Volume 51 • Issue 3 • 2006 177

Background.—The use of night guard vital bleaching iswidely practiced to lighten natural tooth color. The whiten-ing process is accomplished through direct contact of thewhitening product on the surface of the teeth for an ex-tended period. The material of choice for this bleaching iscarbamide peroxide. Among the potential adverse effectsof this process are concerns about enamel demineraliza-tion. Microcomputerized tomography (µCT) has beenused to map the distribution of mineral in teeth nonde-structively. Its use in assessing the effects of dental materi-als on the mineral content of enamel and dentin is limited.However, it was chosen to assess the possible demineral-ization effect of 10% carbamide peroxide on enamel aftercyclic bleaching.

Methods.—Twelve human molar tooth sections under-went µCT in vitro to evaluate their mineralization. The sec-tions were exposed to 10% carbamide peroxide 8 hours aday for 15 days. Repeat tomography images were obtainedto evaluate the mineral content before and after bleachingfor 144 regions of interest.

Results. —The comparison of mineral content beforeand after bleaching indicated a significant difference in thehydroxyapatite equivalent mineral content in the region ofinterest corresponding to the outer 50 µm of enamel. Afterbleaching, the mineralization of the enamel was reducedfrom baseline values.

Discussion.—The use of µCT to assess mineralizationprovided the ability to make comparisons without destroy-ing tooth material. The carbamide peroxide resulted in de-mineralization of the enamel surface up to 50 µm deep.Thus, patients who are susceptible to caries and tooth wearshould use such bleaching methods only after careful con-sideration of the risks.

Efeoglu N, Wood D, Efeoglu C: Microcomputerised tomographyevaluation of 10% carbamide peroxide applied to enamel. J Dent33:561-567, 2005

Reprints available from N Efeoglu, Dept of Restorative Dentistry,Leeds Dental Inst, Univ of Leeds, Worsley Bldg Level 6, ClarendonWay, Leeds LS2 9LU, UK: fax: +44 113 343 6129; e-mail:n.efeoglu@leeds.ac.uk

Clinical Significance.—There have been nonondestructive ways to measure decalcifica-tion of tooth structure by bleaching agents.The use of µCT in this study presented quan-tifiable parameters and suggests demineraliza-tion does indeed occur, in sufficient amountsto warrant caution in subjects subject to cariesor wear.

Bleaching and demineralization

Background.—Patients may be taking low-dose aspirin(75 to 100 mg) as part of their therapy for angina, ischemicheart disease, post-myocardial infarction, post-bypasssurgery, post-angiography/angioplasty, stroke, or transientischemic attacks. Usually the intake of aspirin is halted be-fore surgical procedures, including oral surgery, to avoidthe development of any uncontrollable bleeding. This sus-pension of therapy heightens the risk for the patient to suf-fer thromboembolism, myocardial infarction, or cardiovas-cular accident. Fifty-one patients taking low-dose aspirin

therapy continued their medications through scheduledoral surgery; the results are reported.

Methods.—The patients ranged in age from 45 to 70years and included 32 men and 19 women. The low-doseaspirin therapy had been used for 1 to 15 years, with amean duration of 3.76 years. Measurements of bleedingtime and platelet count were obtained preoperatively.These measures were within normal limits, so the aspirintherapy was continued. All patients underwent outpatient

Oral MedicineLow-dose aspirin therapy and oral surgery

178 Dental Abstracts

surgery under local anesthesia. Their wounds were su-tured, with follow-up examinations conducted after 24, 48,and 72 hours, after 1 week, and after 2 weeks.

Results.—The mean bleeding time was 2.86 minutes,and the mean platelet count was 289 � 103/mm3 for the 51patients. One patient developed excessive intraoperativebleeding, with constant oozing during removal of a thirdmolar. Control was obtained by applying gauze soaked in1% feracrylum solution for 10 minutes. All other patientsresponded to the use of a simple pressure pack and sutur-ing. None of the patients developed bleeding problemspostoperatively.

Discussion.—Based on the findings in this study, mostminor oral surgical procedures can be done safely while pa-tients continue their low-dose aspirin therapy.

Madan GA, Madan SG, Madan G, et al: Minor oral surgery withoutstopping daily low-dose aspirin therapy: A study of 51 patients. JOral Maxillofac Surg 63:1262-1265, 2005

Reprints available from G Madan, Madan Dental Hosp, Ground Flr,B-9/10, Nobles Bldg, Opp Nehru Bridge, Ashram Rd, Ahmedabad,India 380009; e-mail: gautammadan@yahoo.com

Clinical Significance.—Adding credenceto the belief that aspirin need not be dis-continued before most minor surgical pro-cedures, this study demonstrated no unto-ward bleeding. The patient’s medical historyshould be considered in toto.

Background.—Compared to traditional treatment ap-proaches that seek anchorage from teeth or extraoral de-vices, osseointegrated dental implants may provide betterorthodontic anchorage. The success of marginal bone re-modeling resulting from orthodontic treatment dependson various factors, such as the magnitude of forces appliedto an implant, the deformation of the loaded bone, and thebone’s nature itself. Evaluations indicate that within a typi-cal orthodontic range of force, when higher forces are ap-plied to threaded dental implants, the subperiosteal boneformation on the compression side of the implants in-creases. At the same time, bone resorption on the tensionside increases. Additionally, morphometric results indicatethat orthodontically loaded, porous-surfaced (PS) implantsretain marginal bone to a significantly greater height anddevelop more bone-to-implant contact than machined-threaded (MTh) implants loaded to a similar degree. Thenature of the bone remodeling that occurs around PS andMTh implant designs was assessed using fluorochrome la-beling techniques and back-scattered scanning electron mi-croscopy.

Methods.—Three implants of each design were placedin 5 beagles in contralateral mandibular extraction sites.

The implants were allowed to heal for 6 weeks, then abut-ments were placed. One week later, the 2 mesial implantson each side underwent orthodontic loading for 22 weeks.One threaded implant loosened, but the rest maintainedtheir osseointegration over this period. The bone re-sponses around the implants were assessed and com-pared.

Results.—The percent bone area (%BA) differed signif-icantly between the implant types, with the PS implants hav-ing greater %BA values for all conditions and next to all sur-faces. The significant differences were primarily found nextto the coronal implant subregions. The implant types alsodiffered significantly for bone subjected to both tension andcompression, with the PS implants having significantlygreater %BA values. All the coronal zones in control PS im-plants also had higher %BA values than those in MTh im-plants.

For the orthodontically loaded implants of the 2 designs,no significant differences were noted in %BA measured overthe total implant lengths for tension or compression boneregions. Control implants showed significant differences inthese areas.

OrthodonticsImplant surface design and osseointegration