Een vergelijking van objectieve en subjectieve parameters bij het immediate loading concept in de edentate kaak

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1 Academiejaar Een vergelijking van objectieve en subjectieve parameters bij het immediate loading concept in de edentate kaak Filip Martens Promotor: Prof. dr. H. De Bruyn Masterproef voorgedragen in de Master na Master Opleiding Parodontologie

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3 Academiejaar Een vergelijking van objectieve en subjectieve parameters bij het immediate loading concept in de edentate kaak Filip Martens Promotor: Prof. dr. H. De Bruyn Masterproef voorgedragen in de Master na Master Opleiding Parodontologie

4 De auteur(s) en de promotor geven de toelating deze Masterproef voor consultatie beschikbaar te stellen en delen ervan te kopiëren voor persoonlijk gebruik. Elk ander gebruik valt onder de beperkingen van het auteursrecht, in het bijzonder met betrekking tot de verplichting uitdrukkelijk de bron te vermelden bij het aanhalen van resultaten uit deze Masterproef. Datum handtekening student handtekening promotor Filip Martens Prof. Dr. Hugo De Bruyn

5 Inhoudsopgave I. Abstract 1 II. Algemene Inleiding 3 III. Artikel 10 a. Introduction 11 b. Materials & Methods 12 c. Results 19 d. Discussion 30 IV. Samenvatting 34 V. Referentielijst 37

6 I. Abstract 1

7 The present prospective study evaluated clinical results of immediately loaded BIOMET 3i implants with different surface topographies. Thirty-three periodontally compromised patients received 163 implants (130 in the maxilla and 33 in the mandible; 104 NanoTite and 31 OSSEOTITE ). After a mean loading time of 57 months, the survival rate was 96.3%. Mean crestal bone loss was 1.6mm. No difference in bone loss was detected between the two surfaces. Only 6% of the implants were detected with peri-implantitis based on total bone loss from the day of surgery of >2 mm and probing depths of >4 mm. Patient s satisfaction was evaluated using OHIP-14 questionnaire en VAS questions. An evaluation of the implant fixed complete denture by the dentist was registrated using the Californian Dental Index. Descriptive statistics were performed and it seems that patients were very satisfied with the immediate loading treatment after 5 years of function. The dentist rated the prothesis of acceptable quality in 86% of the cases. 2

8 II. Algemene Inleiding 3

9 Volledige of partiële protheses zorgen traditioneel voor tandvervanging en/of voor het vervangen van weke weefsels. Hiermee wordt getracht om het kauwvermogen, de spraak, de esthetiek en de levenskwaliteit van de patiënt te verbeteren. Deze manier van behandelen geeft dikwijls niet het resultaat dat een patiënt verwacht en deze patiënten opteren dan meestal voor een vaste oplossing. Het is echter niet altijd mogelijk om een vaste brugconstructie te plaatsen indien het aantal geschikte (1, 2) resterende gebitselementen onvoldoende is. In de vroege jaren 60 rapporteerde Per-Ingvar Bränemark de osseointegratie van een titanium implantaat in het alveolair bot. (3) Deze ontdekking was een grote stap in de evolutie van de tandheelkunde aangezien er een nieuwe mogelijkheid was om kauwfunctie en esthetiek te verbeteren. Sindsdien is orale rehabilitatie met behulp van implantaten onderwerp geweest van onderzoek en is er reeds veel literatuur gepubliceerd. Bij het orginele Bränemark protocol werd er twee-fasig gewerkt. Hierbij werd het implantaat subgingivaal geplaatst en tijdens een tweede fase vrijgelegd. In de onderkaak gebeurde dit na 3 maanden, in de bovenkaak na 6 maanden. (4) Deze genezingsperiode werd beschouwd als noodzakelijk om een goede osseointegratie te bekomen, maar was niet gebaseerd op wetenschappelijke evidentie. Men dacht dat de interpositie van weke weefsels nadelig was voor de genezing. Bij het vrijleggen van de implantaten werden abutments geplaatst en kon er gestart worden met de prothetische procedure. 4

