ACCURACY OF DIGITAL LIGHT PROCESSING VERSUS
EGYPTIANDENTAL JOURNALVol. 64, 3245:3255, October, 2018I.S.S.N 0070-9484Oral Surgerywww.eda-egypt.org Codex : 207/1810ACCURACY OF DIGITAL LIGHT PROCESSING VERSUSSELECTIVE LASER SINTERING SURGICAL-TEMPLATES FORALL-ON-FOUR TECHNIQUE OF COMPUTER GUIDED DENTALIMPLANT PLACEMENT IN THE MANDIBLE: A PROSPECTIVEDOUBLE BLIND RANDOMIZED CLINICAL TRIALRehab T. Elsharkawy*, Eatemad R Taha**, Ahmed T. Elsharkawy*** and Ahmed A Hassan****ABSTRACTPurpose: Success and safety of dental implants requires accurate treatment planning andprecise implant placement. There should be no deviation between the virtually planned implantposition and the actual implant position after the implant installation regardless the technique ofconstruction of the surgical-guide. So this study was to evaluate and compare the accuracy of twodifferent CAD/CAM surgical guides in placement of all-on-4 implants. Materials and methods:A prospective randomized controlled double blind clinical study was carried out, in which twentyfour implants were placed in 6 edentulous patients. Patients were randomly allocated into one of thetwo groups: control group where surgeries were done using digital light processing (DLP) surgicalguides and study group where implants were placed using selective laser sintering (SLS) surgicalguides. Each patient received 4 implants in the anterior part of the mandible, 2 axial implants in thecenter and 2 tilted implants at the distal ends. CBCT were taken to the implants after the surgery andthe actual implant positions were compared to the planned implant position. The deviation betweenthe planned and actual implant positions were compared between the 2 techniques of surgical guideconstructions. Results: The results of comparison between the two groups showed a statisticallysignificant difference for all comparisons, with the SLS fabricated guides showing higher deviationfrom control than those fabricated by the DLP printer.Conclusion: Although the computer manufactured surgical guides simplifies surgery and helpin optimal implant placement, there is still evidence of degree of deviation from the planned implantspositions in both of the surgical guides, particularly the SLS fabricated guides so a safety zone so asafety zone is recommended during planning to avoid to avoid critical anatomical structures.KEY WORDS: All-on-four, tilted implants, implant placement, immediate loading, 3D printedsurgical guide, Laser sintered surgical guide.*Assistant Professor, Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Cairo University. Egypt**Assistant Professor, Department of Removable Prosthodontics, Faculty of Oral and Dental Medicine, AhramCanadian University. Egypt.***Lecturer of Oral and Maxillofacial Surgery, Faculty of Dentistry, Cairo University. Egypt.**** Assistant Lecturer, Department of Oral Radiology, Faculty of Dentistry, Fayoum University. Egypt.
(3246)E.D.J. Vol. 64, No. 4INTRODUCTIONRehabilitation of edentulous mandible couldbe carried out through several prosthetic treatmentoptions: complete dentures, removable implantretained prostheses, or fixed implant-supportedprostheses. However, implant retained or fixedimplant-supported prostheses provide a higherdegree of patient satisfaction and better quality oflife than removable prostheses. 1-3The problem exists when trying to placeimplants in patients with severely atrophic posteriorjaw. These cases require extensive surgical boneaugmentation with multiple surgical procedures toplace the implants. These surgeries require longertreatment time with high cost. The “All-on-4 “treatment concept developed by Paulo Malo is aspecific surgical and prosthetic treatment protocolthat allows the rehabilitation of edentulous jawswith cost-effective, graft-less solution that providesthe patient with an immediately-loaded, fixed, fullarch restoration on the day of surgery. The principleof this concept is to provide patients with fullarch restoration with only four dental implants inthe anterior part of edentulous jaws. Two straightanterior implants and two posterior implants tiltedup to 45 . Tilting the posterior implants enablesus to avoid the mental foramen and place longerimplants that provide better bone anchorage. Theimplants’ platform in this case is placed in moreposterior position which shortens the cantilever armand improves the inter implant distance. 