Management of Medically Compromised Orthodontic Patients

1. Management of Medically Compromised Orthodontic Patients February 22, 2010

2. Introduction A pilot study performed in 2002 of several orthodontic practices revealed that more than 25% of patients seeking orthodontic therapy had some medical diagnosis that potentially impacted their care

3. Most common medical problems include:  Hypersensitivity reactions Adenotonsillar hypertrophy Seizure disorders Diabetes Psychiatric disorders Pediatric cancer Special needs Cardiac disorders Bleeding disorders Asthma

4. Topics to be discussed today: Hypersensitivity reactions Seizure disorders Pediatric cancer patients Cardiac disease Bleeding disorders Asthma

5. Hypersensitivity reactions Most common hypersensitivity reactions in orthodontic practice are due to the use of latex-based products and to the alloy components of metal-based orthodontic appliances Reactions of irritant origin are usually associated with direct friction between soft tissues and orthodontic appliances Hypersensitivity reactions are related to the antigenicity of some materials that results in an adverse patient response

6. Type I hypersensitivity Type I hypersensitivity to natural rubber latex represents an immediate antibody-mediated allergic response to multiple proteins on the latex product Less than 1% of the general population are reported to be diagnosed with potential type I natural rubber hypersensitivity A higher prevalence (between 6% and 12%) is reported among dental professionals

7. Patients at particular risk of allergy to natural rubber latex include: People with a history of atopy Atopy is a disease characterized by a tendency to be �hyperallergic�--A patient with atopic allergies has atopic eczema or atopic dermatitis since infancy Those who have had repeated operations and extensive contact with rubber surgical drains Those with spina bifida A history of itching and redness from contact with balloons, rubber dams, etc.

8. A typical atopic manifestation: Eczema

9. Potential Risk factors for latex allergy: Hay fever Asthma Eczema Contact dermatitis Food allergy can also point to a potential latex allergy bananas, avocado, passion fruit, kiwi, and chestnuts have proteins that are capable of cross-reacting with latex proteins These foods can thereby act as a possible mode of sensitization to the natural rubber latex materials

10. Test for Type I hypersensitivity Clinical tests, of which the skin prick test is considered the most accurate, can determine the presence of circulating antinatural rubber latex antibodies

11. Type IV hypersensitivity

12. Allergic contact dermatitis

13. Test for Type IV hypersensitivity Patch testing, which consists of a series of allergens applied to the upper back for 24 to 48 hours, is followed by a specialist examination for 1 to 7 days after the patches are removed Positive testing reveals areas of red and inflamed skin under the patches, indicative of an allergy to the applied chemical

14. Elastic Bands Elastic bands represent another potential source of latex allergy protein that must considered The extension force pattern was reported to be different for NRL (Natural Rubber Latex) and NRL-free alternatives (Silicone Bands) Silicone bands showed greater force decay than NRL elastics, and it was concluded that great improvements in the physical properties of the silicone bands would be required before they could be considered as an acceptable alternative to NRL elastics After static force extension of 450% for 1 day in saliva, the force decay was 33% for the silicone bands and 28% for the NRL elastics .

15. Latex vs Latex-Free Elastics The ideal force required to maximize the rate of tooth movement is still unknown, although most evidence would suggest that there is a wide force spectrum to which teeth will respond appropriately Although NRL-free elastics do not perform as well as NRL elastics in laboratory studies, it is unlikely that the relatively small mechanical differences in force decay would have a clinically significant effect No clinical trial has compared NRL and NRL-free elastics to date

16. Examples of NRL-free products

17. Ways to Minimize Risk Best management of natural rubber latex hypersensitivity is to avoid contact with the product and use of alternative products made of synthetic rubber or plastic Natural rubber latex gloves should be substituted with alternative ones made of other components such as nitrile, neoprene, vinyl, polyurethane, and styrene-based rubbers The use of powder-free gloves will diminish the amount of aerosolized allergens

18. Ways to Minimize Risk More frequent office cleanings Air-duct filter changes and cleanings Early morning appointments can reduce patient exposure to airborne natural rubber latex particles Administration of pretreatment antihistamines In the event of a severe type I reaction, emergency procedures such as administration of epinephrine are recommended ( i.e. EpiPen�) Use of latex free products during treatment

