.................... ARTICLE
...............................................
Julius C. Willette, DDS
Lipchewing: another treatment option This article describes a new removable appliance that has been used s u c c e ~ f i h 'to treat liwhewlng in a severely disabled, mentally retarded patient.
S
elf-injurious behavior (SIB) in the form of lip-chewing is a common occurrence among developmentally disabled patients.1-16 It has been reported in patients who have cerebral palsy, autism, epilepsy, and mental retardati~n.'-~ Among severely and profoundly retarded individuals, the prevalence of some form of SIB approaches 40%.4 The most dramatic of these is LeschNyhan syndrome, an x-linked genetic disorder of purine metabolism. These patients take lip-chewing to the extreme, often resulting in mutilation or amputation of lips along with the tongue and finger^.^-^ Others who engage in lip-chewing include decerebrate or comatose patients and patients who have a sensory neuropathy, such as congenital insensitivity to ~ain.~-'O
Etiology Lip-chewing may have multiple causes with both organic and behavioral components. In Lesch-Nyhan syndrome, lip-chewing is one of the diagnostic signs. A mutilated lip in the primary-dentition stage of development may be the phenotypic expression of the basic genetic defect, mediated somehow through centralacting neurotran~rnitters."-'~ One theory of causation postulates that SIB occurs as a mechanism for intrinsic reward. The individual engages in SIB in order to gain endogenous release of beta-endorphin, which functions as a brain opiate in reducing the pain of injury, while producing e~phoria.'~,'~ In patients who are comatose or lack a cerebrum, lip-chewing has been described as an involuntary behavior.
174 Special Care In Dentistry, Vol12 No 4 1992
The presence of the lower lip between the teeth acts as a bolus of food, triggering reflex arcs in the pons that set cyclic jaw movements in moti0n.233~14 Involuntary lip-chewing may occur in patients with cerebral palsy because of faulty nerve-muscle function.l0 In epilepsy, patients often chew or bite lips during seizure. Gedye has reported that much SIB of a severe nature among mentally retarded patients may be due to frontal lobe seizure activity, and that this behavior is really invol~ntary.'~ It is important to remember that the episodic SIB seen in patients with CP or epilepsy is quite different from that seen in comatose patients or in those with Lesch-Nyhan syndrome. In the former, injuries are constant and less severe and do not require a preventive appliance. In the latter, severe tissue damage is often the rule, and professional intervention is critical. Behaviorists think that severe SIB may have more than one etiology, and there are many behavioral theories. One theory holds that self-injury is maintained by the positive consequences that follow. Some behavioral researchers believe that SIB is a more extreme form of stereotypy in which the individual attempts to maintain homeostasis or to escape from internal or external stress. Among mentally retarded patients, SIB may be a powerful means of gaining personal attention from care-giver~."'~,~~
Report of case The patient, a 24-year-old male with pronounced macrocephaly, presented at the dental clinic of Fircrest School, a Washington State
Department of Social and Health Services facility located in Seattle. He was referred to the clinic by nursing staff who were concerned about possible aspiration of blood from bleeding of the lower lip due to chewing. A review of his medical history revealed that his profound mental retardation had been associated with hydrocephalus and post-natal cerebral infection. A five-year-old CAT scan showed severe hydrocephalus with no recognizable cortical mantle. He was cortically blind, had no speech, and was hearing-impaired. He had scoliosis secondary to spasticity from CNS damage and extremely severe spastic quadriplegia with severe contractures of all major joints. He had a history of GI bleeding, aspiration pneumonias, recurrent otitis media, and eye infections. He received gastrostomy tube feedings. He had been institutionalized since age two and was characterized by his physician as "medically fragile". Dental history was obtained by telephone from previous dentists and by parent interview. Lip-chewing had been a lifetime behavior with periodic severe exacerbations. His maxillary canines had been extracted years earlier, but this did not prevent further SIB. Subsequent treatment by another dentist involved the wiring of a silicone lip-bumper appliance to the mandibular arch. This had been effective for a short while, but could remain in place for only a few weeks at a time before resulting in periodontal damage. Extra-oral exam was negative for signs of pathology. Intra-oral exam was difficult. The patient was chewing his lower lip and moaning. The lip was positioned between the maxillary and mandibular incisors. The patient had a primitive bite reflex, and use of a mouth prop produced forceful and tenacious clenching. Lingual stimulation resulted in gagging. The patient had a complete adult dentition except for the maxillary canines which had been extracted. Heavy attrition from bruxism was apparent in a flat occlusal plane, with reduced vertical dimension of all posterior clinical crowns. He had
chronic marginal gingivitis. There was a 4-5-mm area of gingival recession on the labial side of the mandibular canines. This recession appeared to be secondary to irritation caused by movement of the lip-bumper. The lower lip showed evidence of chronic trauma. Ulceration over sloughing necrosis and scar tissue covered most of the mucosal surface.
