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RANDOMISED CONTROLLED CLINICAL TRIAL Marco Esposito, Carlo Barausse, Roberto Pistilli, Vittorio Checchi, Michele Diazzi, Maria Rosaria Gatto, Pietro Felice Posterior jaws rehabilitated with partial prostheses
supported by 4.0 x 4.0 mm or by longer implants:
Four-month post-loading data from a randomised
Marco Esposito, DDS,
PhD
Freelance researcher and
Associated Professor,
Department of Biomaterials,
Key words
posterior jaws, short dental implants The Sahlgrenska Academy at Göteborg University, Göteborg, Sweden Purpose: To evaluate whether 4.0 x 4.0 mm dental implants could be an alternative to implants at
least 8.5 mm long, which were placed in posterior jaws in the presence of adequate bone volumes.
Carlo Barausse, DDS
Resident, Department of
Materials and methods: One hundred and fifty patients with posterior (premolar and molar areas)
Biomedical and Neuromotor mandibles having at least 12.5 mm bone height above the mandibular canal or 11.5 mm bone height Sciences, Unit of Peri-odontology and Implantol- below the maxillary sinus, were randomised according to a parallel group design, in order to receive ogy, University of Bologna, Bologna, Italy one to three 4.0 mm-long implants or one to three implants which were at least 8.5 mm long, at three centres. All implants had a diameter of 4.0 mm. Implants were loaded after 4 months with de- Roberto Pistilli, MD
Resident, Oral and Maxillo-
finitive screw-retained prostheses. Patients were followed up to 4-month post-loading and outcome facial Unit, San Filippo Neri measures were prosthesis and implant failures, any complications and peri-implant marginal bone Hospital, Rome, Italy Vittorio Checchi,
Results: No patients dropped-out before the 4-month evaluation. Three patients experienced the
DDS, PhD
Researcher, Department of
early failures of one 4.0 mm-long implant each, in comparison to two patients who lost one long Medical Sciences, University implant each (difference in proportion = 0.01; 95% CI -0.06 to 0.09; P = 0.50). Consequently, two of Trieste, Trieste, Italy prostheses in each group could not be delivered as planned (difference in proportion = 0; 95% CI Michele Diazzi, DDS
Private practice in Bologna,
-0.07 to 0.07; P = 0.69), and one patient from each group is still waiting to have their prostheses delivered. Three short implant patients experienced three complications versus two long implant Maria Rosaria Gatto,
patients (difference in proportion = 0.01; 95% CI -0.06 to 0.09; P = 0.50). There were no statistically significant differences in prosthesis failures, implant failures and complications. Patients with short Researcher, Department of Biomedical and Neuromotor implants lost on average 0.38 mm of peri-implant bone at 4 months and patients with long man- Sciences, Unit of Peri- dibular implants lost 0.42 mm. There were no statistically significant differences in bone level changes odontology and Implantol-ogy, University of Bologna, up to 4 months between short and long implants (mean difference = 0.04 mm; 95% CI: -0.041 to 0.117; P = 0.274).
Pietro Felice, MD,
Conclusions: Four months after loading, 4.0 x 4.0 mm implants achieved similar results as
DDS, PhD
Researcher, Department of
8.5 x 4.0 mm-long or longer implants in posterior jaws, however 5 to 10 years post-loading data are Biomedical and Neuromotor necessary before reliable recommendations can be made. Sciences, Unit of Peri-odontology and Implantol-ogy, University of Bologna, Conflict-of-interest statement: Global D (Lyon, France) donated implants and prosthetic components
and Tecnoss (Coazze, Italy) donated the biomaterials used in this study. Data property belonged to the Correspondance to:
authors and by no means did the manufacturers interfere with the conduct of the trial or the publica- Dr Marco Esposito, Casella Postale 34, tion of its results. 20862 Arcore (MB), Italy Email: [email protected] Eur J Oral Implantol 2015;8(3):221–230 Esposito et al 4.0 x 4.0 mm versus longer implants in posterior jaws
ing the quality of reports of parallel group randomised Short dental implants are used as an alternative to long implants in intentionally augmented bone, in order to support fixed prostheses in the rehabili- „ Materials and methods
tation of patients with atrophic jaws. There are a few randomised controlled trials (RCTs) comparing This study was designed according to a randomised the effectiveness of dental prostheses supported controlled multicenter trial of parallel group design by short implants with those supported by long with two arms, using, whenever possible, a blinded implants placed in augmented bone1-12. The results outcome assessor.