19. EpiPen� Epinephrine constricts blood vessels, relaxes smooth muscles in the lungs to improve breathing, stimulates the heartbeat, and works to reverse hives and swelling around the face and lips The effects of epinephrine usually last 10 to 20 minutes so immediate medical attention is still required EpiPen� auto-injector should only be used on the fleshy outer portion of the thigh and can be used through clothing

20. Metal-based allergic reactions

21. Nickel

22. Orthodontic appliances and hypersensitivity reactions: Study A study by Bass and colleagues of 29 subjects (18 female, 11 male) reported an initial positive skin patch test to nickel sulfate in five of the female patients and in none of the male patients These five subjects (who tested positive with the skin patch test) plus the negative patch-testers were followed over the course of treatment after banding and bracketing with fixed stainless steel appliances None of the positive or negative test patients evidenced inflammatory reactions or discomfort as a result of the orthodontic appliances Two of the original negative test result patients, one female and one male, converted to a positive patch test to nickel. Again, no localized allergic-type responses were noted relative to the appliances. The authors concluded that the nickel-containing appliances had no allergic effects on the oral tissues, although the appliances may play a role in inducing nickel sensitivity Seminars in OrthodonticsVolume 10, Issue 4, December 2004, Pg 240-243 The Medically Compromised Orthodontic Patient

23. Possible Cause of Hypersensitivity An in vitro corrosion study by Grimsdottir and colleagues reported that nickel release from orthodontic metal appliances is most related to the solder composition and manufacturing of the appliances rather than being directly related to the actual nickel content The study analyzed facebows, brackets, molar bands, and both stainless steel and nickel titanium arch wires for nickel release when stored in physiologic saline

24. Findings The analysis indicated that appliances using silver and gold solders (eg, facebows and molar bands) showed enhanced release of nickel and chromium In contrast, alloys containing titanium, for example arch wires, released little nickel when tested under the static conditions of this study As noted by these studies, titanium has the advantage of being highly resistant to corrosion and may bind the nickel from release in these in vitro studies What is unknown is whether friction of the archwires in brackets might enhance the release of metal components from the appliances

25. Common Clinical Findings

26. Summary Research literature suggests that metal-based orthodontic appliances do not increase the risk for nickel hypersensitivity to patients Our current knowledge of intraoral orthodontic appliance corrosion patterns and the rare occurrence of possible nickel allergic responses in patients suggests that concerns about sensitizing orthodontic patients to nickel are not supported in the literature Caution and close monitoring should be exercised in patients with a defined history of atopic dermatitis to nickel-containing metals but that orthodontic treatment avoidance is unnecessary

27. Seizure Disoders A seizure is a sudden, involuntary, time-limited alteration in neurologic function resulting from abnormal electrical discharge of cerebral neurons Seizures manifest as altered sensation, behavior, or consciousness Epilepsy is defined as two or more seizures that are not provoked and are not due to an acute disturbance of the brain It is a sign of underlying brain dysfunction, rather than a single disease There are many different types of epilepsy and treatment and prognosis varies by type

28. Etiology The cumulative incidence of epilepsy from birth through age 20 years is about 1% and increases to 3% at age 75 Epilepsy with a recognized cause is termed �secondary�; those patients for whom a cause cannot be determined have �primary� epilepsy Etiology in childhood includes congenital abnormalities, birth-related complications, trauma, meningitis, encephalitis, and malignancy Adult etiologies are brain tumors, cerebral vascular disease, head trauma, and degenerative changes

29. Seizure Disorders Seizure disorders are the most common serious chronic neurological condition Contemporary management may include medications, surgery, an implanted nerve-stimulation device, and/or a ketogenic diet

30. Ketogenic Diet Normally, our bodies run on energy from glucose, which we get from food We can't store large amounts of glucose however, and only have about a 24-hour supply The ketogenic diet is a low carbohydrate and high fat diet 80% of calories come from fat and the rest from carbs and proteins Each meal has about four times as much fat as protein or carbohydrate More effective in children (length of diet is about 2 years) It forces the child's body to burn fat round the clock by keeping calories low and making fat products the primary food that the child is getting

31. Effectiveness of the Diet About a third of children who try the ketogenic diet become seizure free, or almost seizure free Another third improve but still have some seizures The rest either do not respond at all or find it too hard to continue with the diet, either because of side effects or because they can't tolerate the food