Treatment Treatment for self-inflicted lip injury varies with the individual case. Behavioral approaches, drug therapy, and oral appliances, or combinations of these, have been the recommended Behavioral approaches are based on the premise that SIB is in some way rewarding.4J7JsTechniques for treatment include: differential reinforcement of non-SIB; removal of positive consequences of SIB: punishment of SIB; and combinations of these and other techniques.1 3 4 11,15,20 Drug therapy is sometimes used alone, but more often as an adjunct to behavioral programs. Many oral appliances has been reported that prevent lip injury and allow for wound healing.2 3 9 10,16 In spite of these therapies, severe, chronic lip-chewing in severely and profoundly retarded patients has been very difficult to reduce or eliminate.1,34,1720 The lip shield which was designed for this patient was aimed at separating the lips and cheeks from the teeth in order to allow for healing. This shield was only part of the treatment. Drug therapy as well as behavior managment methods were being used concurrently. A removable thermoplastic lip shield was fabricated from polycapralactone (Aquaplast-T),a material that was reported in the dental literature by Leinbach to be physiologically sound for construction of mouthstick appliancesF1 Aquaplast-T comes in flat sheets 1/8 inch thick. It will not break when dropped. It can be scored with a laboratory knife and then broken along the scored line when at room temperature. When heated in a water bath to 140"F, it turns from opaque to clear and can be fingermolded to the desired shape. WorkI
ing time is from two to three minutes before it hardens, but it can be reheated and reshaped repeatedly. We produced the appliance pictured in Fig. 1chairside by beginning with the approximate shape and size of the facial aspect of medium-sized alginate impression trays as a guide. Customfitting was done in the mouth. Border trimming was done with scissors while the material was clear-colored, and a handle was attached for ease of insertion and removal. Aquaplast-T adheres to itself when heated until clear. Air holes were cut with a round acrylic laboratory bur to allow for mouth breathing, but this patient consistently breathed through his nose. The borders were then lined with Lynal@tissue conditioner to accommodate the delicate alveolar mucosa at the depth of the vestibule. Care was taken in this regard to provide just enough extension for retention, without the overextension that would result in tissue trauma. Extension was determined intraorally, with the patient in centric occlusion. Retention depended upon the size and shape of the shield and the fact that the patient was quadriplegic and could not remove it by himself. Fig. 2 shows the lip shield in place.
Fig 1. Llp shield fabrlcated at chairside.
Fig 2. Lip shield In use.
Special Care In Dentistry, Vol12 No 4 1992 171
The nursing staff was trained in insertion, monitoring, and care and maintenance, and orders were written for PRN use. Initially, the shield was tried on a 24-hour basis, but after 20 hours, the patient became visibly agitated, turning red in the face with perspiration on his forehead, and the shield was removed. This immediately relieved the symptom of distress. A second attempt was made to use the shield full-time, but on this occasion, the patient displayed similar symptoms and, after several hours, began to make gagging noises. The shield was again removed. He tolerated the shield better when given a small amount of sedation, but would then sleep for most of the day. The protocol which was finally arrived at called for strict PRN use following lipchewing. After six weeks of carefully monitored PRN use, the lip had healed, leaving only scar tissue as evidence of a lifetime of lip-chewing trauma.
