A STUDY OF TOOTH WHITENINGSAFETY,EFFICACY AND MECHANISM ....doc

a study of tooth whitening: safety, efficacy and mechanism of action gerard kugel 33 a study of tooth whitening: safety, efficacy and mechanism of action 44 a study of tooth whitening: safety, efficacy and mechanism of action dipartimento di scienze odontostomatologiche universit di siena viale bracci 53100 siena prepared for the graduate committee on june 13, 2004 gerard kugel boston, ma, usa 55 the present thesis is respectfully submitted to prof piero tosi, rector of the university of siena, to prof alberto auteri, dean of the faculty of medicine, university of siena, to prof egidio bertelli, vice-dean of the faculty of medicine and director of the department of dental science, and to prof marco ferrari, pro-rector for international affairs and president of dental school, university of siena. graduate committee: promotorprof. dr marco ferrari committeeprof. dr c.l. davidson prof. dr f. tay prof. dr toledano prof. dr balleri 66 this thesis was prepared at tufts university school of dental medicine, boston ma, usa and at the school of dentistry university of siena, italy. contents chapters 1introduction 2a novel low dose tooth-whitening delivery system efficacy and safety: a randomized and controlled clinical trial 3concentration and dose response clinical trial evaluating the peroxide concentration response of a polyethylene strip delivery system over 28 day 4light activated tooth whitening clinical evaluation of a 35% hydrogen peroxide in-office whitening system 5chemical vs light activated tooth whitening clinical evaluation of chemical and light-activated tooth whitening systems 6tooth whitening and its effect on enamel and dentin daily use of whitening strips on tetracycline stained teeth: comparative results after two months 7long term hydrogen peroxide exposure and its effect on dentin comparative study of 6.5% hydrogen peroxide bleaching strips on tetracycline stain: clinical response after six months daily use 77 8paint on delivery systems a clinical comparison of two paint on whitening systems 9maintenance of whitening clinical study to evaluate the maintenance of whitening after bleaching treatment 10intrapulpal temperatures with light activated whitening effects of a light activated bleaching system on pulp chamber temperature in vitro 11effect of tooth whitening on enamel an exploratory study using sem to evaluate the enamel surface effects in vivo of a 6% hydrogen peroxide strip bleaching system with that of a 2.5% chlorite tray bleaching system 12summary and conclusions 88 chapter 1 introductiontooth whitening the dental profession has succeeded in reducing caries and periodontal diseases and as a result dental problems have decrease to the point where esthetic improvements are now more attainable (burrell 19971). one of the fastest growing areas of esthetic dentistry today is the management of the discolored and hypoplastic dentition. the demand for an improved appearance and a whiter smile has made tooth whitening a very popular dental procedure. tooth whitening, sometimes referred to as “bleaching”, offers a conservative treatment option for discolored teeth in comparison to resin bonded composites, porcelain veneers or crowns 2,3(papathanasiou 2000, 2001). candidates for whitening procedures include patients whose teeth are stained by aging, chromogenic foods, endodontic treatment, tetracycline use and 99 smoking or use of other tobacco products. success of the treatment depends on type, intensity and location of the discoloration and a careful diagnosis by the practitioner. history of bleachingtooth whitening: many attempts to find an effective bleaching method have been made through out the history of dentistry. the desire to have whiter teeth dates back at least 2000 years ago. during the first century the romans physicians claimed the use of urine, especially portuguese, to brush the teeth would whiten the teeth (dale, esthetic dentistry4). barber-surgeons used a solution of nitric acid to lighten the teeth after using a course metal file to abrade the enamel (dale, esthetic dentistry4), practice until late eighteenth century. in 1895 it was reported the combination use of pyrozone 25% and electricity to bleach the endodontically treated teeth (westlake a, 1895). 5. later on, in 1916, it was stated the use of hypochloric acid to treat endemic fluorosis (adams, 1987). 6. in 1939 it was advocated the use of 30% hydrogen peroxide, ether and heat to treat fluorosis staining (younger, 19397). in 1966, it was promoted the combination use of hydrochloric acid and hydrogen peroxide to remove “brown stain from mottled teeth” due to a chronic endemic dental fluorosis mcinnes, 19668. it is interesting to observe that most of the efforts of tooth whitening at the time were done evolving extrinsic enamel stains. the early efforts to whiten teeth relied on the assumption that the process involved the removal of extrinsic enamel stain. the mechanism of action was poorly understood. it was only on 1970 that cohen and parkins first published a method for bleaching the discolored dentin of young adults with cystic fibrosis who has undergone tetracycline treatment 9(cohen, 1970). t. this publication indicated that the mechanism of tooth whitening using hydrogen peroxide involves penetration to the dentin. in 1976, nutting and poe introduced the walking bleach technique, which uses 35% hydrogen peroxide and sodium perborate for 1010 nonvital teeth bleaching 10(nutting, 1976). . the breakthrough in tooth whitening was in 1989 when haywood and heymann published the nightguard vital bleaching technique. technique 11. this is procedure is still widely used among the dental community as the take-home bleaching system. tooth whitening systems tooth whitening with various concentrations of peroxide has been demonstrated to be safe and effective in a variety of regimens, including in-office procedures, dentist-prescribed and supervised home treatments and over the counter system approaches.