of these ongoing trials having follow-ups of up to Any partially edentulous patient missing teeth 5-years post-loading, suggest that 5.0 to 8.0 mm- in the premolar and molar area requiring one to long implants can be a viable, if not a better, alterna- three dental implants, being 18 years or older, and tive to augmentation procedures, especially in pos- able to sign an informed consent form was eligible terior mandibles.
for inclusion in this trial. Vertical bone heights at More recent clinical questions include whether implant sites had to be at least 12.5 mm above the to use short implants also in those situations were mandibular canals and 11.5 mm below the maxillary long implants could have been used and how short sinuses. Bone thickness had to be at least 6.0 mm could an implant be in order to be able to provide as measured on cone beam computer tomography a good long-term outcome. There are at least two (CT) scans. Each patient was treated at only one manufacturers (Straumann and Global D) market- side of the jaw and received one prosthesis only, ing transmucosal 4.0 mm-long implants, and one according to a parallel group design. Exclusion cri-of these implant types was evaluated in a multicen- tre non-controlled single-cohort prospective 2-year • general contraindications to implant surgery;post-loading study13. In this study 100 4.0 mm-long • subjected to irradiation in the head and neck area;implants were placed in the posterior region of 32 • immunosuppressed or immunocompromised;partially edentulous patients (three or four implants • treated or under treatment with intravenous in each patient). Seven implants failed before loading in 4 patients and 2 additional patients were excluded • untreated periodontitis;for unclear reasons (most likely because of implant • poor oral hygiene and motivation;failures) so that only 26 patients received their pros- • uncontrolled diabetes; theses. Two years after loading one patient died and • pregnant or nursing;one requested to have all his implants removed13. • substance abusers;This means that the treatment with short implants • psychiatric problems or unrealistic expectations;failed in 23% (seven out of 31) of the treated patients • lack of opposite occluding dentition to the area 2 years after loading, and these initial figures are not intended for implant placement; very promising.
• acute or chronic infection/inflammation in the The aim of this RCT was to compare the outcome area intended for implant placement; of partial fixed prostheses supported by 4.0 x 4.0 mm • participation in other trials, if the present protocol implants with prostheses supported by implants at could not be properly followed; least 8.5 x 4.0 mm long placed in posterior jaws, • referred only for implant placement and not hav-which have adequate bone volumes to be treated ing the prosthesis or maintenance procedures with medium to long implants. This report presents performed at the treatment centres; the preliminary clinical outcome up to 4-month post- • unable to attend follow-up visits for 3 years after loading. The aim was to follow-up these patients to the third year of function. The present article is • post-extractive sockets if the upper portion of reported according to the CONSORT (Consolidated the buccal wall was lower than 4 mm when com- Standards of Reporting Trials) statement for improv- pared to the palatal wall. Eur J Oral Implantol 2015;8(3):221–230

Esposito et al 4.0 x 4.0 mm versus longer implants in posterior jaws
reference point for x-ray measurement Fig 1 Illustration of 4.0 mm (a) and 13.0 mm (b) conical
Fig 2 Sequence of drills used to prepare the implant sites
transmucosal Global D TwinKon® Universal SA2 implants for shorter implants. Please notice the presence of stops used in this study. Implants are made of Ti4V6Al alloy, have with the drills.
a sand-blasted acid-etched surface and a peculiar external connection.
