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DT Middle East and Africa

DENTALTRIBUNE Middle East & Africa Edition Media CME 7 ical problems in this age group include in- fective endocarditis, bleeding disorders, leukaemia, diabetes, cystic fibrosis, juve- nile rheumatoid arthritis and renal fail- ure. An even higher percentage of adult patients may be afflicted by a variety of medical problems that involve one or more of the tissue systems. These condi- tions, and the medications used to treat them may have profound effects on the re- sponse of dental and para-dental cells to mechanical loading. Endocarditis is a life-threatening dis- ease, requiring primary prevention in the form of administration of antimicrobial agents prior to certain orthodontic proce- dures. The orthodontist must weigh the risk of endocarditis against the risk of an adverse reaction to the prescribed antibi- otic therapy. Fortunately, most orthodon- tic procedures do not cause bacteraemia. Lucasetal.(2002)obtainedbloodsamples fromchildren30secondsaftertakingden- tal impressions, separator placement, band placement and insertion of an ad- justed arch wire. Significant bacteraemia was found only after separator placement. Orthodontic braces, fixed and remov- able,canaccumulatebacterialplaquethat may be harmful to oral soft and hard tis- sues. This problem has been addressed by adding antimicrobial agents to bracket bonding materials, elastic bands and crown coating varnishes. The addition of benzalkonium chloride to a composite resin added antimicrobial properties to the compound without altering its me- chanical properties (Othman et al., 2002). Likewise, coating teeth in orthodontic pa- tients with a sustained-release chlorhexi- dinevarnishdecreasesStreptococcusmu- tans levels in the patients’ saliva (Beyth et al., 2003). Childrentreatedforchildhoodcancers with both radiation and chemotherapy of- ten exhibit disturbances in dental devel- opment, such as tooth agenesis, teeth with short roots or with no roots altogether. A retrospective analysis of treatment out- comeintenorthodonticpatientswithsuch a background revealed that five had been treated with lighter forces than usual, one displayed root resorption, and four achievedunsatisfactoryresults(Dahllofet al., 2001). The development of inflammation in dental and para-dental tissues during the course of orthodontic treatment implies that circulating plasma and leukocytes migrate out of capillaries, and interact with native cells. The blood plasma may contain endogenous hormones produced by endocrine glands, as well as a variety of molecules derived from consumed drugs and nutrients. Some of these molecules may interact with para-dental target cells, augmenting or inhibiting the effects of mechanical forces on these cells. One of the main complications of such interac- tions is the development of root resorp- tion. Diabetes mellitus afflicts 3 to 4% of the population, and is characterised by hyper- glycaemia caused by the body’s deficient management of insulin. There are two maintypesofdiabetes:type1andtype2.In type 1, there is a total deficiency in insulin secretion, while in type 2 there is a combi- nation of resistance to insulin action and insufficient compensatory insulin secre- tion.Diagnosisandmonitoringofdiabetes isbasedonbloodglucoseconcentrationor glycosylated haemoglobin concentration. Oral manifestations of the disease include xerostomia, chronic gingivitis and peri- odontitis, excessive loss of alveolar bone and PDL, poor healing of wounds, and soft tissue lesions, both candidal and non-can- didal (Bensch et al., 2003). Orthodontic treatment should be combined with fre- quent dental care sessions and mainte- nance of excellent oral hygiene. The mag- nitude of applied forces should be smaller than usual, reflecting the loss of dental support tissues. Periodontitis, acute or chronic, may be present before the onset of orthodontic treatment, or occur during the course of treatment owing to the accumulation of a bacterial plaque around the braces. Pe- ripheral blood monocytes obtained from individualswithchronicperiodontitissyn- thesised large amounts of pro-inflamma- torycytokineswhenincubatedinvitrowith bacterial lipopolysaccharides. If such primed monocytes find their way into strained para-dental tissues, their in- creasedproductionlevelsofcytokinesmay increase the risk of root resorption. An in- dicator of such an increased risk may be theconcentrationofcytokinesinthegingi- val crevicular fluid. Previous studies re- ported on increased levels of cytokines, such as tumour necrosis factor- and inter- leukin-6 in the gingival crevicular fluid of orthodontically treated teeth in humans (Kim and Park, 2000). The origin of these cytokines is most likely PDL cells. Allergies and asthma are conditions in- volving periodic productions of large amounts of pro-inflammatory cytokines in the airway mucosa and the skin. Primed leukocytes derived from these tissues may travel through the circulation into the ex- travascular space of the tissues surround- ing orthodontically treated teeth. Conse- quently, patients with a history of allergies and/or asthma appear to be at a high