth and alveolus due to ankylosis.

According to Smith et al,³⁶ implant use in children with ectodermal dysplasia is a treatment of choice since its placement in the mandibular anterior region of a 5-year-old patient did not affect adjacent tooth buds. Prosthesis remodeling was performed due to implant submergence.

Brugnolo et al³⁷ noted the infraclusion of implants placed in patients aged 13 to 14.5 years, secondary to vertical growth, and prosthesis was redesigned. Anteroposterior and transverse growth seemed not to negatively influence the implant’s position.

Guckes et al³⁸ described a case of a 3-year-old patient with ectodermal dysplasia in which dental implants located in the mandible and maxilla have not moved despite growth. During the 5-year follow-up, the prosthesis was remodeled to accommodate eruption of the maxillary teeth and facial growth.

 

The benefits of implant use in growing patients are as important as the concerns