Discussion Often in dentistry for special populations, the dentist is faced with situations that seem to be unique and call for creative problem-solving. This was such a case. The patient’s primitive bite reflex and hypersensitive gag reflex prohibited use of removable appliances that relied on teeth for retention. Fixed appliances would require sedation or hospitalization for one or more sessions of general anesthesia. The medical risk for this patient was too high for this because of his fragile condition. The lip shield was easy to produce and provided a quick and effective temporary solution. Unfortunately, the lip shield did not cure the patient of lip-chewing. It is used on an asneeded basis to prevent injury and control bleeding whenever lipchewing begins, and to allow for subsequent healing. But this patient’s SIB is chronic and cyclic in nature and ranges in severity from minor “nib-
bling’’ on the mucosa to deep and extensive wounds. It is important to remember that this was a predictable outcome, because any preventive appliance used in this way is a medical restraint. Medical restraints, in cases of this kind, have been shown to suppress SIB, but when they are removed, the SIB return^.^ It is also important to note that, as Gedye and others have pointed out, the injurious behavior seen in this patient is probably involuntary and would not be eliminated through the usual behavior modification or medication metho d ~ . ~Ultimately, ~,*~ this patient’s best option is probably removal of lower anterior teeth in order to break the neuropathologic chewing cycle. The lip shield has limited application. It requires careful monitoring, because it could lead to soft-tissue damage or even contribute to aspiration in case of vomiting. Since many tube-fed patients have an esophageal reflux problem, this appliance should be used with extreme caution and constant monitoring. One serious vomiting episode could be lifethreatening. It cannot be used with ambulatory patients or those who might be inclined to remove it themselves. Dr. Willette is a part-time faculty member at the University of Washington School of Dentistry, a faculty member of the DECOD Graduate Training Program at the University of Washington, and Dental Director of the Fircrest School in Seattle, 15230 15th Ave., NE, Seattle, WA 98155. Correspondence may be addressed to him at the Fircrest School.
1. Dura JR, Torsell AE, Heinzerling RA, Mulick JA. Special oral concerns in people with severe and profound mental retardation. Spec Care Dent 6:265-7,1988. 2. Fenton SJ. Management of oral selfmutilation in neurologically impaired children. Spec Care Dent 2:70-3,1982. 3. Turley PK, Henson JL. Self-injurious lipbiting: etiology and management. J Pedodont 7:209-20,1983. 4. Rubin IL, Crocker AC. Developmental disabilities: delivery of medical care for children and adults. Philadelphia (PA): Lea
176 Special Care in Dentistry, Vol12 No 4 1992
& Febiger, 354-60,1989. 5. Cudzinowski L, Perreault JG. The LeschNyhan Syndrome: report of a case. J Dent Child 46:143-4,1979. 6. Dicks JL. Lesch-Nyhan Syndrome: a treatment planning dilemma. Fed Dentist 4127-30,1982. 7. LaBanc J, Epker BN. Resch-Nyhan Syndrome: Surgical treatment in a case with lip chewing. J Maxillofac Surg 964-7, 1981. 8. Little JW. Oral manifestations of the congenital insensitivity-to-pain syndrome. Oral Surg 50.220-5,1980. 9. Croglio DP, Thines TJ, Fleischer MS, Anders PL. Self-inflictedoral trauma: report of case. Spec Care Dent 9:5&61,1990. 10. Sonnenberg EM. Treatment of self-induced trauma in a patient with cerebral palsy. Spec Care Dent 1089-90,1990. 11. Cataldo MF, Harris J. The biological basis for self-injury in the mentally retarded. Anal Intervent Developmental Disabil 2:21-39,1982. 12. Lesch M. Nyhan WL. A familial disorder of uric acid metabolism and central nervous system function. Am J Med 36:561-70,1964. 13. Nyhan WL, Johnson HG, Kaufman IA, Jones KL. Serotonergic approaches to the modification of behavior in the LeschNyhan Syndrome. Appl Res Ment Retardation 1:25-40,1980. 14. Guyton AC. Textbook of medical physiology. 7th ed.Philadelphia (PA): Saunders, 759-60,1986. 15. Heidron SD, Jensen CJ. Generalization and maintenance of the reduction of selfinjurious behavior maintained by two types of reinforcement. Behav Res Ther 22~581-6,1984. 16. Dawson LR, Hoffman JA. Treatment of a traumatic ulcer on a handicapped individual: a case report. Spec Care Dent 2207-8,1982. 17. Sandman CA, Datta PC, Barron J, Joejler FK,Williams C, Swanson JM. Naloxone attenuates self-abusive behavior in developmentally disabled clients. Appl Res Ment Retardation 4:5-11,1983. 18. Barrett RP,Feinstein C, Hole WT. Effects of naloxone and naltrexone on self-injury: a double-blind placebo-controlled analysis. Am J Ment Retardation 93:644-51,1989. 19. Gedye A. Extreme self-injury attributed to frontal lobe seizures. Am J Ment Retardation 1:20-6,1989. 20. Linscheid TR, Iwata BA, Ricketts RW, Williams DE, Griffin JC. Clinical evaluation of the self-injurious behavior inhibiting system (SIBIS).J Appl Behav Anal 23:53-78,1990. 21. Leinbach TE. A thermoplastic mouthstick appliance. Spec Care Dent 7221-3,1987.