Patients were categorised into three groups for 1 min with 0.2% chlorhexidine. The area was according to what they declared: non-smoker, mod- locally anaesthetised with infiltration of articain with erate smoker (up to 10 cigarettes per day) and heavy adrenaline 1:100.000. After crestal incision and flap smoker (more than 10 cigarettes per day). Patients elevation, or in the case of post-extractive implants were to be recruited and treated in three different after curettage of the socket, patients were randomly centres (50 patients per centre) by three different allocated, by opening the sequentially numbered operators, however one operator recruited and envelope corresponding to the patient recruitment treated only four patients, so his remaining quota number, where either they received one to three of patients were taken by one of the two remaining 4.0 x 4.0 mm long implants (Fig 1a) or one to three operators (Dr Pietro Felice), who treated patients in implants which were at least 8.5 mm long (8.5, 10.0, two Italian private practices and one university hos- 11.5 and 13.0 mm-long; Fig 1b) and 4.0 mm in diam- pital, whereas the other operator (Dr Roberto Pis- eter, according to the standard procedures as recom- tilli) treated patients both in a hospital and a private mended by the manufacturer (TwinKon® Universal practice. All operators followed similar standardised SA2, Global D, Lyon, France). Surgical stents were procedures. used to optimise implant positioning after flap eleva- The principles outlined in the Declaration of tion. Drills with stops and increasing diameters were Helsinki on clinical research involving human sub- used to prepare the implant sites, which were slightly jects were adhered to. The study was approved by underprepared (Fig 2). At implant insertion, the sur-the ethical committee of the Ospedale Maggiore in gical motor unit was set at a torque of 25 Ncm and Bologna, Italy on 14 June 2013 (Prot.N.554/CE). All resistance at implant insertion was recorded as < 25 patients received thorough explanations and signed Ncm or > 25 Ncm. The transition portion from the a written informed consent form prior to being machined to the roughened surface of the implant enrolled in the trial. Approximately 10 days before neck (Fig 1) was placed about 2 mm subcrestally. In the implant placement patients received at least one ses- case of post-extractive implants, teeth were extracted sion of professional oral hygiene.
using the flapless approach, in order to try to minimise the surgical trauma as much as possible and to spare the buccal wall of the socket. Sockets were carefully „ Implant placement procedures
debrided from any remnants of granulation tissue. Two grams of amoxicillin (or 100 mg minocycline In the presence of a horizontal buccal bone to im-for patients allergic to penicillin) were administered plant gap of 2 mm or more, gaps were filled with 600 1 h prior to implant placement and patients rinsed to 1000 microns diameter granules of pre-hydrated Eur J Oral Implantol 2015;8(3):221–230 Esposito et al 4.0 x 4.0 mm versus longer implants in posterior jaws
cortico-cancellous porcine bone mixed with approxi- Patients were enrolled in an oral hygiene pro- mately 10% collagen gel (MP3, OsteoBiol, Tecnoss, gram with recall visits every 6 months for the entire Coazze, Italy) covered with a haemostatic resorbable duration of the study. Follow-ups were conducted by collagen sponge (Spongostan, 1 x 1 x 1 cm, Ethicon, independent outcome assessors (Dr Vittorio Checchi Johnson & Johnson, New Jersey, USA) of porcine ori- at Dr Pietro Felice's and Luigi Checchi's centres and gin, blocked with a cross-suture.
Dr Roberto Cassoni at Dr Roberto Pistilli's centre).
Healing abutments were placed on implants not to be submerged, and healing screws on implants to „ Outcome measures
be submerged and flaps were closed around non-submerged implants or over submerged implants with This study tested the null hypothesis that there were vicryl 4/0 sutures (Ethicon). The decision on whether no differences in the clinical outcomes between the to submerge the implant or not was based on the two procedures against the alternative hypothesis of thickness of the mucosa. Ideally all implants were to be a difference. Outcome measures were:submerged, however since these implants had a trans- • Prosthesis failure: planned prosthesis which could mucosal design, they could only be submerged when not be placed due to implant failure(s), loss of the soft tissues were sufficiently thick. Periapical radio- the prosthesis secondary to implant failure(s) and graphs (baseline) were made with the paralleling tech- replacement of the prosthesis for any reasons.