32. Side effects of the ketogenic diet

33. Types of Seizures Seizures lasting longer than 30 minutes or rapidly recurring seizures are termed �status epilepticus� Convulsive seizures that continue longer than 10 minutes require treatment by medical professionals who can administer intravenous anticonvulsive medication and support the patient�s respirations as needed With early recognition and appropriate treatment, patients with an episode of status epilepticus should have no residual adverse effects

34. Types of Seizures Absence --10�30 sec loss of consciousness, brief eye or muscle fluttering, sudden halt in activity Tonic-clonic �loss of consciousness with falling, 10�20 sec muscle rigidity followed by 2�5 min clonic contractions of muscles of extremities, head, trunk; urinary and/or fecal incontinence, postictal deep sleep 10�30 min Atonic --Brief loss of muscle tone with falling Clonic --Alternating muscle contraction and relaxation Tonic-- persistent firm muscle contractions

35. Co-morbidity Having a seizure disorder affects almost every aspect of life Education, social life, emotional health, physical abilities, and financial resources are all impacted Cognitive impairments occur frequently; this is thought to be multifactorial with underlying brain abnormalities, effects of seizures, and medication side effects playing additive roles Patients with epilepsy have an increased prevalence of depression and anxiety compared with the general population

36. Seizure Triggers Some patients have identified triggers that impact the number and severity of seizures including: Flashing lights Anxiety Illness Hyperventilation 7 Factors reported to increase seizures include: Stress Missed medication Sleep deprivation Alcohol consumption Nonprescription medications Vitamin or mineral deficiencies Parts of the menstrual cycle

37. Orthodontic considerations Record a detailed history: specific details about seizure onset, frequency, and type, behavior during seizures, duration, triggers, recovery period, medical management, and compliance Be prepared to respond: The practitioner and staff should be prepared to respond appropriately when a patient has a seizure in the orthodontic office Gingival hypertrophy associated with anticonvulsant medication and past dental or facial trauma should be considered when planning treatment and reviewed as part of patient informed consent

38. MRI Scans Often, the patient�s physician requests the removal of appliances for an MRI scan The metal in a fixed orthodontic appliance may distort images obtained by the MRI In some patients, an MRI may be obtained if archwires are removed before the scan Oftentimes, though, the removal of the entire orthodontic appliances is required

39. Seizures and Dental Care There is little in the dental literature regarding the implications of seizure disorders on oral health and delivery of dental care Dentofacial trauma occurring during seizures has been reported to include injuries to the tongue, buccal mucosa, facial fractures, avulsion, luxation or fractures of teeth, and subluxation of the temporomandibular joint

40. Dental Side Effects Gingival Hyperplasia reported to occur in up to 50% of patients treated with phenytoin (Dilantin), sodium valproate (Depakote), and ethosuximide (Emeside and Zarontin) Other side effects of medications recurrent aphthous-like ulcerations, gingival bleeding, hypercementosis, root shortening, anomalous tooth development, delayed eruption, and cervical lymphadenopathy Asymmetry Of particular interest to the orthodontist is a recent report of facial and body asymmetries affecting 41% of patients with partial seizures in the population studied; asymmetries included both hemihypertrophy and atrophy

41. Study of Asymmetries in Epileptic Patients Clinically differentiating between localized related epilepsy and generalized epilepsy is important because it carries significant implications for planning diagnostic management strategy Body asymmetry was found in 88 out of 282 cases, in which 64 (73.5%) suffered from localization related epilepsy. Among localization related epilepsy, asymmetries were found in 41.5% of patients In contrast, only 18.75% of patients with generalized seizure disorders showed similar findings

42. Epilepsy and Asymmetry Study validates the importance of clinically observed body asymmetry in patients with localization related epilepsy Although these changes are definite, they can be subtle and special attention is necessary Hence, detection of body asymmetries in patients with a seizure disorder is a useful clinical clue for the diagnosis of complex partial seizure as well as the likely lateralization of seizure origin contralateral to the atrophic limbs

43. Clinical Asymmetry

44. Proper First Response Stay calm Remove dangerous items from the immediate area Do NOT try to restrain the patient Note the time the seizure begins Keep onlookers away Activate the emergency medical system if any seizure lasts for more than 10 minutes or if the patient has three or more seizures within a short time Speak quietly and calmly remove the patient from a dangerous or embarrassing environment by guiding them to a safe location and stay with the patient until they are alert