...............................................
Julius C. Willette, DDS
Lipchewing: another treatment option This article describes a new removable appliance that has been used s u c c e ~ f i h 'to treat liwhewlng in a severely disabled, mentally retarded patient.
S
elf-injurious behavior (SIB) in the form of lip-chewing is a common occurrence among developmentally disabled patients.1-16 It has been reported in patients who have cerebral palsy, autism, epilepsy, and mental retardati~n.'-~ Among severely and profoundly retarded individuals, the prevalence of some form of SIB approaches 40%.4 The most dramatic of these is LeschNyhan syndrome, an x-linked genetic disorder of purine metabolism. These patients take lip-chewing to the extreme, often resulting in mutilation or amputation of lips along with the tongue and finger^.^-^ Others who engage in lip-chewing include decerebrate or comatose patients and patients who have a sensory neuropathy, such as congenital insensitivity to ~ain.~-'O
Etiology Lip-chewing may have multiple causes with both organic and behavioral components. In Lesch-Nyhan syndrome, lip-chewing is one of the diagnostic signs. A mutilated lip in the primary-dentition stage of development may be the phenotypic expression of the basic genetic defect, mediated somehow through centralacting neurotran~rnitters."-'~ One theory of causation postulates that SIB occurs as a mechanism for intrinsic reward. The individual engages in SIB in order to gain endogenous release of beta-endorphin, which functions as a brain opiate in reducing the pain of injury, while producing e~phoria.'~,'~ In patients who are comatose or lack a cerebrum, lip-chewing has been described as an involuntary behavior.
174 Special Care In Dentistry, Vol12 No 4 1992
The presence of the lower lip between the teeth acts as a bolus of food, triggering reflex arcs in the pons that set cyclic jaw movements in moti0n.233~14 Involuntary lip-chewing may occur in patients with cerebral palsy because of faulty nerve-muscle function.l0 In epilepsy, patients often chew or bite lips during seizure. Gedye has reported that much SIB of a severe nature among mentally retarded patients may be due to frontal lobe seizure activity, and that this behavior is really invol~ntary.'~ It is important to remember that the episodic SIB seen in patients with CP or epilepsy is quite different from that seen in comatose patients or in those with Lesch-Nyhan syndrome. In the former, injuries are constant and less severe and do not require a preventive appliance. In the latter, severe tissue damage is often the rule, and professional intervention is critical. Behaviorists think that severe SIB may have more than one etiology, and there are many behavioral theories. One theory holds that self-injury is maintained by the positive consequences that follow. Some behavioral researchers believe that SIB is a more extreme form of stereotypy in which the individual attempts to maintain homeostasis or to escape from internal or external stress. Among mentally retarded patients, SIB may be a powerful means of gaining personal attention from care-giver~."'~,~~
Report of case The patient, a 24-year-old male with pronounced macrocephaly, presented at the dental clinic of Fircrest School, a Washington State
Department of Social and Health Services facility located in Seattle. He was referred to the clinic by nursing staff who were concerned about possible aspiration of blood from bleeding of the lower lip due to chewing. A review of his medical history revealed that his profound mental retardation had been associated with hydrocephalus and post-natal cerebral infection. A five-year-old CAT scan showed severe hydrocephalus with no recognizable cortical mantle. He was cortically blind, had no speech, and was hearing-impaired. He had scoliosis secondary to spasticity from CNS damage and extremely severe spastic quadriplegia with severe contractures of all major joints. He had a history of GI bleeding, aspiration pneumonias, recurrent otitis media, and eye infections. He received gastrostomy tube feedings. He had been institutionalized since age two and was characterized by his physician as "medically fragile". Dental history was obtained by telephone from previous dentists and by parent interview. Lip-chewing had been a lifetime behavior with periodic severe exacerbations. His maxillary canines had been extracted years earlier, but this did not prevent further SIB. Subsequent treatment by another dentist involved the wiring of a silicone lip-bumper appliance to the mandibular arch. This had been effective for a short while, but could remain in place for only a few weeks at a time before resulting in periodontal damage. Extra-oral exam was negative for signs of pathology. Intra-oral exam was difficult. The patient was chewing his lower lip and moaning. The lip was positioned between the maxillary and mandibular incisors. The patient had a primitive bite reflex, and use of a mouth prop produced forceful and tenacious clenching. Lingual stimulation resulted in gagging. The patient had a complete adult dentition except for the maxillary canines which had been extracted. Heavy attrition from bruxism was apparent in a flat occlusal plane, with reduced vertical dimension of all posterior clinical crowns. He had
chronic marginal gingivitis. There was a 4-5-mm area of gingival recession on the labial side of the mandibular canines. This recession appeared to be secondary to irritation caused by movement of the lip-bumper. The lower lip showed evidence of chronic trauma. Ulceration over sloughing necrosis and scar tissue covered most of the mucosal surface.