( 12reference? li?) m. most dental practices in the united states offer some form of tooth whitening system. and as many as one out of five patients have their teeth whitened. a) take- home system: the most common regimen is the at-home use for 2 to 4 weeks, based on the color of the teeth at the start of whitening 13,11 (kugel 2000 and haywood). .the use of hydrogen peroxide for removing intrinsic stains from vital teeth has been used for many years. haywood and heymann published the first publication article describing night guard vital bleaching in 1989 11. the dentist prescribed home-applied technique most commonly between 10% to 22% carbamide peroxide. a tray is fabricated from a model of the patientspatients teeth using a soft plastic nightguard. this tray is the loaded with carbamide peroxide gel and seated over the teeth for approximately 2 hours. the most commonly prescribed concentrations are 10% to 22% carbamide peroxide. 1111 the advantage of the take-home systems is the decreased cost (with minimal in-office time required to fabricate trays and educate the patient on the take-home procedure). when compared to the in office bleaching options. the major disadvantages associated with take- home systems are: (a) they require significant patient compliance with the number of applications usually involving 1-2 hours twice a day or overnight wear, and (b) the entire treatment usually takes at least four weeks. b) in-office system: the most acceptable applications involve are in-office techniques, dentist prescribed take-home systems or a combination of both. the in-office bleaching technique generally employs a 15%, 30% or 35% hydrogen peroxide bleaching agent (heated or non-heated). the advantages of the in-office procedure are: (a) it requires minimal patient compliance, and (b) immediate results are attainable. the disadvantages to this treatment are: (a) chair-time requirement, and (b) cost to the patient. it is important to note that this procedure usually requires multiple office visits. c) combination technique: by combining the two techniques (in-office and take-home), there is a reduction in the amount of time and the need for repeated office visits as well as the expense associated with in-office bleaching as a stand-alone technique 14(garber 1997) the combined technique increases overall success and patient satisfaction. (kugel 1997).this procedure involves the use of a high concentration of hydrogen peroxide (35%) delivered chair side for one hour followed by a take 1212 home regimen of 5days. this is often followed by an additional chair side application. 15(kugel 1997). d) whitening strips: a new method involves using a 5.3% hydrogen peroxide-impregnated polyethylene strip (crestwhitestrips) for 30 minutes twice daily. this method is recommended for maintaining already whitened teeth. it can also be a good option and for offering treatment to patients who cannot afford the cost of other whitening treatment or who do not have the time for multiple dental visits for tray fabrication 13( kugel, 2000). it was also published in 2002 the use of the whitening strips for tetracycline stained teeth 13 development of this flexible, polyethylene whitening strips allows for consistent bleaching using shorter contact times. fixing the daily strip regimen at 30 minutes per day, a randomized, double blind, a double placebo-controlled clinical study was conducted to evaluate the effects of increasing the dosing regimen on tooth shade 17 (gerlach et al., 2001) also, an in vitro study explored the impact of varying concentration of carbamide peroxide ranging from 0.4% to 10% on bleaching efficacy (harris et al., 2001) and the impact of increasing hydrogen peroxide concentration on bleaching strip efficacy and tolerability under clinical conditions 18 (mcmillan et al., 2001) these studies demonstrated that a modest increase in peroxide concentration on a flexible bleaching strip results in increased whitening effectiveness, without adversely impacting on overall tolerability. the main drawback is that they are limited to the anterior teeth and cannot be easily adapted to the malposed teeth. 1313 e) light activated whitening systems: technological advances in dentistry make it possible for the practitioner to deliver the highest level of care in an efficient and often economical way. with tthe introduction of light activated devices such as plasma arc, light emitting diodes (led), argon lasers, metal halide and xenon-halogen lights, being promoted as “the future of dentistry,” by dental manufacturers have helped create a public awareness and demand for the so-called: “ llight enhanced tooth whitening systems”. in 2002 one article and more recentlycontroversial two papers were published evaluating the efficacy of light activated bleaching agents in 2002. one the first studyarticle reportedreported positive results19, whereas. the the other articles concluded the opposite findings 20, 321. reviews of these articles were these articles either in supportmaintained 224 or discredited questioned the findingsresults 235. it is apparent that tthe dental profession needs still needs more evidence of its effectiveness in order to provide for better and more efficient treatment. the lack of knowledge is to the detriment of the dentist and patient alike. the need for more knowledge becomeshigh demand for “up to date” dental office by patients and clinicians even stimulates more important as manufacturers to inundate the dental profession with advertisements emphasizing that light activated tooth whitening is “the state of the art” and should be part of the armamentarium of the office, with not clear evidence of its usefulness “up to date” dental office. the use of hydrogen peroxide (h202) for bleaching teeth has been evident with use of heat or not 24. bleaching is the most conservative treatment for discolored teeth when compared to resin bonded composites, porcelain