4-6In dental implants surgical placement generallyand in the all-on-4 technique particularly, accuracyin treatment planning and precise implementationof this plan is vital for the functional and estheticoutcome as well as for the protection of vitalstructures and for predictable prosthetic results.Surgical guides play an important role in transferringthe treatment plan to reality during implant placementsurgery. It is well documented that dental implantsplaced using a surgical guide are more accuratelyRehab T. Elsharkawy, et al.positioned than those placed without a guide due toreduction of the possible human errors that mightoccur during free hand implant installation.7-8Guides for completely edentulous jaws are eithermucosa or bone supported. Mucosa supportedguides have additional advantage as they don’trequire tissue reflection. The flapless surgery, usingpunch technique only, makes the surgical procedureeasier with less postoperative pain and edema andit is faster in healing. While bone supported guidesrequire raising a flap to place the guide on thealveolar crest. It provides a good view to implantsites so it is commonly used when edentulous sitespossess thin bone.8,9 Recently, cone beam computedtomography (CBCT) has been introduced for presurgical implant planning. The use of computeraided design/computer-aided manufacturing (CAD/CAM) surgical guides serves to transfer the virtualplanning to the clinical procedure. The CAD/CAMsurgical guides enhances the precision of implantplacement, shortens operation time and lessens therate of complications compared to conventionallyconstructed guides.10The accuracy of implant placement using CAD/CAM surgical guides versus conventional guideswas compared in an in-vitro study, where theaverage differences between the planned and actualentry points in the mesio-distal and bucco-lingualdirections were measured. It was concluded that,accuracy of implant placement was improved usingan innovative CAD/CAM surgical template.11The CAD/CAM surgical guides are dependenton one of the two main technologies: eithersubtractive manufacturing technology or additivemanufacturing technology. First, the subtractivemanufacturing depends on milling technologiesto manufacture the final product from a block ofmaterial. However, the additive manufacturinginclude various methods as stereolithography (SLA),which uses UV light or laser beam to selectivelyharden layers of a liquid resin bath to produce the
ACCURACY OF DIGITAL LIGHT PROCESSING VERSUS SELECTIVE LASERsurgical guide. The second method is the digitallight processing (DLP) where a liquid polymeris exposed to light from a digital light processingprojector, which hardens the polymer layer by layeruntil the surgical guide is built. The third methodis the fused deposition modeling (FDM), wherea liquefied material is extruded through a nozzleand selectively deposited onto a platform layer bylayer. The fourth method is known as selective lasersintering (SLS) that uses a powder bed instead of aresin bath to manufacture the guide. A high powerlaser beam is directed to melt a fine layer of powder.After scanning of each cross section, the powderbed is lowered by one layer thickness and a newlayer of material is applied on the top, the processis repeated until the guide is completed. Variousmethods of manufacturing allow the transfer of theplanned surgery data with great precision; howeversome deviation from the virtual planning may bereported. 12-15The influence of surgical management onthe accuracy of implants inserted using mucosasupported surgical guide was evaluated usingstereolithographic template in a recent study. Theyfound that fixation of the surgical guide improvedits accuracy and resulted in better precision ofimplant placement.16 A comparison of accuracy ofsurgical templates fabricated by milling and rapidprototyping production methods was examinedin a previous study. Results showed that a vectormilled surgical guide had significantly smallerdeviations than did RP produced template. 17 Furtherinvestigations on the accuracy of rapid prototypingproduced guides were carried out using selectivelaser sintering surgical guides in flapless implantplacement. They reported some lateral and angulardeviation from the virtual planning. In addition41.67% of the implants had apical deviation.18In another study Sommacal et al, compared thefused filament fabrication (FFF) 3D printer to theprofessional digital light processing (DLP) printer(3247)for the fabrication of surgical guides for dentalimplant surgery. They found that the accuracy ofmanufactured guides is strongly dependent on theprinting device and method. They also added thatthe consumer 3D FFF printer is not suitable forthe fabrication of templates for guided implantsurgery.19Based on the