10 Met de ontwikkeling van een nieuwe oppervlak en design van het implantaat, nieuwe chirurgische technieken, geavanceerde diagnostische middelen en planningshulpmiddelen begon men andere behandelsprotocollen toe te passen. Deze ontwikkeling zorgde voor een kortere behandelduur, het vermijden van een tweede chirurgie en het verlaagde de drempel voor de patiënten om voor een implantaat ingreep te kiezen. Verschillende studies hebben aangetoond dat een 1-fasig behandelprotocol net zo goede behandelresultaten had als het oorspronkelijk 2-fasige behandelprotocol indien aan bepaalde voorwaarden werd voldaan. (4-12) Osseointegratie werd origineel gedefinieerd als een rechtstreeks contact van bot met het oppervlak van een functioneel artificieel implantaat. Dit was gebaseerd op een lichtmicroscopische analyse. (12) Om een goede osseointegratie van het implantaat te bekomen is een goede primaire stabiliteit van groot belang. Een gebrek aan primaire stabiliteit kan te grote microbewegingen veroorzaken wat kan leiden tot non-integratie dankzij een incapsulatie met fibreus bindweefsel. De bewegingen ter hoogte van de bot-implant interface moeten onder een bepaalde drempelwaarde blijven. (13) Aangezien er in de bovenkaak meer spongieus bot is dan in de onderkaak is het hier moeilijker om een goede primaire stabiliteit te krijgen. Door het aanpassen van de chirurgische techniek zoals het onderpreparen van de osteotomie of het gebruik van bredere implantaten wordt getracht om ook in de bovenkaak een goede stabiliteit van het implantaat te bekomen. (14, 15) 5

11 In het algemeen werden uitneembare protheses gebruikt als tijdelijke oplossing tijdens de genezingsperiode. Veel patiënten vinden deze prothese oncomfortabel en het zou gunstig zijn mocht de genezingsperiode kunnen worden ingekort zonder het succes van de implantaat behandeling te compromiteren. Hedendaags is men er over eens dat vroege en onmiddellijke belasting gelijkaardige resultaten kunnen bieden als het klassieke protocol, waarbij de implantaten na 3-6 worden belast, indien aan bepaalde voorwaarden wordt voldaan. Op deze manier is men in staat om op kortere termijn de patiënten functioneel en esthetisch een oplossing te bieden. (16-19) Volgens een systematisch review van Henry et al. in 2008 (15) zijn er reeds meerdere definities gegeven aan het concept immediate loading. Verschillende auteurs raken er niet uit binnen welke tijdspanne de voorlopige prothetische voorziening moet worden geplaatst. Ondanks dat immediate normaal gezien onmiddellijk betekent, wordt een periode van 3 dagen geaccepteerd. Dit is ook noodzakelijk voor het tandtechnisch labo om de voorlopige voorziening te kunnen vervaardigen. In de huidige literatuur wordt de periode van 3 dagen algemeen aanvaard als zijnde immediate loading. Verschillende prospectieve studies rapporteerden overlevingswaarden die variëerden van 91,3-100% voor implantaten die onmiddellijk zijn belast met een voorlopige vaste brug in de edentate onderkaak. (20-32) Het succes van onmiddellijk belaste implantaten in de volledig edentate bovenkaak is minder beschreven dan deze in de onderkaak. De overlevingswaarden varieerden 6

12 hier van 88,5-100%. Deze lagere waarden zijn veelal te wijten aan de mindere botkwaliteit van de bovenkaak. (8, 20, 24, 25, 33-39) Sinds de ontdekking van osseointegratie door Brånemark zijn schroefvormige implantaten met relatief glad oppervlak op grote schaal gebruikt. Om de voorspelbaarheid van de behandeling met implantaten te verbeteren zijn er in de loop der tijd modificaties aan het implantaatoppervlak gebeurd. In de eerste plaats is men de implantaten gaan opruwen. Dit gebeurt meestal door zandstraling of door het implantaat te etsen. Door het opruwen vergroot de oppervlakte van de implantaten wat leidt tot een verhoogde bot-implant contactzone. Hierdoor was men in staat om hogere succes en overlevingswaarden te bekomen, voornamelijk wanneer de implantaten geplaatst zijn in bot met een lage densiteit. (40, 41) Nadien is men nanotechnologie gaan toepassen om de osteoconductiviteit van de implantaten te vergroten. (42) Een aantal klinische studies met beperkte opvolgingstijd hebben aangetoond dat implantaten voorzien van een nano-gecoated oppervlakte hogere (18, 43) succes waarden geven. Een deel van deze thesis is geaccepteerd als artikel dat de immediate belasting van BIOMET 3i implantaten (Palm Beach Gardens, Floride, USA) beschrijft in de edentate kaak. De belasting gebeurde met een voorlopige kunststofbrug binnen de 3 dagen na het plaatsen van de implantaten. Twee verschillende types implantaten werden gebruikt: NanoTite en OSSEOTITE. Het OSSEOTITE implantaat heeft een dubbel geëtst (dual acid etched) titaniumoppervlak. Het NanoTite implantaat heeft hetzelfde dubbel geëtste oppervlak, maar heeft een kristallijne bedekking van calciumfosfaat nanopartikels als oppervlaktecoating. Theoretisch zou het bio-actieve 7