veneers or crowns. it offers a simple and economical approach to changing the color of teeth. success of the treatment depends on a careful diagnosis by the practitioner. candidates for 1414 whitening procedures include patients whose teeth are stained by aging, chromogenic foods, endodontic treatment, tetracycline use and smoking or use of other tobacco products. acceptable tooth whitening techniques include the in-office technique, dentist-prescribed home- applied technique, or a combination of the two. the use of hydrogen peroxide (h202) for bleaching teeth dates back to 1995 6. to reducein order to gain treatment time, clinicians have attempted to accelerate the degradation of h202 by using heat or light. in 1970, cohen and parkins introduced a technique for bleaching discolored teeth, such as tetracycline stained-teeth, using hydrogen peroxide and a hand-held heating source 79. most clinicians know that hydrogen peroxide is a bleaching agent that can attain a desired whitening effect. bleaching can also be accomplished with carbamide peroxide, a lower concentration of hydrogen peroxide and urea, which breaks down to 3.6% hydrogen peroxide 8,9.the degree of whitening correlates directly with the amount of contact time and concentration of the active ingredient, the ph and viscosity 9. the side effects are usually diminished when lower concentrations are used. the in-office bleaching treatment using hydrogen peroxide and an accelerating source (heat or light) were predominant until 1989 when haywood published the first article on nightguard vital bleaching using carbamide peroxide 10. currently, the in-office bleaching technique employs a 15 - 40% hydrogen peroxide bleaching agent (heat activated or not), while the dentist prescribed home-applied technique most commonly uses a 10 - 15% carbamide peroxide gel. the advantages of an in-office procedure are twofold. it does not require patient compliance and immediate results can be accomplished. the disadvantages are the chair side time involved and the cost to the patient, as the procedure usually requires multiple visits. light-activated chair side bleaching systems potentially offer the benefit of being less time-consuming while producing faster results. 1515 recent in vitro study has shown that the use of intense lights does elevate temperature of the bleaching material and as a result caused an increase in intrapulpal temperature. this may have an impact on post bleaching tooth sensitivity and pulpal health 25 t. another research in vitro has verified that the use of laser-activated hydrogen peroxide did not produce any perceivable colour change 26. light-activated chair side bleaching systems probably offer the benefit of being less time-consuming while producing faster results.he introduction of very high intensity plasma arc lights and argon lasers meets the need of an ever increasing demand for whiter teeth. the assumption is that clinically tolerable levels of heat will speed the breakdown of h2o2 tooth bleaching chemicals and this accelerated h2o2 breakdown will cause teeth to lighten more rapidly per unit time. in a recent study the decomposition of hydrogen peroxide was measured by the amount of oxygen released. the data from this study indicated that at temperatures of up to 85 c accelerated decomposition of the 35% h2o2 was minimal when compared to the control gel 20. research in vitro has demonstrated that the use of laser-activated hydrogen peroxide did not produce any perceivable color change 11. another recent in vitro study, and one which should be of concern to the practitioner, has shown that the use of these intense lights does elevate temperature of the bleaching material and as a result caused an increase in intrapulpal temperature. this may have an impact on post bleaching tooth sensitivity and pulpal health 12. the use of light activated bleaching system to accelerate the bleaching process is still on question and more evidence needs to be gathered in order to make a more precise assertion of its effectiveness. 1616 the efficacy of a bleaching treatment can be determined through first or second evaluators or various technical methods. the use of a shade guide, colorimeter, or computer digitization to measure color change over time has been currently included in clinical trials to assure efficacy assessment 13, 14, 15. f) toothpaste: many types of toothpaste are available in the market as tooth whitening products, but only a small number of them show stain removal ability and effectiveness. most of these toothpastes do not contain bleaching agents in their formulation. the ones that do have very low bleach concentration and contact times relatively too short to be effective 27. (sharif 2000). whitening toothpastes contain mild abrasives to remove surface stains. the peroxide content in the toothpastes are very low ( 1(1% or less )less), also the exposures of the toothpastes on the tooth is minimal hence any whitening mi minimal 28.11. g) over the counter products: easy availability of over the counter whitening products has made whitening of teeth more popular amongst people of all ages. there are different types of over the counter products like whitening dentifrices, tray based, whitening strips and the recently introduced brush applications. the latest inclusion to otc products is a brush technique. this technique is non- tray based paint on application. gingival irritation can be prevented due to the ease in application. over the counter bleaching kit requires the consumer to use either a prefabricated tray or fabricate their own semi-molded tray then fill it with supplied bleaching agents. these types are less than ideal because the trays are not custom fitted and the formulation is not sophisticated as those dispensed by the dentist 29. .10 1717 mechanism of aactionechanism of action many studies have been conducted to evaluate the effectiveness of various bleaching materials and techniques 27, 30,mokhlis et al. 2000, 31,chr