nique. If bone levels around the study implants were • Implant failure: implant mobility, removal of sta-hidden or difficult to estimate, a second radiograph ble implants dictated by progressive marginal was made. Ibuprofen 400 mg was prescribed to be bone loss or infection, and any mechanical com- taken 2 to 4 times a day during meals, in the presence plications rendering the implant unusable (e.g. of pain, as long as required. Patients were instructed implant facture). Stability of each individual im- to place 1% chlorhexidine gel on the wounds twice a plant was measured at delivery of definitive pros- day for 2 weeks, to avoid brushing and trauma on the theses (4 months after implant placement) and surgical sites, and were advised to have a soft diet for 4 months after initial loading by tightening the 1 week. No removable prostheses were allowed on abutment screws using a manual wrench with a treated areas. Sutures were removed after 10 days, 25 Ncm force with the removed prostheses.
and patients were controlled at 20 days, one and two • Any biological or prosthetic complications. months after placement of dental implants.
• Peri-implant marginal bone levels changes eval- uated on intraoral radiographs taken with the paralleling technique at implant placement, at „ Prosthetic procedures
delivery of definitive prostheses and 4 months After 3 months of unloaded healing, when necessary, after loading. Radiographs were scanned in TIFF implants were exposed, manually tested for stability, format with a 600 dpi resolution, and stored in a and impressions with the pick-up impression copings personal computer. Peri-implant marginal bone were taken using a polyether material (Impregum levels were measured using the OsiriX (Pixmeo 3M/ESPE, Neuss, Germany) and customised resin Sarl, Bernex, Switzerland) software. The soft- impression trays. Impressions of submerged implants ware was calibrated for every single image using were taken after 2 weeks of soft tissue healing. Four the known implant diameter. Measurements of months after placement, implants were manually the mesial and distal bone crest level adjacent to tested for stability and definitive metal-composite or each implant were made to the nearest 0.01 mm metal-resin screw-retained restorations, rigidly join- and averaged at implant level, then at patient ing the implants, were connected directly on the level and finally at group level. The measure- implants, in light occlusion with the antagonistic ments were taken parallel to the implant axis. dentition, and oral hygiene instructions were deliv- Reference points for the linear measurements ered. Periapical radiographs of the study implants were the most coronal margin of the implant were taken, and in the case of unreadable radio- collar and the most coronal point of bone-to- graphs, new radiographs were taken.
implant contact. Eur J Oral Implantol 2015;8(3):221–230 Esposito et al 4.0 x 4.0 mm versus longer implants in posterior jaws
„ Methodological aspects
lysed the data. The patient was the statistical unit of the analyses. Differences in the proportion of Two clinicians (Dr Vittorio Checchi at Dr Pietro patients with prosthesis failures, implant failures and Felice's and Luigi Checchi's centres, and Dr Roberto complications (dichotomous outcomes) between the Cassoni at Dr Roberto Pistilli's centre) not involved two groups were compared using the Fisher's exact in patient treatment performed all clinical measure- test and binomial 95% confidence intervals were ments without knowing group allocation. One den- computed. The non-Gaussian distribution of radio- tist (Carlo Barausse) not involved in the treatment of graphic bone levels suggested the use of non- para-the patients performed all the radiographic assess- metric tests. Difference of means for radiographic ments and therefore the different implant lengths bone levels between the groups were compared could be easily identified on the periapical radio- by Mann-Whitney U test and bias was corrected and accelerated 95% confidence intervals were A sample size calculation was performed using computed (IBM-SPSS Statistics Release 21). Com- patients whom experienced at least one implant fail- parisons between each time points and the baseline ure as a primary outcome measure with 80% power measurements were made by the Wilcoxon test for ( = 0.2) and one-sided _ = 0.05. No previous study paired data, to detect any changes in marginal peri-on the same topic was carried out at the time of implant bone levels. A chi-square test was used to the research protocol. Consequently the sample size compare the number of prosthesis failures, implant was computed on the basis of a similar study7 that failures and complications and the Kruskal–Wallis reported that 3 years after loading, 7% of patients one-way analysis of variance was used to assess the lost short implants and 10% long implants. A failure marginal bone levels amongst the centres. All statis-rate of 0.07 in the control group was estimated. The tical comparisons were conducted at the 0.05 level minimal difference which was considered clinically of significance. relevant was set at 0.08, in agreement also with the clinicians' opinion. Based on this consideration, 160 patients were needed in total, however we only „ Results
had sufficient resources to recruit 150 patients. One hundred and fifty patients with partial edentulism or One hundred and sixty-four patients were screened to be rendered partially edentulous in the posterior for eligibility, but 14 patients were not included in jaws were included in the trial: 75 patients received the trial because they did not want to be randomised 4.0 x 4.0 mm-long implants (short implant group) and wished to have longer implants. One hundred and 75 patients received 8.5 mm-long or longer and fifty patients were considered eligible and were implants (long implant group).