risk of developing excessive root resorption dur- ing the course of orthodontic treatment (Davidovitch et al., 1999). Hence, it is pos- tulated that any inflammatory condition, such as gastro-enteritis, arthritis and thy- roiditis, may increase the risk of orthodon- tic root resorption. Allergy manifestations in orthodontics are infrequent, although the frequency of allergicdiseasesintheindustrialisedworld is rising. The WHO reports that 15% of the population has had or will have an allergic disease. Allergicreactionstoorthodonticmateri- alscandevelopduringtreatment,manifest- ingasurticaria,angioedema,stomatitisand cheilitis (Beaudovin et al., 2003). Metals in orthodontic appliances that can induce an allergic reaction are nickel, chromium, cobaltandtitanium.Otherallergy-inducing materials include latex, resins, adhesives andmethylmethacrylates.Whenareaction thatappearstobeallergy-relatedisdetected in an orthodontic patient, there should be referral to an allergist for advice. Close col- laborationbetweentheorthodontistandthe allergist is essential for each future stage of the orthodontic treatment in order to avoid further complications. A method to detect patients sensitive to orthodontic alloys was developed in the form of an in vitro cell proliferation assay (Marigo et al., 2003). The best parameters for inducing the strongest cell proliferation response were 10 µg/ml nickel sulphate, 10 % autologous serum, and 200,000 cells. With this method, it was possible to distinguish between nickel- sensitive and non-nickel-sensitive pa- tients. Moreover, it was found that expo- sure to nickel alloys for periods longer than two years may lead to the develop- ment of oral tolerance mechanisms that modulate nickel sensitivity. Consumption of low or moderate amountsofalcoholmayhavebeneficialef- fects on the cardiovascular system, but chronicingestionoflargeamountsofalco- hol on a daily basis may have devastating effects on a number of tissue systems, in- cluding the skeletal system. Alcoholism may lead to severe complications, such as liver cirrhosis, neuropathies, osteoporo- sis, and spontaneous bone fractures. Cir- culatingethanolinhibitsthehydroxylation of vitamin D3 in the liver, thus impeding calcium homeostasis. In such situations, thesynthesisofparathyroidhormoneisin- creased, tipping the balance of cellular functions towards enhanced resorption of mineralised tissues, including dental roots, in order to maintain normal levels of calcium in the blood (10 mg). Therefore, chronic alcoholics receiving orthodontic treatment are at a high risk of developing severerootresorptionduringthecourseof orthodontic treatment. Demyelinating diseases such as multi- ple sclerosis are associated with an abnor- mallyhighincidenceoftrigeminalneural- gia.Inmultiplesclerosis,afferentnervefi- bres lose their myelin sheaths, leading to short circuits between axons. Such shorts in the trigeminal nerve may precipitate trigeminal neuralgia. Orthodontic treat- ment evokes an inflammatory reaction in para-dentaltissues,includingpainfulsen- sations that travel in an antidromic fash- ion from strained para-dental sensory nerve endings. If areas of demyelination are present along the way to the Gasserian ganglion, trigeminal neuralgia may en- sue. Psychological stress is a common com- ponent of everyday life. It may be found to exist in patients prior to the onset of ortho- dontic treatment, or it may develop during the course of treatment owing to discom- fort,resentmentorotherreasonsunrelated toorthodontics.Psychologicalstressaffects the hypothalamic-pituitary-adrenal (HPA) axis, and the immune system. Since osteo- clasts and odontoclasts are derived from the immune system, modification of their function by psychological stress may affect theprocessofrootresorption.Arecentsur- vey revealed that orthodontic patients with psychological stress were at a high risk of developing excessive root resorption dur- ing the course of orthodontic treatment (Davidovitchetal.,1999).Furthermore,pa- tients who are non-compliant, poor co-op- eratorsandthosewhofrequentlybreakap- pointments and/or appliances do it most likely because of psychological stress. Of- ten, these non-compliant individuals ex- press their objection to orthodontic care that had been imposed on them by their parents through their behaviour. In these individuals, the rate of orthodontic root re- sorption was found to be significantly higher than in compliant patients. Amongst the reasons for partial and to- tallossofscalphairispsychologicalstress, probably through effects on the HPA axis. Davidovitchetal.(1999)reportedacaseof an adolescent orthodontic patient who de- veloped alopecia totalis during orthodon- tictreatment.Areviewofthecaserevealed a normal medical background with the presence of a persistent psychological stress owing to exposure to orthodontic mechanotherapy. Consequently, the pa- tient’s paediatrician and the endocrinolo- gist concluded that his alopecia had been most likely caused by psychological stress evoked by the orthodontic treatment. Part 2 of this article will be published in DT ME 10 (2011). A complete list of references is available from the publisher. DT