46. Pediatric Cancer Childhood cancer is a relatively uncommon disease affecting approximately 12 of 100,000 children The three most frequent major childhood cancers, comprising about 69% of all childhood neoplasms are: - leukemias (30.1% of all cancers diagnosed among children below 15 years of age) -central nervous system tumors (27.8%) - lymphomas (11.0%)

47. Pediatric Cancer Patient:  Survival Entering into the 21st century, an estimated 1 in every 900 young adults between the ages of 16 and 44 is a survivor of childhood cancer A survivor of childhood cancer is defined as one who has been free of disease for 5 years and off therapy for 2 years The overall survival rate for all types of childhood cancer is now approaching 80%

48. Impact of Treatment Both chemotherapy and radiation therapy given to the growing individual will have consequences for growth, dental development, and craniofacial growth The caries risk may also be increased due to salivary dysfunction It has been shown that although ideal treatment results are not always achieved, orthodontic treatment does not produce any harmful side effects

49. Effects of Treatment Late effects of treatment (radiation and chemotherapy) include: Organ dysfunction Decreased growth Second malignant neoplasm Early mortality Reduced bone mineral density (increased fractures) Decreased fertility Adverse psychosocial effects

50. Treatment effects on cranial development In a sample of 97 children diagnosed with ALL (Acute Lymphoblastic Leukemia) before 10 years of age, treated with combination chemotherapy and cranial irradiation, and followed at least 5 years after diagnosis, the main finding was that patients younger than 5 years at the commencement of anticancer therapy had a markedly increased risk of craniofacial aberrations, characterized by mandibular retrognathism The growth repressive action of irradiation has been explained to be due to growth hormone deficiency in children who receive cranial radiation Several studies stress the importance of growth hormone for a normal mandibular growth Although several animal studies indicate that various chemotherapeutic agents used in anticancer therapy are potentially growth restricting, the clinical effect in humans seem to be fairly moderate

51. Long term effects of treatment Holtgrave and colleagues studied long-term effects of antineoplastic chemotherapy and radiotherapy on dentofacial development in 26 children with solid tumors treated with chemotherapy alone and in 34 patients with ALL treated with intensive chemotherapy and cranial irradiation to the neurocranium There was a marked long-term effect on dental development, whereas the effect on craniofacial dimensions was minor, including a 5% growth reduction in the distances sella-nasion, sella-pogonion, and articulare-pogonion in children who received radiation therapy

52. Orthodontic considerations Strategies used by orthodontists in treating this patient group may include: using appliances that minimize the risk of root resorption low force application accepting a compromised treatment result by simplistic mechanics terminating the treatment earlier than normal not treating the lower jaw It is advised to postpone the start of orthodontic treatment at least 2 years after completion of cancer therapy Since radiation therapy has a growth-suppressive effect, especially on cartilage growth , avoid treating a skeletal Class II malocclusion with growth modification

53. Orthodontic Treatment and Extractions There are no reports on occurrence of osteoradionecrosis after tooth extractions in children treated for malignancies In the group of children subjected to orthodontic treatment, healing after extractions was uncomplicated Since orthodontic treatment should not be started until 2 years after completion of cancer therapy, extractions for orthodontic indications should likewise be deferred until that time

54. Orthodontic Considerations Antineoplastic treatment results in decreased resistance to infections and atrophy of the oral mucosa Patients are at increased risk of complications related to anything that might irritate the mucosal surface To minimize this risk, nonirritating orthodontic appliances should be a consideration in the orthodontic treatment planning of these patients Regular rinsing with artificial saliva and daily topical fluoride application are recommended Because of the reduced regeneration capacity of the mucous membrane even minor irritation from orthodontic appliances can lead to severe ulceration Should the patient require additional chemotherapy or radiotherapy during the course of their active orthodontic therapy, appliances should be removed to minimize the potential for oral complications Once the patient is in remission and the prognosis is considered good, orthodontic therapy can recommence

55. Cardiac Disease, Bleeding Disorders and Asthma While orthodontic therapy has been historically considered to be completely noninvasive, specific orthodontic procedures may place some patients at risk for serious complications Among the most common of these conditions are those associated with cardiac disease, bleeding disorders, and asthma

56. Orthodontics and Bacteremia Although most orthodontic treatment is minimally invasive, the placement and removal of orthodontic bands has been suggested to produce bacteremias The actual data to support this hypothesis are sparse McLaughlin and colleagues studied the incidence of bacteremias after orthodontic banding in 30 healthy adults Elastomeric separators were placed 1 week before the placement of a single band on a permanent first molar Blood samples for culture were taken before and 1 to 2 minutes after band placement Bacterial cultures revealed that the frequency of bacteremias following banding was 10% compared with 3% in the preoperative sample