consecutively enrolled in the trial, four patients at A computer generated restricted randomisation Dr Checchi's centre; 96 at Dr Felice's centre who list was created. Only one of the investigators (Dr also treated those remaining 46 patients who should Maria Rosaria Gatto), not involved in the selection have been treated by Dr Checchi's centre, and 50 and treatment of the patients, was aware of the patients at Dr Pistilli's centre. Seventy-five patients random sequence and had access to the random were treated with short implants (Figs 3a to 3g) list stored in a password protected portable com- and 75 patients with long implants (Figs 4a to 4f). puter. Information on how to treat each patient All patients were treated according to the allocated was enclosed in sequentially numbered, identical, interventions.
opaque, sealed envelopes. Envelopes were opened No patient dropped out from the study before sequentially after flap elevation; therefore, treat- the 4-month follow-up and data of all patients were ment allocation was concealed to the investigators evaluated in the statistical analyses. No substantial in charge of enrolling and treating the patients.
deviations from the protocol occurred, except that All data analysis was carried out according to a Dr Checchi treated only four patients out of the 50 pre-established analysis plan. A biostatistician with patients planned and the remaining quota of his expertise in dentistry (Dr Maria Rosaria Gatto) ana- patients were treated by Dr Felice. In addition, one Eur J Oral Implantol 2015;8(3):221–230

Esposito et al 4.0 x 4.0 mm versus longer implants in posterior jaws
Fig 3 Treatment sequence of a patient with posterior mandibular edentulism randomly allocated to 4.0 x 4.0 mm implants: a) preoperative CBCT
showing the measurements to evaluate patient eligibility; b) surgical area after flap elevation; c) 4.0 x 4.0 mm-long implants to be placed; d) baseline
periapical radiograph taken after implant placement, showing two 4.0 x 4.0 mm-long implants; e) periapical radiograph taken at delivery of definitive
prosthesis 4 months after implant placement; f) periapical radiograph taken 4 months after initial loading; g) clinical view at 4-month post-loading.
Fig 4 Treatment sequence of a patient with posterior mandibular edentulism randomly allocated to the 8.5 x 4.0 mm or longer implant group: a)
preoperative CBCT showing the measurements to evaluate patient eligibility; b) baseline periapical radiograph taken after implant placement showing a
8.5 x 4.0 mm-long implant; c) clinical view after 4 months of non-submerged healing; d) periapical radiograph taken at delivery of definitive prosthesis
4 months after implant placement; e) periapical radiograph taken 4 months after initial loading; f) clinical view at 4-month post-loading.
Eur J Oral Implantol 2015;8(3):221–230 Esposito et al 4.0 x 4.0 mm versus longer implants in posterior jaws
Table 1 Patient and intervention characteristics.
4.0 mm-long implants
8.5 mm or longer
implants (75 patients)
Mean age at recruitment (range) Smokers (smoking >10 cigarettes) No. of implants in maxillas No. of post-extractive implants No. of augmented post-extractive implants No. of implants placed with < 25 Ncm torque Mean implant length No. of patients with submerged implants No. of patients receiving 1 implant No. of patients receiving 2 implants No. of patients receiving 3 implants No. of patients rehabilitated with metal-resin prostheses Table 2 Summary of the main results expressed as number of patients who experienced at least one negative event. All
patients had only one negative event each.
Differences in 95% CI
75 patients
75 patients
Patients with failed prostheses Patients with failed implants Patients with complications patient of Dr Felice's group received a provisional P = 0.69; Table 2). Two prostheses (one from each resin prosthesis instead of the definitive one because group) were delivered with 4 months delay and two of financial problems.
patients (one from each group), at the moment of Patients were recruited and had their implant writing this article, had their replacement implants placed from September 2013 to February 2014. The healing unloaded.
follow-up of all patients was 4-month post-loading.
