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ePaper created 2015-11-17, 15:11:47 | version 1.38.0
Volume 1 | Issue 1/2015 63Journal of Oral Science & Rehabilitation Vo lu me tr i c 3- D di gi tal analysi s Introduction A recent systematic review of the literature re- garding dimensional changes to the hard and soft tissue after tooth extraction was evaluated.1 A vertical hard-tissue loss of 11– 22% after six months of healing was found. When the combined hard- and soft-tissue di- mensionalchangeswere considered, avariation of +0.1 to -0.9 mm after six months and of +0.4 to -0.8 mm after 12 months was found. A hori- zontal dimensional reduction of the hard tissue of between 29% and 63% was observed six to seven months after tooth extraction. When the combined hard- and soft-tissue dimensional changes were considered, a loss of 1.3 mm after threemonthsandof5.1mmafter12monthswas found. Moreover, the reduction was more rapid during the first three to six months, followed by a minor gradual reduction in dimensions there- after. Inthat review,the methods ofmeasurement ofthedimensionalvariationbetweenthetimeof extraction and the subsequent period of re- analysis were also reported. For the hard tissue, radiographs, computed tomography scans, cone beam computed tomography scans, or re- entry surgical procedures that included stents orotherreferenceswere usedforthe analysis of the dimensional changes. For the combined hard- and soft-tissue dimensional changes, the casts mainlywere analyzed. Dimensionalchangestothealveolarprocess may be analyzed using digitalized images (meshes) obtained by various 3-D digital meth- ods: on casts, using laser scanners and struc- tured-light 3-D scanners,2 or chairside using 3- D intra-oralphotogrammetric systems.3 The re- producibility of these methods has been shown to be high and their use for analyzing dimen- sionalvariationsofthealveolarprocesshasbeen recommended.4–6 Many of the recent studies that have used 3-D systems to analyze dimen- sional variations of the alveolar process, how- ever, lost substantial information in transform- ing 3-D datato 2-D measurements.7, 8 Volumetric data instead were reported in a clinical study in which augmentation proce- dures were used at implants placed in edentu- lous ridges reduced in volume.9 In the study, a grid was superimposed on the images so that both the global difference in volume before and after treatment and the differences in specific areaswere reported. 2-D variations of the hard tissue around im- plants placed immediately into extraction sockets have been reported in clinical stud- ies,10, 11 and, in an animal study, combined hard- and soft-tissue 2-D changes have been analyzed.12 However, there is a lack of studies that report volumetric data on combined hard- and soft-tissue variation at implants placed immediately into extraction sockets in humans using a 3-D system. Hence,the aim ofthe pres- ent study was to validate the use of a novel method to elaborate 3-D data on dimensional changes to the alveolar process after one year of follow-up at implants placed immediately into extraction sockets. Materials&methods The research protocolwas approved bythe ethics committee ofAzienda Ospedaliera di Padova, De- partment of Neurosciences, University of Padua (protocol#2629P;10April2012). Patient selection In order to be recruited for the study, the pa- tientshadtomeetthefollowinginclusioncrite- ria: willing to participate for the duration of the studyandto provide informed consent, at least 18 years of age, in good general health, pres- enceofatoothtobeextracted,willingtoaccept the immediate placement of an implant into the extraction socket, and presence ofadjacent teeth both mesially and distally. The following exclusion criteria were adopted: pregnancy or untreated dental disease. Smoking status was recorded, but was not considered a contraindi- cationtotreatment. Patientswere advisedthat smoking is associated with an increased risk of implant failure. Ten consecutive subjects were recruited. Writtenconsentwasobtainedfromthepatients. All patients received a careful dental and peri- odontal examination, followed by oral hygiene instructions and dental and periodontal treat- ment, when necessary. All treatments and fol- low-upswere carried out in one clinic in Italybe- tweenSeptember2012andSeptember2014. An impression using polyvinyl siloxane (Sky PuttyandSkyLight,Sweden&Martina,DueCar- rare, Italy) was taken before tooth extraction (Time 0 = T0) and a gypsum cast was obtained (ORTOTYPO 4, LASCOD, Sesto Fiorentino, Italy).