57. Bacteremia The impact of gingival health on bacteremias associated with band placement can be further appreciated when one compares the incidence of bacteremia following matrix band placement between individuals without gingival inflammation (0%) and those who had gingivitis associated with bleeding (32%) From a risk standpoint, the frequency of banding-induced bacteremias appears to be less than that reported for flossing (20%) or toothbrushing (25%)

58. Risk assesment Patients at HIGH RISK are those with a prior history of endocarditis, those who have prosthetic valves or surgically corrected systemic pulmonary shunts or conduits, or those with complex cyanotic congenital heart disease (tetrology of Fallot) Patients at MODERATE RISK are those with congenital cardiac malformations, acquired valvular dysfunction (such as that caused by rheumatic fever), hypertrophic cardiomyopathy, and mitral valve prolapse with regurgitation Patients at NEGLIGIBLE RISK for endocarditits, defined as being no more likely to develop BE than the general population, are those with secundum atrial septal defects, surgical repair of atrial or ventricular septal defects or patent ductus arteriosus, previous coronary artery bypass grafts, mitral valve prolapse without valvular regurgitation, innocent heart murmurs, previous Kawasaki disease or rheumatic fever without valvular dysfunction, cardiac pacemakers, and implanted defibrillators

59. Most Recent ADA changes The major changes in the updated recommendations include the following: The committee concluded that only an extremely small number of cases of infective endocarditis might be prevented by antibiotic prophylaxis for dental procedures even if such prophylactic therapy were 100 percent effective IE prophylaxis for dental procedures should be recommended only for patients with underlying cardiac conditions associated with the highest risk of adverse outcome from IE For patients with these underlying cardiac conditions, prophylaxis is recommended for all dental procedures that involve manipulation of gingival tissue or the periapical region of teeth or perforation of the oral mucosa

60. Most recent ADA recommendations

61. Antibiotic Prophylaxis Recommendation

62. Prevention of Infective Endocarditis Three management guidelines form the basis for patients at risk of bacterial endocarditis: � Communication with the patient�s physician to confirm that a risk for bacterial endocarditis truly exists � Aggressive pre-treatment and intra-treatment oral hygiene to minimize the presence of gingival inflammation � Prudent use of prophylactic antibiotic therapy Prevention of Infective Endocardititis: Guidelines from the American Heart Association: Wilson, Walter (et. al) Am Dent Assoc 2008;139;3S-24S

63. Premedication Protocol The current recommendations for endocarditis prophylaxis by the American Heart Association are a single dose of Amoxicillin (2 g in adults or 50 mg/kg in children) administered 1 hour before the procedure For penicillin-allergic patients, Clindamycin (600 mg for adults and 20 mg/kg for children) If a patient forgets to take his or her premedication, or if unanticipated bleeding occurs, the American Heart Association guidelines suggest that antibiotic given at the time of treatment or up to 2 hours from the time of insult is effective

64. Bleeding Disorders Effective hemostasis is the consequence of a sequence of events in which platelets and plasma proteins produce clotting Defects in either may result in a clinically relevant coagulopathy with consequent bleeding Bleeding disorders result from qualitative or quantitative platelet deficiencies, or inadequate or insufficient levels of plasma-clotting factors

65. Etiology of Bleeding Disorders Platelet deficiencies of interest to the orthodontist are associated with conditions that result in a reduction of platelets (thrombocytopenia) Thrombocytopenia may result from a reduction in the production of platelets caused by disruption of the bone marrow The most likely sources for this etiology are malignancies involving the bone marrow (leukemia) or autoimmune conditions in which the platelet-producing cells in the marrow are destroyed (aplastic anemia)

66. Leukemia and Gingival Bleeding Leukemia is among the most common malignancies of patients in the most frequently orthodontically treated age groups Gingival bleeding caused by thrombocytopenia often heralds the onset of acute leukemia Unlike most gingival bleeding, which is elicited by some type of provocation, gingival bleeding associated with profound thrombocytopenia is spontaneous Spontaneous gingival bleeding is associated with platelet counts of 20,000 cells/mm3 or less (normal 150,000�450,000 cells/mm3) Because orthodontists see patients frequently, they are often in the position of being the first health care provider to recognize this early sign of leukemia