Five patients experienced one implant failure The main baseline patient and intervention char- each: three short and two long implants failed. acteristics are presented in Table 1. Initially, 124 The difference in proportions for implant failures implants were placed in the short group and 116 in was not statistically significant (difference in pro-the long group. There were no apparent significant portion = 0.01; 95% CI -0.06 to 0.09; P = 0.50; baseline imbalances between the two groups with Table 2). In the short implant group one implant in the exception that more 4.0 mm-long implants were position 16, inserted with a torque < 25 Ncm, was placed in mandibles. found to be mobile and painful at percussion. The The main results up to 4-month post-loading are implant was removed and immediately replaced summarised in Table 2. by an identical implant 11.5 mm-long. It was suc- Two prostheses could not be placed when cessfully loaded 4 months after. One immediate planned because of early implant failures at both post-extractive implant in position 44 and inserted groups. The difference in observed proportions for with a torque < 25 Ncm, was found to be mobile prosthesis failures was not statistically significant 4 months after insertion and immediately replaced (difference in proportion = 0; 95% CI -0.07 to 0.07; with an identical implant 10.0 mm long. The implant Eur J Oral Implantol 2015;8(3):221–230 Esposito et al 4.0 x 4.0 mm versus longer implants in posterior jaws
has not been loaded yet. Another implant, inserted implant placement and 4 months after loading (95% with a torque < 25 Ncm in position 36, was mobile CI: -0.041 to 0,117; P = 0.274) (Table 4) between and painful during impression taking and there- the two groups for peri-implant bone level changes.
fore was removed. It was not replaced since there There were no statistically significant differences were successful implants in positions 35 and 37. for failures, complications and marginal bone level Two long implants failed: one 13 mm-long implant changes at 4-month post-loading between the three in position 26 was found to be mobile and painful centres (Table 5).
at percussion after 4 months. It was removed and immediately replaced with a short but wider implant (4.7 x 6.0 mm, I-RES Shape 1, I-RES, Milan, Italy). After 4 months of submerged healing the implant was successfully loaded. Another 11.5 mm-long im- This study evaluated whether a 4.0 x 4.0 mm implant plant placed as an immediate post-extractive implant supporting a partial fixed prosthesis could be at higher in position 35 with an insertion torque < 25 Ncm was risk of failure than longer implants when placed in found to be mobile and painful 3.5 months after posterior jaws with adequate bone volumes. We were placement. The patient confessed to playing with the interested in assessing the clinical performance of very tongue on the implant. The implant was removed short implants (4.0 mm long) with a conventional and immediately replaced with an identical 10.0 x diameter of 4.0 mm in order to understand what is 4.0 mm implant inserted with a torque > 25 Ncm. the minimal amount of bone in order to be able to The implant was still unloaded at the time of writing support functionally loaded dental implants.
this manuscript Previous studies suggested that short implants Five patients experienced one complication each: can achieve clinical results which are as effective, if three complications occurred for short implants not better, than long implants placed in augmented and two for long implants. There was no statistic- bone up to 5 years after loading, however often sur- ally significant differences with regard to complica- geons use short implants with wider bodies to com- tions between the two groups (difference in pro- pensate for the lack of implant height3,5,14,15. While it portion = 0.01; 95% CI -0.06 to 0.09; P = 0.50; is still unclear whether this ‘compensation' is actually Table 2). The following complications occurred needed, preliminary results of this and many other tri-for short implants: two patients experienced some als8,11,12,15-18 in which 5.0 to 6.0 mm-long implants pain when touching the implants. Both implants with diameters of 4.0 to 5.0 mm were used suggest were mobile and were removed. Another patient that short implants with diameters of 4.0 to 5.0 mm lost the cover screw 20 days after surgery, which perform well, at least up to 5-years post-loading. was replaced without any consequences. The two When comparing the present data to those of implants belonging to the long implant group cre- previous similar RCTs16,18,19, all trials showed iden- ated pain in patients when under pressure. Both tical trends: there were similar outcomes between implants were mobile and were removed. Failures 5.0 to 6.0 mm-long implants and 10.0 mm or longer were not considered as complications, unless pain implants up to 1-year post-loading, in the presence was present, therefore, the presence of pain was of adequate bone volumes. Obviously follow-ups considered as a complication.
