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Dental Tribune Middle East & Africa No. 5, 2016

Dental Tribune Middle East & Africa Edition | 5/2016 implant tribune 3 ◊Page2 veolar bone and 1,320 and 1,560 HFU at the basal bone. The highest bone density in the maxilla was observed in the canine and premolar areas, and maxillary tuberosity showed the lowest bone density. Density of the cortical bone was greater in the mandible than in the maxilla and showed a progressive increase from theincisortotheretromolararea. D5, known as the sinus zone, is a bilateral zone of the alveolar ridge of posterior maxilla located at the base of the maxillary sinus from the second premolar to pterygoid plates. There are certain common features of replacement of missing tooth or teeth (rarely two premolars and commonly one or two molars) with dental implants in this zone. It often relates to the degree of sinus pneumatisation and vertical bone deficiency that may require supple- mental surgical procedures in the subantral area in order to place en- dosseousimplants. This bilateral maxillary posterior zone that extends from the second premolar to the pterygoid plates is located at the base of maxillary si- nuses (antra of Highmore). Embryo- logically, the hard palate and the alveolar process of the maxilla form the barrier between the maxillary sinus and the oral cavity. The bone heightbetweenthefloorofthemax- illary sinus and the alveolar crest is routinely analysed in oral implan- tology when posterior maxillary im- plantsarecontemplated.Anincrease of sinus volume or sinus pneumati- sation after a loss of posterior tooth/ teeth often necessitates vertical bone augmentation with a sinus lift procedure. The bone of this region is also known to have compromised bone quality (types 3 and 4) that can increase an implant failure rate. The main blood supply to the posterior maxilla derives from the posterior superior alveolar artery, the greater and lesser palatine arteries (all from the maxillary artery), the ascending pharyngeal branch of the external carotid artery, and the ascending palatine branch of the facial artery. An injury to the posterior superior alveolar artery during the lateral ap- proach for subantral augmentation can cause haemorrhage that may requirecoagulation. Materialsandmethod From a data base of 1,134 patients who had received 4,800 dental im- plants from 2001 till August 17th 2015, randomly a prosthodontist with no knowledge of these crite- ria was requested to select 100 files fromthedatabaseandpresentthem for this study. The 100 files had re- ceived panoramic and cone beam computed tomography (CBCT, Table 1) during their diagnostic visit. The average HFU of the randomly select- ed100caseswascalculated. Results Hounsfieldunit:Thedataintable#1, out of 100 samples, demonstrated that the average HFU was the mini- mum in D5 (213 HFU), and followed by D4 (528 HFU), D3 (561 HFU), D2 (599 HFU) and D1 (654 HFU) in as- cending order respectively (Fig. 1 and Table2). Discussion There are few literature reports that attempt to study implant location, among a multitude of other factors, to determine its influence on the success or failure of dental implant treatment. Becker et al. evaluated 282 implants placed in the maxillary andmandibularmolarpositionsina prospective study.34 The six-year cu- mulative success rate (CSR) for max- illaryposteriorimplantswas82.9per cent, for mandibular posterior, 91.5 per cent. He concluded that CSR in the posterior regions is lower than usually reported for anterior regions of the maxilla and mandible due to differences in bone quality and quantity. Eckert et al. assessed 1,170 endosseous implants placed in par- tially edentulous jaws in a retrospec- tive study: anterior maxilla, poste- rior maxilla, anterior mandible, and posterior mandible.35 In his report, the location of implants did not ap- pear to have any effect on implant survival, implant fracture rates, screw loosening, or screw fracture. Parein et al. analysed 392 consecu- tively placed Brånemark implants that were inserted in 152 partially edentulous posterior mandibles and restored with 56 crown and 168 bridge restorations in a long-term retrospective study.36 The CSR of all implants in the posterior mandible was89.0percentatsixyears. Fewer complications were found in implant prostheses located exclu- sively in the premolar region versus molar and mixed molar-premolar implant restorations. Drago investi- gated the location-related osseointe- grationof673implantsplacedin169 patients that were observed from seven months to eight years follow- ing occlusal loading.14 Implant osse- ointegration was 89.1 per cent in the anterior maxilla, 71.4 per cent in the posterior maxilla, 96.7 per cent in the anterior mandible, and 98.7 per cent in the posterior mandible. Moy et al. analysed implant failure rates and associated risk factors, observed implant failure of 8.16 per cent in the maxilla and 4.93 per cent in the mandible.37 Increased age (over 60) was strongly associated with the risk ofimplantfailure.Bassetal.,evaluat- ing 303 patients with 1,097 implants overathree-yearperiod,assessedthe success rate of implants in the max- illa at 93.4 per cent and 97.2 per cent in the mandible.38 Poor bone quality playedthemajorroleinimplantfail- ure with bone quantity demonstrat- inglessimportance. Allpresentedreportsappeartoagree that the CSR of dental implants is generally high and that implant lo- cation plays an important role in implant success. CSR of implants in the mandible seems to be slightly higher than in the maxilla—a differ- ence of about 4 per cent. The success rate of implants in the anterior re- gions seems to be higher than in the posterior regions of the jaws, mostly due to the quality of bone: about 12 per cent difference between anterior maxilla and posterior maxilla, and about 4 per cent difference between anterior mandible and posterior mandible. On the basis of reviewed literature reports, an implant treat- ment in the anterior mandible ap- pears to be the most successful. The posterior maxilla appears to be the leastsuccessfulregionofthejawsfor implantrehabilitation. Conclusion Thereisatrendofescalatinglevelsof HFUindifferentpartsoftheoralcav- ity. The highest being the anterior mandible, followed by the posterior maxilla,posteriormandible,anterior maxilla and posterior maxilla with sinus lift procedure respectively. Es- timated HFU can assist the surgical phase,asthenumberoftheancillary procedures can be pre-estimated according to different areas in the mouthduringthediagnosticphase. Fig1 Editorial note: A list of references is availablefromthepublisher. DrSouheilR.Hussaini,BDS,MS OralImplantologyMedicalCenter 204AlWahdaBuilding Port SaeedRd,Deira, POBox39695Dubai,UAE Tel.:+97142956595 Fax:+97142958757 souheilh@eim.ae www.ID-SC.com

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