13 oppervlak, dat de initiële cascade van osseointegratie zou versnellen, leiden tot een hoger implantaatsucces. (34) Een aantal studies tonen aan dat het gebruik van gemodificeerde implantaatoppervlakken goede resultaten geeft bij immediate loading. (18, 34) Tot op vandaag is er slechts beperkte literatuur beschikbaar over de tevredenheid van patiënten met een implantaatbehandeling. Dit geldt dan ook voor de tevredenheid bij de onmiddellijke belasting met een volledige brug. In een studie van Erkapers et al (44) werd patiëntentevredenheid bij onmiddellijke belasting met een volledige brug in de bovenkaak geëvalueerd bij 51 patiënten. De OHIP-49 vragenlijst werd gebruikt en er werd aangetoond dat er psychisch, fysisch, sociaal en psychologisch een significante verbetering optrad. (45) Dierens et al (44) evalueerden de subjectieve opinie van patiënten die behandeld zijn met onmiddellijke belasting bij een volledige boven of onderkaak tot 1 jaar postoperatief. Het comfort en de esthetiek verbeterden volgens de patiënt significant binnen de week na chirurgie en onmiddellijke belasting. Na het plaatsen van de definitieve prothese trad er nog een significante verbetering op in het comfort van de patiënt. (44) Bovenstaande studies zijn case control studies die de subjectieve mening van patiënten beschrijven die allen dezelfde behandeling hebben ondergaan. In een gerandomiseerde studie van Fisher en Stenberg in 2006 (46) bleek dat patiënten met onmiddellijke belasting meer tevreden waren over de behandeling. Andere studies rapporteerden dat patiënten die pas na enkele maanden prothetisch zijn behandeld een gelijkaardig niveau van tevredenheid bereiken. (44) Het doel van deze thesis is enerzijds het nagaan van eventuele verschillen in overleving en succes tussen NanoTite en OSSEOTITE implantaten die 8

14 onmiddellijk zijn belast, en anderzijds een beschrijving geven van de opinie van de patiënten die behandeld zijn met onmiddellijk belaste implantaten. 9

15 III. Artikel A part of this chapter was submitted as: Martens F, Vandeweghe S, Browaeys H, De Bruyn H. Peri-implant outcome of immediately loaded OSSEOTITE and NanoTite implants with a fully arched implant fixed denture: a 5- year prospective case series International Journal of periodontics and restorative dentistry 10

16 Introduction Early and immediate loading in fully edentulous jaws results in outcomes similar to those for classical one- or two-stage delayed protocols. 47 Several prospective studies report survival rates ranging from 91.3 to 100% for immediate loading in the mandible. Survival rates in the maxilla range from 88.5 to 100%; poorer reported outcomes may be due to poor bone quality. 34,36,38,39 By and large, these protocol modifications have significantly reduced treatment time, improving patient satisfaction. 44 With regard to surface topography, an improved survival rate has been reported for moderately rough-surfaced implants compared with machined surfaces, especially in demanding conditions such as poor bone quality. 6,48 Furthermore, the introduction of nanotechnology to implant surfaces has enhanced the implant osteoconductivity. 42 Clinical studies, although limited in number and follow-up time, indicate that nanosurfaced implants may be more successful, especially when immediately loaded. Theoretically, the bioactive topographical feature, which enhances the initial osseointegration cascade, should enhance bone-to-implant contact and thus implant success. 43,49 Literature on patient s satisfaction with implant treatment is scarce, especially when an immediate loading protocol is performed. According to recent prospective studies, patient s comfort and esthetics improved significantly after immediate loading in comparison with the pre-operative situation. 44,45 The first aim of the current prospective study was to evaluate results for immediately loaded full-arch provisional bridges placed on dual acid-etched titanium implants with NanoTite and OSSEOTITE surfaces (BIOMET 3i). Clinical outcome in terms of 11