limited researches available, theaccuracy of surgical guide produced by DLP & lasersintering surgical guides is still questionable. Thus,the present study was conducted to evaluate andcompare accuracy of DLP and the selective lasersintering surgical guides in all on four treatmentoptions for edentulous mandible.MATERIALS AND METHODSTwenty four implants were placed in six malepatients, with an age range between 58 to 67 years,who required fixed prosthodontic rehabilitation oftheir lower edentulous ridge. Patients were selectedfrom the outpatient clinic of Ahram CanadianUniversity (ACU). Only cases with proper ridgewidth that is at least 6 mm and sufficient bone heightthat is at least 14 mm in the anterior mandibularsegment, and adequate inter-arch distance, that is atleast 22 mm, were included in the study. Patientswith flappy tissues, history of recent extractions,with any pathologic conditions in the mandible,with limited mouth opening were excluded fromthe study. Patients who are smokers, or underradiotherapy or chemotherapy or bisphosphonatemedications, or having any uncontrolled systemicdisease that might affect the surgery in general orimplant placement or osseo-integration in particularwere also excluded. Participants were informedabout the nature of the study and were asked to signan informed consent form.Preoperative preparations: Patients weresubmitted to Cone Beam Computer Tomographyscans (CBCT) where a scanning appliance wascreated for each patient to use during the CBCT
(3248)E.D.J. Vol. 64, No. 4Rehab T. Elsharkawy, et al.scan. All patients were planned for mucosasupported surgical guides, so they were summitedto dual scan protocol. CBCT images were acquiredusing a Next Generation i-CAT scanner (ImagingSciences International, Inc., Hatfield, USA). Ascout view was obtained and adjustments weremade to ensure that patient was correctly alignedin the scanner according to adjustment light beambefore acquisition. The machine is supplied withAmorphous Silicon Flat Panel Sensor with CesiumIodide (CsI) scintillator, 0.5mm focal spot size,14 Bit gray scale resolution, and operating at thefollowing protocol for all the scans of the study:Tube voltage was 120 kVp, Milliampere was 37.07mAs, Voxel size was 0.250 mm, Scanning time was26.9 seconds, Exposure time was 7 seconds, andfinally the Field of view was 6 cm Height * 16 cmDiameter. Patients’ CBCT and scan appliance datawere merged at the planning software (NemoScan,Nemotec, Spain). Afterwards the virtual implantplanning was made using the CMI IS implants(NeoBiotech Co, Seoul, Korea) with 2 axial implantsin the center and 2 tilted implants at the distal ends(fig. 1). The distal implants were planned to be placeat 30 angle to the crest of the ridge to accept SCRPmulti abutment (NeoBiotech Co, Seoul, Korea).The design of surgical guide was then finalizedand the STL file was exported for 3D printing(fig. 2). Patients were randomly allocated into oneof the two groups: study group in which implantswere placed using selective laser sintering (SLS)surgical-guides constructed through Laser sintering3D printer (EOS-FORMIGA 1000, Germany) andcontrol group in which surgeries were done usingdigital light processing (DLP) surgical-guidesprinted by DLP 3D printer (Form 2, FORMLABS,USA). After acquiring the surgical guides fromprinters, finishing and installation of the metalsleeves was carried out. The sample randomizationwas achieved by the aid of a computer generatedrandomization table. All work was conducted inaccordance with the Declaration of Helsinki 1975,as revised in 2000.Fig. (1) Restoration driven virtual implant planning.Fig. (2) STL of CAD surgical guide ready for exporting to 3Dprinting.Surgical phase: One hour before the surgerypatients were given 2 g oral amoxicillin (Amoxil,Kahira Pharm. and Chem. Ind. Co., Egypt). Beforethe surgery patients were also asked to rinse themouth for one minute using chlorohexidine mouthwash (Hexitol, The Arab Drug Company ADCO,Cairo, Egypt). All surgeries were performed by thesame operator under complete aseptic conditions.All patients were locally anesthetized wherebilateral inferior alveolar and lingual nerve blocksanesthesia were used. The surgical guide wasinserted inside the patient’s mouth (fig.3); the punchwas used, through the preplanned holes in the guide,to cut gingiva on the crest of the ridge expose theplanned osteotomy sites. Then the surgical guidewas removed and the gingival discs were separatedby mucoperiosteal elevator. The surgical guidewas placed back and fixed in position by fixationscrews (fig.4). The osteotomy sites were prepared,through the planned locations and angulations of thesurgical guides, using drills of the 3DDX universal
