3. All MSIs are single-patient, single-use medical devices.Therefore, they should be used only once and discardedappropriately when removed.1,2

4. All instruments used during the placement of MSIs shouldbe heat sterilized before use (double wrapping is notrequired).1,2

CDC staff continues to monitor the current scientific liter-ature and update infection control recommendations whennew information is available. We appreciate the opportunityto clarify several points in the editorial.

Jennifer L. ClevelandWilliam Kohn

Division of Oral Health, National Center for Chronic DiseasePrevention and Health Promotion, Centers for Disease

Control and PreventionAtlanta, Ga

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doi:10.1016/j.ajodo.2009.09.008

REFERENCES

1. Centers for Disease Control and Prevention. Guidelines for infection

control in dental health-care settings—2003. MMWR(RR-17):1-61.

Available at, http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5217a1.

htm. Accessed September 3, 2009.

2. Rutala WA, Weber DJ, and the Healthcare Infection Control Prac-

tices Advisory Committee (HICPAC). Guideline for disinfection

and sterilization in healthcare facilities. Atlanta, Ga: Public Health

Service, US Departrnent of Health and Human Services, Centers for

Disease Contol and Prevention. Available at, http://www.cdc.gov/

ncidod/dhqp/pdf/guidelines/Disinfection_Nov_2008.pdf; 2008.

Accessed September 3, 2009.

Authors’ response

We thank Dr Wang Jing for his interest in our article andhis comments. We set out to investigate patients with buccaldisplacement of canines before treatment. Thus, no preventiveor therapeutic measures had been taken. Nature had generatedthe buccal displacements, and our aim was to search for cluesto any association of this phenomenon with crowding or spac-ing and with lateral incisor anomaly, and to suggest possibleexplanations for the occurrence. Crowding was not a factorin the experimental group, since the inclusion criteria providedfor a spaced dentition, a priori. Overretained deciduous teethare most probably the result of the displacement, rather thanthe cause, and abnormal tooth bud locations could have beenfound in any of the 3 groups of patients. There was no evidenceto implicate pencil biting as an etiologic factor, any more thanto blame weight-lifting or vegetarianism.

Dr Jing pointed to the mesial movement of molars aftereruption of the premolars and before canine eruption as a factorthat might lead to buccal ectopy of the canine because ofcrowding. This will obviously place such a patient in theBDC-c group, but 1 characteristic of a spaced dentition is a rel-ative lack of mesial migration after the shedding of deciduousteeth—defining the case as a BDC-nc.

We agree that it is equally valid and pertinent, as Dr Jingsuggests, to look at patients with spacing or lateral incisoranomaly as the prime grouping agent and then investigatethe frequency of crowding or spacing and lateral incisor anom-aly. This will likely add new insights into this entire area, but itis a different study!

We set out to contrast crowding (as a cause) with spacing(as a cause); we believe that we achieved it in this study.

Stella ChaushuMasha Bongart

Alev AksoyYocheved Ben-Bassat

Adrian BeckerJerusalem, Israel, and Isparta, Turkey

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American Journal of Orthodontics and Dentofacial Orthopedics Readers’ forum 623Volume 136, Number 5

Buccal canine displacement

In their article in the August issue, Chaushu et al reported thatthe buccal displacement in BDC-nc subjects (buccally displacedcanine, no arch crowding) might also be the result of lack of guid-ance from an adjacent anomalous lateral incisor in addition toa genetically based etiology (Chaushu S, Bongart M, Aksoy A,Ben-Bassat Y, Becker A. Buccal ectopia of maxillary canineswith no crowding. Am J Orthod Dentofacial Orthop2009;136:218-23). I agreewith them in part. Hereare my reasons.

First, many factors can affect canine eruption, includingcrowding, a deciduous tooth or an abnormal tooth bud, or un-healthy habits such as biting a pencil. The authors didn’t tell usthat they eliminated the above effects, and we could not ignorethe individual differences.

Second, even if we eliminated all the effective factors, aswe know, the eruption of canines is later than the eruption offirst or second premolars, so a premolar’s mesial movementis common. This can also result in canine ectopia buccallywithout arch crowding.

Third, in the situation of BDC, all patients who had beendiagnosed with BDC and crowding less than 2 mm (BDC-nc)formed the experimental sample. BDC became a grouping

agent; actually, the authors just investigated the variations inlateral incisors in the 2 groups (crowding and no crowding),and undoubtedly there were significant differences betweenthe groups.

In my opinion, the variation of lateral incisors should bea grouping agent, with all patients with variations in lateral in-cisors forming the experimental sample; then we could inves-tigate the difference of BDC in the 2 groups. This might betteranwer the question.

Wang JingXi’an, China

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doi:10.1016/j.ajodo.2009.09.010