17 implant survival, crestal bone remodeling, and peri-implant health were assessed for up to 6 years in periodontally compromised patients. The second aim of the present study was to describe patient opinion regarding treatment outcome and assess the prosthetic quality and encountered prosthetic complications. Materials & Methods Patient selection The study population consists of 33 patients consecutively treated with immediately loaded implants to rehabilitate the maxilla and/or mandible. Patients with a history of radiation therapy, use of medication for cancer prevention, or irregular compliance with dental care or maintenance were excluded, but smokers were included. All patients were classified as periodontally compromised based on tooth loss at a young age and/or ongoing periodontal disease in remaining teeth. All patients were enrolled in a periodontal treatment protocol prior to implant surgery, including nonsurgical or surgical periodontal infection control, with selective extractions of hopeless teeth at least 2 months prior to implant placement. Oral hygiene instructions were given at each visit. Surgical planning was based on clinical and radiographic inspection, which included panoramic radiograms and/or threedimensional radiographic evaluation using CT or cone-beam CT. Included patients had to have enough bone to insert at least 4 implants with a minimal diameter of 4mm and minimal length of 10mm. All implants placed were BIOMET 3i implants with an OSSEOTITE or NanoTite surface. In some patients OSSEOTITE and NanoTite implants were placed alternately to allow comparison of both surfaces within the same patient. 12

18 Figure 1: Flow chart of the study design. Of 33 patients, 8 patients received 33 implants in the mandible, 25 patients received 130 implants in the maxilla. After a mean follow- up 57 months, 104 NanoTite implants and 31 OSSEOTITE implants were available for statistical analysis. Treatment Protocol and follow-up Implants were placed by 2 experienced surgeons (HDB, HB) after crestal incisions were made and full-thickness flaps were raised. The drilling protocol was adapted to the bone quality in order to enhance initial implant stability. All implants were placed subcrestally or crestally, taking into consideration the biologic width in relation to the 13

19 soft-tissue thickness. Impressions and bite registrations were taken in conjunction with the implant placement, in accordance with a previously described treatment protocol. 50,51 All implants were loaded by a trained prosthodontist (SVDW) with a unit screw-retained metal-reinforced acrylic provisional bridge manufactured by the dental technician within 72 hours after surgery. Minor occlusal adjustments were made to achieve spreading of the occlusal load and establish bilaterally protected articulation with group function. Patients were enrolled in a recall program after implant placement to ensure a good oral hygiene and to control the loading of the provisional implant fixed complete denture (IFCD). Digital periapical radiographs were taken after implant insertion (baseline) and during 2 research follow-up visits in order to visualize the crestal marginal bone-to-implant contact. These were analyzed by the same clinician (FM). Twenty randomly selected radiographs were measured twice by two clinicians to analyze intra- and interexaminer reliability. Plaque and bleeding on probing were evaluated at four places around each implant, using the Mombelli index (table 1). 52 The presence of plaque was tested by running the side of the probe around the implant surface at the peri-implant sulcus. Bleeding was evaluated by gently sliding a periodontal probe through the sulcus. A mean pocket depth was calculated per implant. The definitive IFCD was evaluated after on average 26 and 57 months by the same clinician (FM). The guidelines for the assessment of clinical quality and professional performance (Californian Dental Association 1977) were adapted and used to evaluate design, fit, occlusion/articulation and esthetics (table 2)

20 Table 1: Plaque & Bleeding assessment according to Mombelli

21 Rating Perfect Overall Comment R is of satisfactory quality and expected to protect the implant and peri- implant tissues and facial height. Natural appearance with tissues. Design Fit Occlusion/articula tion Axially loaded implants; Contour of R is in teeth, allowing uncompromised phonetics and good oral hygiene measures. Implant- abutment and abutment- crown harmony without gap or overhang. Central occlusion and disclusion of the crown in connection is smooth. Esthetics No mismatch in colour/shade/ translucency between R and adjacent teeth. Perfect lip filling. Acceptable R is of acceptable quality but exhibits some features that deviate from the ideal. Slightly over contoured or under contoured R with no negative interference with phonetics, loading or oral hygiene measures. Abutment- crown connection has a clinically insignificant retention or overhang. Absence of occlusal contact resulting from antagonistic situation and disclusion during lateral articulation or protrusion. Clinically insignificant mismatch in colors/shade/ translucency. Discoloration of acrylic teeth. Lip fill and facial height in harmony. To be corrected for prevention R is not of an acceptable quality and future damage of the implants and/or prosthesis and/or peri- implant tissues is likely to occur. R is bulky and is interfering with phonetics and/or loading and/or oral hygiene measures. Partial misfit between abutment- prosthesis and/or gap between abutment and implant. Premature contacts during occlusion/articulation/ protrusion which can be adjusted by the dentist without having to remove the R. Esthetically disturbing mismatch in color/shade/ translucency with adjacent teeth. Heavy discoloration and/or damage of teeth. Inharmonious lip fill and/or facial height. Redo R is harmful to implants and/or peri- implant tissues and failures/complicati ons are likely to occur. Not correctable R with marginal under contouring or over- contouring damaging the peri- implant tissues or bone. Complete misfit between abutment prosthesis and/or abutment implant. R lacks occlusion or the occlusion/articulation cannot be adjusted without repair by the dental technician. Gross esthetic disharmony in lip fill/facial height/color/shade/ translucency. Fractured surfaces or porosities. Can Only be corrected by dental technician. Table 2: Quality evaluation rating system, adapted from the Californian Dental Association concept which was originally not intended for fixed implant- retained prosthesis. 53 R = Restoration 16