ACCURACY OF DIGITAL LIGHT PROCESSING VERSUS SELECTIVE LASER(3249)kit (3 DDX, Boston, USA) running with 1300 rpmspeed using Surgical motor (Implantmed drive unit,W&H Dentalwerk, Bürmoos Salzburg, Austria)and 20:1 surgical contra angle hand-piece (W&HDentalwerk, Bürmoos Salzburg, Austria) undercopious irrigation. After the last drill, 4 implants(NeoBiotech Co., Seoul, Korea) were screweddown the osteotomy sites through the surgical guideusing the Neobiotech surgical kit. Two anterioraxial implants were tightened manually to 35N/cmand two posterior tilted implants were tightenedat 30 N/cm. Finally cover screws were tightened(10 N/cm) to the implants and the surgical guideswere removed. Patients were given postoperativeinstructions and medications as follows, amoxicillin500 mg Capsules, diclofenac Potassium 50 mgtab (Cataflam, Novartis Pharma S.A.E. Cairo,Egypt) , each of them every 8 hours for 5 days andChlorohexidine mouth wash twice daily for 7 days.Fig. (3) A case from the control group, DLP surgical guide inplace before soft tissue removal by the punch.Fig. (4) A case from the study group, SLS surgical guide fixedin place by the screws.Fig. (5) Superimposition of postoperative Scan overpreoperative planning for accuracy assessment.Fig. (6) Assessment of difference between virtual plan and realimplant positions in multiple views.After the surgery, patients were submittedto CBCT scan using the same parameter as thepreoperative scan. And the data of the postoperativescan was superimposed over the preoperative planto assess the accuracy of the implant placementusing the software (figs.5 and 6). Assessors in thisstudy were blinded regarding the type of guide usedin each case. Finally measurements were recordedand tabulated for statistical analysis.
(3250)E.D.J. Vol. 64, No. 4Prosthetic phase: The patients were recalledafter one week and primary alginate impressionswere made for the lower arch. Study models werepoured for construction of lower custom tray witha window cut over the implants. The coveringscrews were removed and the octa-abutments wereattached to the implant fixtures, then the impressiontransfer copings were screwed to the octa abutmentsusing long fixation screws. Acrylic resin rods waspremade on the study casts to splint the impressioncopings together. They were fixed in place in thepatient s mouth using duralay self-care acrylic resin(Reliance, IL, USA). Impression was registeredin polyether material using an open tray splintedtechnique. Master casts were fabricated using extrahard stone type IV and the implant analogues werefixed in their specific position inside the casts.Wax patterns were fabricated on the master caststo be casted into metal frameworks. Each metalframework was tried in the patients’ mouth to assurepassive fit. (fig. 7).A wax rim was built over the metal frameworkand the vertical dimension and bite registration weretaken. The models were then mounted on semiadjustable articulator and the teeth set up was done,following the lingualized occlusal concept ensuringthere is no interference with jaw movements intoeccentric position, then tried in the patient’s mouth.The final restoration was made with acrylic teethand screwed in to the implants’ abutments (fig. 8).Fig. (7) Metal Framework during trial in patient’s MouthRehab T. Elsharkawy, et al.Fig. (8) Final prosthesis in place.RESULTSIn this study twenty four implants were placedin six patients without any complications. Twelveimplants in three patients were placed through theSLS-3D CAD/CAM surgical guide and the other 12implants were placed in three patients through DLP3D CAD/CAM surgical guide. All patients weremales, ranging in age between 58 and 67 years withmean age 62. All patients completed the follow upand the prosthetic phase till end of the study with noattrition of the sample.After the surgery, patients were submitted toCBCT scan and the data of the postoperative scanwas superimposed over the preoperative plan toassess the accuracy of the implant placement.Accuracy of the implant placement was assessedby measuring global distance between the virtualimplant and real implant. crestal platform, globaldistance between virtual implant and real implantapex, and angular deviation between the virtualimplant and real implant at mesio-distal and buccolingual aspectsFirst, there was a substantial intra-observeragreement of results for both the DLP and SLSsurgical guides’ results, with higher matching forSLS results (Table 1).