Treatment Treatment for self-inflicted lip injury varies with the individual case. Behavioral approaches, drug therapy, and oral appliances, or combinations of these, have been the recommended Behavioral approaches are based on the premise that SIB is in some way rewarding.4J7JsTechniques for treatment include: differential reinforcement of non-SIB; removal of positive consequences of SIB: punishment of SIB; and combinations of these and other techniques.1 3 4 11,15,20 Drug therapy is sometimes used alone, but more often as an adjunct to behavioral programs. Many oral appliances has been reported that prevent lip injury and allow for wound healing.2 3 9 10,16 In spite of these therapies, severe, chronic lip-chewing in severely and profoundly retarded patients has been very difficult to reduce or eliminate.1,34,1720 The lip shield which was designed for this patient was aimed at separating the lips and cheeks from the teeth in order to allow for healing. This shield was only part of the treatment. Drug therapy as well as behavior managment methods were being used concurrently. A removable thermoplastic lip shield was fabricated from polycapralactone (Aquaplast-T),a material that was reported in the dental literature by Leinbach to be physiologically sound for construction of mouthstick appliancesF1 Aquaplast-T comes in flat sheets 1/8 inch thick. It will not break when dropped. It can be scored with a laboratory knife and then broken along the scored line when at room temperature. When heated in a water bath to 140"F, it turns from opaque to clear and can be fingermolded to the desired shape. WorkI
ing time is from two to three minutes before it hardens, but it can be reheated and reshaped repeatedly. We produced the appliance pictured in Fig. 1chairside by beginning with the approximate shape and size of the facial aspect of medium-sized alginate impression trays as a guide. Customfitting was done in the mouth. Border trimming was done with scissors while the material was clear-colored, and a handle was attached for ease of insertion and removal. Aquaplast-T adheres to itself when heated until clear. Air holes were cut with a round acrylic laboratory bur to allow for mouth breathing, but this patient consistently breathed through his nose. The borders were then lined with Lynal@tissue conditioner to accommodate the delicate alveolar mucosa at the depth of the vestibule. Care was taken in this regard to provide just enough extension for retention, without the overextension that would result in tissue trauma. Extension was determined intraorally, with the patient in centric occlusion. Retention depended upon the size and shape of the shield and the fact that the patient was quadriplegic and could not remove it by himself. Fig. 2 shows the lip shield in place.
Fig 1. Llp shield fabrlcated at chairside.
Fig 2. Lip shield In use.
Special Care In Dentistry, Vol12 No 4 1992 171
The nursing staff was trained in insertion, monitoring, and care and maintenance, and orders were written for PRN use. Initially, the shield was tried on a 24-hour basis, but after 20 hours, the patient became visibly agitated, turning red in the face with perspiration on his forehead, and the shield was removed. This immediately relieved the symptom of distress. A second attempt was made to use the shield full-time, but on this occasion, the patient displayed similar symptoms and, after several hours, began to make gagging noises. The shield was again removed. He tolerated the shield better when given a small amount of sedation, but would then sleep for most of the day. The protocol which was finally arrived at called for strict PRN use following lipchewing. After six weeks of carefully monitored PRN use, the lip had healed, leaving only scar tissue as evidence of a lifetime of lip-chewing trauma.