22 Questionnaire Study Patient's opinion was assessed at each visit using 2 questionnaires: The OHIP-14 questionnaire and visual analogue scale (VAS) questions. The clinicians that were involved in surgery or prosthetic treatment were not present when the patient was filling in the questionnaires. The OHIP-14 questionnaire is based on 14 questions divided into seven different domains. Questions are displayed in table 3. 54,55 Two questions per domain reflect respectively on: functional limitation, physical disability, physical pain, psychological disability, psychological discomfort, social disability and handicap. The questions are answered on a Likert-like scale from 0 to 4. Zero was defined as the maximal positive result indicative of total absence of problems; 4 correspond to maximal negative answer or always a problem. A general OHIP-14 score for each patient was calculated as the sum of all the questions in this questionnaire (14) divided by 14. With the VAS questions, patients marked their opinion on a 100 mm scale between 0 (maximal disagreeing or minimal experienced) and 100 (maximal agreement or maximal experienced). The patient-centered outcomes of the questionnaires were related to overall comfort, eating comfort, speaking comfort and esthetics. These specific factors provide an insight into the opinion of the patient with implantsupported restorations. The answers are displayed in table 4 and divided in 5 categories. 1 was defined as the maximal negative answer; 5 correspond to maximal positive result. A general satisfaction score for each patient was calculated as the sum of all the questions in this questionnaire (8) divided by 8. At all postoperative time points, patients were also asked whether they would repeat the treatment if necessary or whether they would recommend it to other people. In addition, 17

23 questions were asked about the ease of oral hygiene measures with the temporary and final restorations. 56 Table 3: OHIP- 14 questionnaire 54,55 Table 4: VAS- score questions 56 18

24 Statistical Analysis Pairwise analysis of crestal bone changes and clinical parameters was performed with the Wilcoxon Signed Ranks test. Correlations between clinical and radiographic measurements were calculated using the Spearman s Rank correlation coefficient. The intra- and interexaminer reproducibly of the radiographic analysis was calculated by means of the Spearman s correlation coefficient and Wilcoxon Signed Rank tests. All tests were performed using SPSS (version 19.0; SPSS, Chicago, IL, USA) and were evaluated on a 0.05 significance level. For patient s opinion and prosthetic evaluation, descriptive statistics were used. Results Implant survival In total, 33 patients (16 females and 17 males) receiving 163 implants were evaluated. The mean age was 66 years (range 39-89; SD 12.8). Twenty-five patients received 130 implants in the maxilla, and 8 received 33 implants in the mandible. One patient received implants in both the jaws (Table 5 and Figure 2). All implants were long (10 to 15mm), and were 4 mm in diameter. Only one implant was 3.25mm wide; 5 were 5mm. During provisionalization, 6 implants were lost in 4 patients, bringing the one-year survival to 157 of 163 (96.3%). At the first investigation interval of 26 months (range 7-48; SD 13.6), no further failures had occurred, although 2 patients with 8 implants were lost from recall. At the second research examination, after a mean follow-up of 57 months (range 34-77, SD 12.4), one patient had lost 3 implants, and 2 patients with a total of 11 implants were lost from follow-up. Hence a total of 9 implants out of 163 had failed (5.5%). The drop-out is 4/33 patients (12%), of which 3 were unaccounted for and 1 died. All failures occurred in the maxilla, 19

25 bringing the failure rate there there to 6.9%. In the mandible, implant survival was 100%. Figure 2: Locations of 163 implants in 33 patients, according to tooth position. The left histogram represents the mandible, the right histogram the maxilla. Table 5 : Implant Length in relation to jaw position Peri-implant bone and health After a mean follow-up of 57 months (range 34-77; SD 12.4), mean total crestal bone loss calculated from the day of surgery was 1.6mm (n=135; SD 0.77; range ) and 1.40 (range ; SD 0.46) with the implant and the patient as the statistical unit, respectively. There was no statistically significant difference (p=0.23) in the mean bone loss after 26 months (1.5mm; SD 0.69; range 0-3.2). Mean crestal bone 20