(3251)ACCURACY OF DIGITAL LIGHT PROCESSING VERSUS SELECTIVE LASERTABLE (1) Intra-observer agreement values for SLSdifference between the groups with a higherdeviation values for the SLS than DLP (F 29.871,P 0.001) (Table 2).and DLP resultsMeasurementof agreementAsymp. Std.ErrorNo of validimplantsSLS0.726*0.08112DLP0.659*0.08812The results of pairwise comparison for thecontrol and test groups using Tukey’s HSD pairwisecomparison of means* also showed a statisticallysignificant difference for all comparison with theSLS showing higher deviation from control thanDLP (Table 3).*( 0) Poor agreement, (0.0 – 0.20) Slight agreement,(0.21 – 0.40) Fair agreement, (0.41 – 0.60) Moderateagreement, (0.61 – 0.80) Substantial agreement, (0.81 –1.00) Almost perfect agreementSecond, at the apical level, again, there wasa statistically significant difference between thegroups with a higher deviation values for the SLSthan DLP (F 43.890, P 0.001) (Table 4).Regarding the Horizontal deviation: first atthe crestal level the results of comparison betweenthe control, SLS and DLP showed a significantTABLE (2) Mean values of crestal deviation for SLS and here SD standard deviation, SEM standard error of meanTABLE (3) Pairwise comparison of control, SLS and DLP for crestal deviationComparisonDiff. of MeansSLS vs. DLP0.319DLP vs. ControlSLS vs. ControlqP1.287.037 0.001*1.610.731 0.001*2.690.01**: significant at P 0.05; P 0.05 (non-significant), P 0.05(significant), and P 0.01 (highly significant).TABLE (4) Mean values of apical deviation for SLS and .23Where SD standard deviation, SEM standard error of mean* Tukey’s HSD (honestly significant difference) test, is a single-step multiple comparison procedure used in conjunctionwith an ANOVA to find means that are significantly different from each other
(3252)E.D.J. Vol. 64, No. 4Rehab T. Elsharkawy, et al.The results of pairwise comparison for thecontrol and test groups using Tukey’s HSD pairwisecomparison of means showed a statisticallysignificant difference for all comparison groupsexcept DLP versus SLS (P 0.085), with the SLSshowing higher deviation from control than DLP(Table 5).comparison of means showed a statisticallysignificant difference for comparison except SLSversus FDM (P 0.055). SLS is showing higherdeviation from control than DLP (Table 7).Then for the Angle Deviation B (CoronalPlane), there was a statistically significant differencebetween the groups with a higher deviation valuesfor the SLS than DLP (F 77.692, P 0.001)(Table 8).Now regarding the Angle deviation, it wasmeasured at sagittal plan and at coronal plan. Firstfor the Angle Deviation A (Sagittal plane),there wasa statistically significant difference between thegroups with a higher deviation values for the SLSthan DLP (F 57.071, P 0.001) (Table 6).The results of pairwise comparison for thecontrol and test groups using Tukey’s HSD pairwisecomparison of means showed a statisticallysignificant difference for all comparison with theSLS showing higher deviation from control thanDLP (Table 9).The results of pairwise comparison for thecontrol and test groups using Tukey’s HSD pairwiseTABLE (5) Pairwise comparison of control, SLS and DLP for apical deviationComparisonDiff of MeansqPDLP vs. Control1.637.716 0.001*SLS vs. DLP0.31.7860.085*SLS vs. Control1.9315.46 0.001**: significant at P 0.05; P 0.05(non-significant), P 0.05(significant), and P 0.01 (highly significant).TABLE (6) Mean values of angle deviation A for SLS and 8.64Where SD standard deviation, SEM standard error of meanTABLE (7) Pairwise comparison of control, SLS and DLP for angle deviation AComparisonDiff of MeansqPDLP vs. Control3.8579.052 0.001*SLS vs. DLP1.1120.055SLS vs. Control4.97610.77 0.001**: significant at P 0.05; P 0.05(non-significant), P 0.05(significant), and P 0.01 (highly significant).
