Questions & Answers

Questions & Answers

QUESTIONS & ANSW ERS th e solution toward th e nerve tru n k is sug­ gested, and an incom plete block o f th e nerve may occur unless th e anesthetic...

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th e solution toward th e nerve tru n k is sug­ gested, and an incom plete block o f th e nerve may occur unless th e anesthetic agent or th e concentration of th e solution is strong enough to compensate fo r th is discrepancy.—Edward J. Driscoll, DDS, Oral M edicine and Surgery Branch, Na­ tio n a l In s titu te o f Dental Research, Na­ tio n a l In stitu te s o f Health, Bethesda, Md 20014.

Fissures Readers are invited to su b m it questions to The Journal's Questions and Answers section. Answers provided by experts are sent to questioners in advance of publication. Questions should relate to the a rt and science of dentistry.

A n esth esia

Q. A successful mandibular nerve block has been performed both on the inferior alveolar and the long buc­ cal nerves with the patient under lo­ cal anesthesia, and normal anesthesia of the lower quadrant has been achieved. There is a minor periapical abscess on one of the lower premolar teeth in the same quadrant. Why will the patient feel pain in this abscessed tooth when it is ex­ tracted although the nerve trunks to the tooth have been successfully blocked at a point about 2 inches away? Although a low pH in a region of infection can neutralize the local anesthesia, this is a situation in which the local anesthesia has been placed at a point some distance from the lo­ calized periapical abscess. What ac­ counts for this? A.

There is no lite ra tu re or te x t refer­ ence w hich precisely answers th is inter­ esting, c lin ic a l question. Incom plete anes­ thesia a fte r a nerve block occurred rather fre q u e n tly when procaine was the only lo­


cal anesthetic available. Since stronger so lutions o f procaine (4% ) and stronger drugs (lidocaine) have been used, incom ­ plete anesthesia rarely occurs. T his is true even in the te st o f local anesthesia fo r dental purposes, ie, removal of an in ­ flam ed pulp. If a nerve block is successful, there is a com plete break in th e a ffe re n t pathways, and th e pa tie nt can feel no pain; there­ fore, in th e situ a tio n described, there m ust be e ith e r an incom plete block or pain is carried by pathways other than the f ifth nerve, fo r example, by the cuta­ neous branches of cervical sensory nerves. Although both explanations áre possible, the fir s t would probably occur. In an in­ com plete block, when th e solution has been placed at some distance from the c ritic a l anatom ic region and has only in­ filtra te d th e region, it is possible to see signs o f fifth nerve anesthesia on th e lip, tongue, and gingiva w ith o u t obtaining c lin ic a l anesthesia. In the second explana­ tio n , th e outerm ost fibers, but not all the centerm ost fibers, o f th e nerve tru n k are anesthetized. When the solution has been placed in the exact anatom ic region, the signs of anesthesia are instantaneous. However, when 3 to 5 m in ute s or more elapse be­ fore th e signs appear, an in filtra tio n of

Q. I have a female patient about 25 years of age with pronounced Assur­ ing of long duration at the corner of the mouth. Her physician has not been able to cure this condition. She has complete dentures but, because her bite is closed, I am constructing new dentures. What other treatment for these fissures should I consider? ----- L A W R E N C E V. P E T E R S O N , D D S , Ait­ kin, Minn. 56431. A.

Vitam in B com plex d eficiency and perleche should be considered in relation to fissu ring a t th e corners o f th e mouth. A lthough rib ofla vin is th e sp e cific v ita ­ m in B fa cto r associated w ith fissuring, human beings usually do not show single B com plex fa cto r deficiencies. One would also expect other oral signs such as g lo ssitis w ith atrophy o f th e pa­ p illa e and redness and cheilosis. Thera­ p eutic doses of vita m in B com plex given over several weeks should be used if die­ ta ry analysis indicates such deficiency. Perleche may be associated w ith lock­ ing the lips or w ith saliva accum ulating at th e corners of th e mouth. This condi­ tio n is an in fe ctio n w ith Candida albicans and bacteria. Fungicides should be ap­ plied locally. Loss of interdental dim ensions is prob­ ably an im p orta n t fa cto r in your patient, and th is fa cto r should be corrected. If th e fissu rin g persists, th e vita m in d e fi­ ciency or perleche should be considered since there may be more than one cause fo r th e fissu ring .—H. B.G. Robinson, DDS, Dean, U niversity o f M issouri at Kansas City, Dental School, Kansas City, Mo.