26 loss for the OSSEOTITE implants was 1.7mm (n=31; SD 0.80; range ) and for the NanoTite implants it was 1.5mm (n=104; SD 0.76; range ). Multivariate analysis was performed, and this difference was not statistically significant (p>0.05). In the maxilla, the mean crestal bone loss was 1.5mm; in the mandible 1.6mm. This difference was not significant (p=0.708). There was no significant difference (p=0.59) in bone loss between implants placed in bone of poor quality (1.5mm) and those placed in bone of good quality (1.4mm). The bone loss around 22 OSSEOTITE (1.56mm) and NanoTite (1.40mm) implants was pairwise compared with 11 patients who had both implants in equal number, and the difference was not statistically significant (p=0.68) The Spearman s correlation coefficient for bone-level assessment showed a high intra-examiner reliability, with a score of 0.87 (p<0.001). The differences in the mean bone level did not exceed 0.3mm (corresponding to half a thread), and the Wilcoxon Signed Rank test could not detect a significant difference (p=0.214). The mean overall and interproximal probing depth was 3.4mm (SD 0.70; range ) and 3.6mm (range ; SD 0.76), respectively. Only 4.6% of the implants had a mean interproximal probing depth of more than 5mm (Table 6). Excessive bleeding was present around 5 implants, with spontaneous bleeding evident around 2 (Table 1). There was no correlation between interproximal probing pocket depth and marginal bone level (p=0.63), according to the Spearman s correlation test. The relation between radiographic bone loss and probing pocket depth is shown in Table 3. In total 95.4% of the implants had a mean interproximal probing depth 5mm, and 79.9% had mean marginal bone loss up to the second thread. Deeper (>5mm) as 21

27 well as shallower (<4mm) pockets were present in all bone-loss groups, suggestive of the low correlation coefficient between these parameters. Despite this stable bone condition, bleeding was present around 80% of the implants, as indicated in Table 1. Figure 3: Cumulative percentage of implants and their corresponding bone loss as measured during the average 26- and 57- month examinations. As indicated on the figure, 50% of the study population had bone loss of less then 1.53mm after a mean follow- up of 57 months. 22

28 Figure 4: Boxplot of the crestal bone loss (mm) at the 2 different recall intervals. There was no statistically significant difference between bone loss after 26 and 57 months of follow- up (p=0.23). Red arrows indicate the median. 23

29 Figure 5: Boxplot of the crestal bone loss (mm) with 2 different implant topographies. There was no statistically significant difference in bone loss between implants with a NanoTite or OSSEOTITE topography (p=0.68). 24

30 Table 6: Cross table of individual implants presented according to the marginal bone loss and the mean interproximal pocket probing depths. Implants indicated in green represent a low disease risk. Implants indicated in orange (19.3%) are the ones that can be considered at risk for disease and should be monitored more closely. Implants indicated in red, 1.5% of the total group, showed bone loss past the third thread at the 57- month interval. These may be at risk for peri- implantitis. Due to probing difficulties or some unreadable radiographs, not all pockets could be related to a corresponding bone loss value. In total 129 implants were evaluated. Questionnaires In total, 29 patients filled out the questionnaires at the 56 months interval. The answers to the OHIP-14 questionnaire and VAS questions are displayed in table 7 and 4, respectively. Mean overall OHIP-14 score was There was no difference between the different domains. According to the VAS questions, the patients rated the esthetics of their prosthesis perfect in 62% of the cases. Mean overall score on 25

31 the VAS questions was 7.7/ bridges were evaluated by a dentist at the 56 months interval. Results are displayed in table 8. The dentist rated the prosthesis perfect in 38% for design, 62% for fit, 52% for occlusion/articulation and 38% for esthetics. The overall score was perfect in 34% of the patients. There was a significant discrepancy in quality assessment on esthetics and overall score between clinician and patient (P<0,005 - Wilcoxon signed-rank test). Table 7: Result of the OHIP- 14 questionnaire 26