(3253)ACCURACY OF DIGITAL LIGHT PROCESSING VERSUS SELECTIVE LASERTABLE (8) Mean values of angle deviation B for SLS and here SD standard deviation, SEM standard error of meanTABLE (9) Pairwise comparison of control, SLS andDLP for angle deviation BComparisonDiff ofMeansqPDLP vs. Control2.9910.58 0.001*SLS vs. DLP1.673.310.002SLS vs. Control4.6712.321 0.001**: significant at P 0.05; P 0.05(non-significant),P 0.05(significant), and P 0.01 (highly significant).Within group comparison for deviation fromcontrolSLS and DLP showed a statistically significantdifference between the measured deviation at thecrest and angle deviation B (F 29.871, P 0.001F 77.692, P 0.001for SLS and DLP respectively).TABLE (10) Mean values of measured deviations forSLS and DLPSLSDLPMeanSDMeanSDHorizontal Crestal Deviation1.60.5621.280.326Horizontal Apical Deviation1.930.6841.630.502Angle Deviation A4.976 2.5293.8572.333Angle Deviation B4.672.991.552.07Fig. (8) Bar chart showing mean values of measured deviationsfor SLS (blue) and DLP (red).DISCUSSIONIdeal implant placement enhances theestablishment of favorable forces on the implantsand the prosthetic component. In this sense, CAD/CAM surgical guides were utilized in this study toachieve better prosthetic results.20,21In this study, twenty four implants were installedin six patients without any complications, usingmucosa supported DLP and SLS surgical guides. Allsurgical guides were placed and fixed in position byfixation screws to improve its accuracy and allowfor better precision of implant placement.The results of this study reported some deviationsfrom the virtual planning in the two studied groupswith statistically significant difference (as P 0.05).Many authors have reported deviations in theirclinical in-vivo studies between the postoperative
(3254)E.D.J. Vol. 64, No. 4position and the preoperative plan.16,22,23 Some ofthem attributed this finding to the variation in thethickness of mucosa at the implant insertion site.They observed a significant correlation betweenmucosa thickness and the degree of deviation asit affects the accurate positioning as well as thestability of the guide.22 In addition precision ofmuco-supported surgical guides with and withoutfixation screws in the edentulous ridges wasevaluated by Cassetta et al,2014 and they showedthat the fixed guides resulted in better precisionof implant placement, which was statisticallysignificant for angular deviation.16 Other authorsreferred this deviation to the bone structure itself.They reported a more pronounced deviations in thedental implants position, when the jaw bone hadlower resistance to torque (mostly medullary as thatof maxilla), compared to compact bone.16,23Regarding the horizontal deviation, the meanapical deviation values for the two studied groupswere higher than that at the crestal region (it was1.63 and 1.93 for DLP and SLS respectively at theapical region, while it was 1.28 and 1.6 at the crestalregion). This finding was in accordance with D’haeseet al, 2012 and Vieira et al, 2013, who reportedgreater deviation at the apex of the implants. Theyhave argued that apical deviations are dependent onmucosal thickness and morphological type of bonestructure 22,23However, the mean of angular deviation valuesfor the two studied groups in this study (3.85 and4.97 for DLP and SLS respectively at the sagittalplane, while it was 2.99 and 4.67 for DLP and SLSrespectively at the coronal plane) were higher thanthat reported by Pettersson et al who reported anangular deviations of 1.93 that represent greateraccuracy of implant placement. 24 On the otherhand, angular deviation less than 5 was recorded byErsoy et al, 2008, which is similar to the deviationreported in our study.Rehab T. Elsharkawy, et al.The results of comparison between the twogroups showed a statistically significant differencefor all comparison with the SLS showing higherdeviation from control than DLP. This findingwas supported by another clinical study that madeto evaluate the accuracy using selective lasersintering surgical guides for flapless dental implantplacement and immediate definitive prosthesisinstallation. They reported a mean angular coronaland apical deviations of 6.53 , 1.35 mm and 1.79mm, respectively. Thus they concluded that thecomputer‑aided dental implant surgery still requiresimprovement and should be