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ePaper created 2014-11-07, 14:16:52 | version 1.30.01
I research gained resorbed after eight months, especially in the grafted bone outside the contours. 3) Overextensionofthebonegraftisnotaprophy- lactic measure against resorption: the greater the overextension of the grafted area, the greater the resorption. 4) The location of the grafted area appears to have an influence on the intensity of resorption. Max- imumresorptionofthegraftedbonefourmonths after surgery was found in the anterior region of the mandible, followed by the posterior region. Thisphenomenoncanbeexplainedbymuscleac- tivity. 5) The type of flap and use of the tunnel technique for grafting procedures appear to reduce the amountofboneresorption.Thiscanbeexplained by the influence of periosteal integrity on osteo- clast activity. _Nerve injury Trauma to the inferior alveolar nerve during im- plant placement may lead to loss of or altered sen- sation (paraesthesia) or to painful symptoms (dysaesthesia). Numerous unpleasant sensations may be described by the patient, including numb- ness, a crawling feeling, constant or periodic sharp pain, itching, tingling, hypersensitivity and burn- ing, throbbing, pins and needles, prickling, and warmth or cold. In implant dentistry, these sensa- tions often affect the lower lip, chin and the lower anterior gingiva. Rarely, the tongue may also have an altered sensation. Patients with tongue symp- tomssufferalossoftaste.AccordingtoGirardetal., the inferior alveolar nerve may have the potential forrecoveryuptotwoyearsafterinjury.20 However, Sunderland estimates that 75–90% of distal nerve atrophies are irreparable after one year of altered feeling.21 Classificationofnerveinjuries 1) Neurapraxia: neurapraxia is a mild injury caused by compression injury to the nerve or retraction ofthenerve.Examplesofcompressioninjuriesin- clude – pressurefromsalineorbloodfromtheimplant site while the implant is being screwed into position; – post-operative bleeding within the bone or around the mental foramen; – animplantinsertedintothemandibularcanal; – a piece of bone that invaded the canal during site preparation or implant insertion; and – a tie-back suture on the facial or lingual flap. In neurapraxia, there is no axonal degeneration distal to the point of the nerve injury, but there is a temporary conduction block during nerve recovery. Spontaneous recovery of the altered sensations most often occurs weeks after this type of injury. When the patient presents with symptoms of a nerveinjurywithintwodaysofsurgery,anoraldose of a corticosteroid (e.g. Decadron 8 mg) decreases inflammationandswellingintheregion.Ifthenerve trunkiscompressedorretractedduringsurgerybe- yond the usual protocol, the intravenous form of a corticosteroid (e.g. 1–2 mm of Decadron 4 mg/ml) may be applied (not injected) to the injured area for 1–2 minutes. This direct application will decrease the risk of Nissl body disintegration, which the causes the paresthesia.22 2) Axonotmesis: axonotmesis is a nerve injury with loss of axonal continuity but with the general structure of the nerve remaining intact (the en- doneurium is preserved). These injuries are more significantandmayresultindysaesthesiaorless- than-normal nerve recovery. Examples of ax- onotmesis injuries include 20 I implants3_2014 Fig. 15 Fig. 16a Fig. 16b Fig. 17a Fig. 17b Fig. 18a Fig. 18b Fig. 19a