Discussion Often in dentistry for special populations, the dentist is faced with situations that seem to be unique and call for creative problem-solving. This was such a case. The patient’s primitive bite reflex and hypersensitive gag reflex prohibited use of removable appliances that relied on teeth for retention. Fixed appliances would require sedation or hospitalization for one or more sessions of general anesthesia. The medical risk for this patient was too high for this because of his fragile condition. The lip shield was easy to produce and provided a quick and effective temporary solution. Unfortunately, the lip shield did not cure the patient of lip-chewing. It is used on an asneeded basis to prevent injury and control bleeding whenever lipchewing begins, and to allow for subsequent healing. But this patient’s SIB is chronic and cyclic in nature and ranges in severity from minor “nib-
bling’’ on the mucosa to deep and extensive wounds. It is important to remember that this was a predictable outcome, because any preventive appliance used in this way is a medical restraint. Medical restraints, in cases of this kind, have been shown to suppress SIB, but when they are removed, the SIB return^.^ It is also important to note that, as Gedye and others have pointed out, the injurious behavior seen in this patient is probably involuntary and would not be eliminated through the usual behavior modification or medication metho d ~ . ~Ultimately, ~,*~ this patient’s best option is probably removal of lower anterior teeth in order to break the neuropathologic chewing cycle. The lip shield has limited application. It requires careful monitoring, because it could lead to soft-tissue damage or even contribute to aspiration in case of vomiting. Since many tube-fed patients have an esophageal reflux problem, this appliance should be used with extreme caution and constant monitoring. One serious vomiting episode could be lifethreatening. It cannot be used with ambulatory patients or those who might be inclined to remove it themselves. Dr. Willette is a part-time faculty member at the University of Washington School of Dentistry, a faculty member of the DECOD Graduate Training Program at the University of Washington, and Dental Director of the Fircrest School in Seattle, 15230 15th Ave., NE, Seattle, WA 98155. Correspondence may be addressed to him at the Fircrest School.
1. Dura JR, Torsell AE, Heinzerling RA, Mulick JA. Special oral concerns in people with severe and profound mental retardation. Spec Care Dent 6:265-7,1988. 2. Fenton SJ. Management of oral selfmutilation in neurologically impaired children. Spec Care Dent 2:70-3,1982. 3. Turley PK, Henson JL. Self-injurious lipbiting: etiology and management. J Pedodont 7:209-20,1983. 4. Rubin IL, Crocker AC. Developmental disabilities: delivery of medical care for children and adults. Philadelphia (PA): Lea
176 Special Care in Dentistry, Vol12 No 4 1992
& Febiger, 354-60,1989. 5. Cudzinowski L, Perreault JG. The LeschNyhan Syndrome: report of a case. J Dent Child 46:143-4,1979. 6. Dicks JL. Lesch-Nyhan Syndrome: a treatment planning dilemma. Fed Dentist 4127-30,1982. 7. LaBanc J, Epker BN. Resch-Nyhan Syndrome: Surgical treatment in a case with lip chewing. J Maxillofac Surg 964-7, 1981. 8. Little JW. Oral manifestations of the congenital insensitivity-to-pain syndrome. Oral Surg 50.220-5,1980. 9. Croglio DP, Thines TJ, Fleischer MS, Anders PL. Self-inflictedoral trauma: report of case. Spec Care Dent 9:5&61,1990. 10. Sonnenberg EM. Treatment of self-induced trauma in a patient with cerebral palsy. Spec Care Dent 1089-90,1990. 11. Cataldo MF, Harris J. The biological basis for self-injury in the mentally retarded. Anal Intervent Developmental Disabil 2:21-39,1982. 12. Lesch M. Nyhan WL. A familial disorder of uric acid metabolism and central nervous system function. Am J Med 36:561-70,1964. 13. Nyhan WL, Johnson HG, Kaufman IA, Jones KL. Serotonergic approaches to the modification of behavior in the LeschNyhan Syndrome. Appl Res Ment Retardation 1:25-40,1980. 14. Guyton AC. Textbook of medical physiology. 7th ed.Philadelphia (PA): Saunders, 759-60,1986. 15. Heidron SD, Jensen CJ. Generalization and maintenance of the reduction of selfinjurious behavior maintained by two types of reinforcement. Behav Res Ther 22~581-6,1984. 16. Dawson LR, Hoffman JA. Treatment of a traumatic ulcer on a handicapped individual: a case report. Spec Care Dent 2207-8,1982. 17. Sandman CA, Datta PC, Barron J, Joejler FK,Williams C, Swanson JM. Naloxone attenuates self-abusive behavior in developmentally disabled clients. Appl Res Ment Retardation 4:5-11,1983. 18. Barrett RP,Feinstein C, Hole WT. Effects of naloxone and naltrexone on self-injury: a double-blind placebo-controlled analysis. Am J Ment Retardation 93:644-51,1989. 19. Gedye A. Extreme self-injury attributed to frontal lobe seizures. Am J Ment Retardation 1:20-6,1989. 20. Linscheid TR, Iwata BA, Ricketts RW, Williams DE, Griffin JC. Clinical evaluation of the self-injurious behavior inhibiting system (SIBIS).J Appl Behav Anal 23:53-78,1990. 21. Leinbach TE. A thermoplastic mouthstick appliance. Spec Care Dent 7221-3,1987.