of at least 5-years post-loading are needed to draw Marginal bone levels are described in Table 3. more reliable conclusions. In the present trial, five Both groups gradually lost statistically significant implants were lost in total: three 4 mm-long implants marginal peri-implant bone (P = 0.001) at loading and two longer ones. All failures were detected at (0.28 mm for short implants and 0.24 mm for long abutment connection and four of the failed implants implants) and 4 months after loading (0.38 mm were replaced. No apparent sign of infection were for short implants and 0.42 mm for long implants; noted but implants were usually painful during per-Table 4). There was no statistically significant dif- cussion and mobile indicating that osseointegration ference between implant placement and loading did not take place20. Failures occurring earlier are (95% CI: -0.157 to 0.077; P = 0.324) and between easier to handle, in fact four of the mobile implants Eur J Oral Implantol 2015;8(3):221–230 Esposito et al 4.0 x 4.0 mm versus longer implants in posterior jaws
Table 3 Mean radiographic peri-implant marginal bone levels between groups and time periods.
4 months after loading
N Mean (SD)
N Mean (SD) 95% CI
N Mean (SD) 95% CI
75 0.021 (0.075) 74 0.298 (0.506) 0.205; -0.414 74 0.399 (0.264) 0.345; -0.457 73 0.255 (0.160) 0.218; -0.292 73 0.434 (0.245) 0.377; -0.497 Mann-Whitney U-test Table 4 Comparison of mean changes in peri-implant marginal bone levels at loading and 4 months after loading.
Placement – loading
Placement – 4 months after loading
N Mean (SD) 95% CI
N Mean (SD) 95% CI
74 -0.277 (0.488) -0.193; -0.388 74 -0.378 (0.248) 73 -0.237 (0.162) -0.202; -0.268 73 -0.416 (0.240) -0.157; 0.077 0.038 Mann-Whitney U-test P-value Table 5 Comparisons between the three study centres at 4 months after loading.
Dr Felice
Dr Pistilli
Dr Checchi
96 patients
50 patients
4 patients
Patients with implant failures Patients with prosthesis failures Patients with complications Mean peri-implant bone level changes in mm from implant placement to 4 months after loading were immediately replaced with other implants the The main limitation of the present trial is the short same day that they were removed, minimising patient duration of the follow-up, however longer follow-discomfort, although the delivery of the prostheses ups will be carried out. The positive aspects of this in those patients was delayed for up to 4 additional study are that all treated patients were accounted for months. In at least one case the patient declared that with no exclusions and all assessments were done by she was continuously touching the transmucosal independent assessors. The tested interventions were portion of the implant with her tongue and most of evaluated in real clinical conditions and the patient the failed implants were placed with insertion tor- inclusion criteria were rather broad. Similar results ques < 25 Ncm. It is possible that several unwanted should be obtained by other experienced operators movements disrupted the bone healing around treating patients with similar characteristics.
these implants and this could have been caused by the fibrointegration of these implants20. On the one hand, a short two-piece 4 mm-long implant without a transmucosal portion, to be positioned at crestal level, could be developed and tested. However, peri-implant Short-term data (4 months after loading) indicate marginal bone loss was minimal (about 0.4 mm) for that 4.0 x 4.0 mm implants achieved similar results to both groups up to 1 year after loading. It may be that 8.5 x 4.0 mm-long or longer implants in the presence this minimal bone loss could be partly explained by of adequate bone volumes, however 5- to 10-years the lack of an implant-abutment junction at the level post-loading data from larger trials are necessary of the crest, which could harbour bacteria that could before reliable recommendations can be made. enhance peri-implant marginal bone loss.
Eur J Oral Implantol 2015;8(3):221–230 Esposito et al 4.0 x 4.0 mm versus longer implants in posterior jaws
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