32 Table 8: Results from the Californian Dental Index 27

33 28

34 Figure 6: Case presentation of an immediate loading treatment in the maxilla. Patient is a 42- year- old male. A and B: Pre- operative clinical photographs show extensive tooth loss and caries C: The surgical guide made by the dental technician shows the tooth positions and contains space for bite- registration material. It can be positioned in exact occlusion. On the palatal side, enough resin has been removed to allow drilling. There is sufficient palatal support to keep the guide in place during surgery and bite registration. The resin teeth are incorporated in the provisional prosthesis after surgery. D: Clinical image of the healing abutments immediately after impression making. The mucoperiosteal flap was sutured around the impression copings in order to avoid having impression material in contact with the alveolar bone. E: Impression analogs are connected to the impression coping by the surgeon and sent to the lab to create a working model. F. Bite registration was performed with the guide plate. G and H: Frontal and occlusal view of the provisional bridge made by the dental technician, placed within 72 hours after surgery. Occlusion and articulation were controlled to allow a correct occlusal spread. H and I: Peri- apical radiographs 6 months after placement of the provisional construction. Fit of the provisional bridge is good and initial bone remodeling has taken place. Figure 7. Apical radiographs at 6 months (a), 2 years (b), and 5 years(c) after immediate loading. The porcelain- fused- to- metal bridge is supported by 6 implants. Red arrows indicate the bone level. 29

35 Discussion The aim of the present prospective study was to evaluate survival, crestal bone level changes, and peri-implant health of NanoTite and OSSEOTITE dental implants used for complete rehabilitation of the maxilla and/or mandible using an immediate loading protocol. Immediate loading is supported by numerous reports with satisfactory outcomes 34,50,51,57 and the present study shows a high clinical cumulative survival rate of 94.4% after an average of 5 years. Implant survival was 100% in the mandible, in line with other published prospective clinical studies. 32,39 Cumulative survival in the maxilla was 93.7% after 57 months. This outcome is consistent with recent literature. 58 It should be noted that included patients had a history of periodontal disease and tooth loss at young age, and such a history has been associated with a threefold higher implant failure rate. 59,60 Other studies have reported comparable survival rates of immediately loaded maxillary BIOMET 3i implants. 22,23 Immediately loaded dual-acid-etched BIOMET 3i implants placed in 26 patients (8-10 implants per case) experienced no failures after months of follow-up. 32 The lower number of implants per patient in the present study (4-6 implants) may have resulted in a more unevenly distributed occlusal load and higher micro-motion on each individual implant, another potential contributing factor to increased failure risk. Clinical studies of less than 5 implants per jaw have been clearly associated with higher failure rates as compared to clinical studies with 5-8 implants per jaw. 58 In the present study, the bone volume in 11 non-smoking patients only allowed for placement of 4 implants per jaw. Four out of 44 implants (9.1%) failed in this group, including 3 after more than 2 years of loading. Five out of 74 implants (6.7%) failed in patients who received 6 implants per jaw. This clinical 30

36 difference points to the importance of sufficient occlusal load spreading especially in immediately loaded maxillary restorations. The surface roughness of BIOMET 3i implants has a roughness (Sa value 0.5µm) that has been shown to be relatively smooth compared to that of competing implants. 61 This may be helpful in maintaining peri-implant health especially in periodontally involved patients. Use of this surface up to the abutment level has been demonstrated not to increase the risk of peri-implantitis. 62 The present study confirms this; crestal bone levels did not change after the initial biologic width and remodeling was established. No changes in peri-implant health were observed between the first (average 26-month) and second (average 57-month) research follow-up visits. Although some studies have proven that nanotechnology improves osteoconductivity, this advantage only counts during initial bone healing in compromised cases. Hence, the lack of a difference in crestal bone loss between full OSSEOTITE or full NanoTite surfaced implants seems logical and agrees with earlier studies. 24,60 Bone loss of less than 1.5mm during the first year after loading and 0.2mm annually thereafter has been defined as criteria for implant success. 63 In the present study, this would allow for a total crestal bone loss of mm, as the range for followup was months. Observed crestal bone loss was below these threshold values for 75% of the evaluated implants. This bone loss was based on baseline measurements recorded on the day of surgery. However, recent clinical studies have revealed that initial bone remodeling takes from 3 to 6 months after single-stage implant placement. Hence, a waiting period between abutment placement and loading, as is often the case in delayed loading studies, excludes a large portion of 31

37 the total crestal bone loss. A comparison of immediate loading with early/immediate loading is therefore scientifically biased. 64,65 A few studies have reported bone loss of mm with BIOMET 3i implants, 22-24,66 less than the 1.6 mm found in the present study. An explanation may be found in the limited follow-up time of some of those studies. No correlation was found between probing depth and bone loss, pointing to the low predictive value of probing to detect ongoing disease. A total of 48.9% and 81.4% of the implants showed bone loss not exceeding the first or second implant thread, respectively (Table 6). Only 19% of the implants had bone loss of more than 2.1mm. When bone loss of more than 2.1mm and pocket depths of more than 5mm are considered together (the diagnostic criteria for peri-implantitis), only 1.5% of the study implants fall into this category. The present study makes it clear that concerns about high peri-implantitis prevalences are unfounded. This confirms other reports and it clearly indicates that a combination of bone loss and probing depth must be considered. 67 Use of the NanoTite or OSSEOTITE surface, rough to the top, does not appear to be prone to peri-implant disease According to the OHIP-14 questionnaire, overall comfort was very high. This in accordance with other recent prospective studies. 44,45 Although patient s subjective parameters are only recorded at the 56-month time interval, it clearly indicates that the patient satisfaction with immediate loading is very high. The idea of patient satisfaction should probably not been overestimated because other studies have revealed that delayed loaded patients regain the same level of satisfaction once their prosthesis is in place