67. Congenital bleeding disorders In contrast to platelet-related bleeding disorders, factor-related diseases are most often congenital As a result, the orthodontist should be able to determine the presence of these conditions before the initiation of treatment Three congenital clotting factor deficiencies account for more than 90% of inherited disorders: Hemophilia A (def of Factor VIII) Hemophilia B (def of Factor IX) Von Willebrand�s disease (defects of von Willebrand�s factor ) **most common congenital bleeding disorder***

68. Orthodontic associated risk: Extractions For patients with a congenital bleeding disorder, probably the biggest orthodontic-associated risk is associated with extractions associated with treatment In these cases, the administration of factor replacement along with Amicar or tranexamic acid is prudent Amicar (aminocaproic acid) and tranexamic acid are anti-fibrinolytic agents that prevent the breakdown of the clot in the extraction site, allowing for better organization, and thereby decreasing the likelihood of postoperative bleeding

69. Precautions with Bleeding Disorders To minimize risk and cost to the patient, it seems most reasonable to perform all planned extractions at a single visit It is imperative that this group of individuals be in absolute gingival health before the commencement of treatment Care should be used in the placement and removal of orthodontic hardware to minimize the risk of mucosal injury Elastomeric modules are preferential to wire ligatures Overall treatment should be performed as expeditiously as possible

70. Asthma Episodic narrowing of the airways that results in breathing difficulty and wheezing Asthma is most often the result of an inherited immunologic hypersensitivity (allergic) disorder

71. Prevalence Almost half of cases of asthma develop before age 10 Prevalence of the condition was highest in blacks (15.8%), intermediate in whites (7.3%) and Asians (6.0%), and lowest in Latinos (3.9%) These differences were unrelated to income or access to medical care The severity of asthma, based on limitation of activities and need for acute medical care, was most notable among black and Latino children

72. Management Considerations The first objective is the prevention of acute asthmatic attacks and the key to this is the identification of patients at risk Obtain information regarding the severity of the disease (limitation in activities, emergency room visits, etc.), medications, and factors that precipitate an attack

73. Management Considerations Communication with the patient�s physician will assist in risk assessment Orthodontic treatment should probably be deferred in patients who report symptomatic disease or have frequent flares despite being adequately medicated For patients at low or moderate risk, since anxiety and stress are often associated with acute attacks, morning appointments when the patient is rested, short waiting times, and visits of limited duration are most desirable

74. Management Considerations The orthodontist should assure that the patient has taken his or her medication and, if appropriate, has his or her inhaler present if needed during the appointment Patients with asthma may be sensitive to several specific medications including the erythromycins, aspirin, antihistamines, and local anesthesia containing epinephrine

75. Side Effects of Asthma Treatment Chronic use of inhalers, especially those containing steroids, may result in a predilection for the development of oral candidiasis and xerostomia If noted candidiasis can be treated with topical antifungal agents such as Nystatin Xerostomia enhances the risk of caries, therefore, aggressive oral hygiene, supplemental topical fluorides are essential

76. Asthma and Root Resorption It has been suggested that orthodontic-induced external root resorption occurs with greater frequency in patients with asthma than in the non-asthma population McNab and colleagues compared the incidence and severity of external root resorption following fixed orthodontic therapy between patients with asthma and a healthy population They found that while the incidence of external apical root resorption was elevated in the asthmatic population, the severity of resorption was the same between groups It would seem prudent, therefore, for orthodontists to disclose the heightened risk of external root resorption to patients before initiating treatment

77. Asthma and Root Resorption: Study Root Resorption and Immune System Factors in the Japanese The objective of this study was to determine whether there is an association between excessive root resorption and immune system factors in a sample of Japanese orthodontic patients The records of 60 orthodontic patients (18 males, age 17.7 � 5.7 years; 42 females, age 16.4 � 6.0 years) and 60 pair-matched controls (18 males, age 15.9 � 4.5 years; 42 females, age 18.5 � 5.2 years) were reviewed retrospectively The pretreatment records revealed that the incidence of allergy and root morphology abnormality was significantly higher in the root resorption group The incidence of asthma also tended to be higher in the root resorption group From these results, we concluded that allergy, root morphology abnormality, and asthma may be high-risk factors for the development of excessive root resorption during orthodontic tooth movement in Japanese patients

78. References

79. References