considered to be in thedevelopmental stage.18 Therefore; we recommend asafety zone of at least 2 mm is necessary to avoidcritical anatomical structures.REFERENCES1.Att W, Bernhart J, Strub JR. Fixed rehabilitation of theedentulous maxilla: possibilities and clinical outcome. JOral Maxillofac Surg, 2009; 67:60–73.2.Att W, Stappert C. Implant therapy to improve quality oflife. Quintessence Int 2003; 34:573–581.3.Guckes AD, Scurria MS, Shugars DA. A conceptualframework for understanding outcomes of oral implanttherapy. J Prosthet Dent 1996; 75:633–639.4.P. Maló, M. De Araujo Nobre, A. Lopes, A. Ferro, and I.Gravito, “All-on-4 treatment concept for the rehabilitationof the completely edentulous mandible: a 7 year clinicaland 5 year radiographic retrospective case series withrisk assessment for implant failure and marginal bonelevel,” Clinical Implant Dentistry and Related Research,2015; 17, : 531–5415.Malo P, Rangert B, Nobre M. “All-on-Four” immediatefunction concept with Branemark System implants forcompletely edentulous mandibles: a retrospective clinicalstudy. Clin Implant Dent Relat Res 2003; 5 (1): 2–9.6.Ho Christopher Ck. Implant rehabilitation in the edentulousjaw: The “All-on-4 concept” immediate function.Australian dental practice 2012; 23 (2): 138–148.7.Windhorn RJ. Fabrication and use of a simple implantplacement guide. Journal of Prosthetic Dentistry 2004;92(2): 196-199.
ACCURACY OF DIGITAL LIGHT PROCESSING VERSUS SELECTIVE LASER8.Umapathy T, Jayam C, Anila B S, Ashwini C P. Overviewof surgical guides for implant therapy. J Dent Implant2015; 1 (5): 48-52.9.Rosenfield AL, Mandelaris, GA and Tardieu, PB,Prosthetically directedimplant placement using computersoftware to ensure precise placement and predictableposterior outcomes. Part 3: stereolithographic drillingguides that donot require bone exposure and the immediatedelivery of teeth. Int J of Periodontics and RestorativeDentistry 26:493-49910. Widmann G, Bale RJ. Accuracy in computer-aided implantsurgery: A review. Int J Oral Maxillofac Implants. 2006;21:305–13.11. Nokar S, Moslehifard E, Bahman T, Bayanzadeh M,Nasirpouri F, Nokar A. Accuracy of implant placementusing a CAD/CAM surgical guide: An in vitro study. Int JOral Maxillofac Implants 2011;26:520-6.12. Geng, W, Liu C, Su Y, Li J, Zhou Y. Accuracy ofDifferent Types of Computer-Aided Design/computerAided Manufacturing Surgical Guides for Dental ImplantPlacement. Int J Clin Exp Med. 2015; 8(6): 8442-8449.13. Van Noort R, The future of dental devices is digital. DentMater 2012, 28 (1):3-12.14. Masri R. and Driscoll CF, Clinical applications of digitaldental technology.2015, John Wiley. Inc. pp, 41-5615. Ozan O, Turkyilmaz I, Ersoy AE, McGlumphy EA,Rosenstiel SF. Clinical accuracy of 3 different types ofcomputed tomography-derived stereolithographic surgicalguides in implant placement. J Oral Maxillofac Surg 2009;67:394–401.16. Cassetta M, Giansanti M, Di Mambro A, Stefanelli LV.Accuracy of positioning o
guides. Each patient received 4 implants in the anterior part of the mandible, 2 axial implants in the center and 2 tilted implants at the distal ends. CBCT were taken to the implants after the surgery and the actual implant positions were compared to the planned
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most of the digital signal processing concepts have benn well developed for a long time, digital signal processing is still a relatively new methodology. Many digital signal processing concepts were derived from the analog signal processing field, so you will find a lot o f similarities between the digital and analog signal processing.
Digital image processing is the use of computer algorithms to perform image processing on digital images. As a subfield of digital signal processing, digital image processing has many advantages over analog image processing; it allows a much wider range of algorithms to be applied to the in
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Digital inclusion is defined in various ways and is often used interchangeably with terms such as digital skills, digital participation, digital competence, digital capability, digital engagement and digital literacy (Gann, 2019a). In their guide to digital inclusion for health and social care, NHS Digital (2019) describe digital
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