38 According to the VAS questions, 90% of the patients would undergo the same treatment again and almost 97% would recommend the treatment to others. Most patients rated the achieved esthetics of their prosthesis made by the referring dentist very positively and they were also pleased with the phonetics. The mean VAS scores for the ease of oral hygiene in our study was 64/100 (SD = 13.2; range 0-100) at the 56 month interval. This is lower when comparing to other studies (score ) 6 and may be due to the fact that the follow-up in those studies were only 1 year. This is a clear indication for the need to follow-up the patients using a strict maintenance protocol, in order to reinforce oral hygiene whenever required on an individual basis. 62% of the patients rated their prosthesis esthetically very good. This is in contrast with the opinion of the dentist, were only 31% of the prosthesis were rated perfect for esthetics. This difference was statistically significant and in accordance with previous studies, which evaluated implant supported single crowns. This points out that most patients are less critical than the dentist regarding esthetics of the implant fixed complete denture

39 IV.samenvatting 34

40 Het doel van deze thesis was om immediate belasting van dentale implantaten evalueren bij patiënten die een verleden hebben van parodontitis. Aan de hand van een onderzoek werden zowel objectieve als subjectieve parameters geregistreerd. De patiënten werden onderworpen aan een klinisch en radiografisch onderzoek om de objectieve parameters vast te leggen, en vervolgens werden er enkele vragenlijsten ingevuld door tandarts en patiënten om de subjectieve parameters te registreren. De implantaten die in de studie werden onderzocht waren BIOMET 3i implantaten met 2 verschillende oppervlaktetopografieën; een tweemaal geëtst titanium oppervlak (OSSEOTITE ) en met additionele CalciumPhosphaat coating (NanoTite ). De studie liet toe om implantaatoverleving en crestaal botverlies (parameter voor succes) van beide oppervlakken te vergelijken. Na een gemiddelde opvolgingstijd van 5 jaar is er geen verschil in overleving of succes tussen beide oppervlakken waar te nemen, ongeacht of deze geplaatst werden in bot van goede of slechte kwaliteit. Er was met andere woorden geen verschil in crestaal botverlies en faling tussen beide implantaattypes. De overlevingswaarde van 94% na 5 jaar is iets lager dan andere prospectieve studies met hetzelfde implantaatsysteem. Dit is te wijten aan de kortere opvolgingsduur van de meeste studies en het gegeven dat de patiënten in onze studie een duidelijk verleden hadden van parodontitis. Rondom elk implantaat werden pockets gemeten en deze werden gelinkt aan het crestale botniveau. Op deze manier kon er gekeken worden of implantaten met diepe pockets eveneens hoge botverlieswaarden hadden. Slechts in 1.5% van alle implantaten kon een pocketdiepte van 5mm gelinkt worden aan botverlies tot voorbij 35

41 de tweede winding van het implantaat. Dat wil zeggen dat diepe pockets rondom een implantaat niet altijd gepaard gaan met progressief botverlies of het voorkomen van peri-implantitis en visa versa. Patiëntentevredenheid werd aan de hand van vragenlijsten nagegaan. Bij het begin van de behandeling werden deze vragenlijsten echter niet afgenomen waardoor een vergelijking met de pre-operatieve situatie onmogelijk was. Desondanks kan er worden vastgesteld dat de grote meerderheid van de patiënten een hoge tevredenheid heeft met de huidige gebitssituatie. Als laatste werd de suprastructuur op de implantaten beoordeeld door een tandarts. Dit is echter een subjectieve beoordeling en deze kan tussen variëren tussen verschillende clinici. Er kon worden vastgesteld dat de brugstructuur in >95% van de casussen een acceptabele of perfecte kwaliteit had. De beoordeling van de tandarts over de esthetiek verschilt van deze van de patiënt. De tandarts is kritischer over het prothetische werk dan de patiënt. 36

42 V.Referentielijst 37

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