An Up to 12-Year Retrospective Follow-Up on Immediately Loaded, Surface-Modified Implants in the Edentulous Mandible Stefan Vandeweghe, DDS, PhD;* Peter Hawker, DDS, MSc;† Hugo De Bruyn, DDS, MSc, PhD*‡
ABSTRACT Purpose: The study aims to evaluate the long-term clinical outcome of immediate loading of implants in the edentulous mandible. Materials and Methods: Patients were treated at least 1 year prior to evaluation, with four to five implants and an immediate provisional bridge in the edentulous mandible. They were invited for a clinical examination, which included the removal of the bridge, probing, perio-testing, clinical photographs, and a new radiograph to determine the bone level. Also, patients were requested to answer the OHIP-14 questionnaire to rate their satisfaction with the treatment. Results: Forty-six patients (21 men, 25 women), mean age 60 years (SD 8.5, range 43–77), were treated with 211 implants. One implant failed to integrate, resulting in a survival rate of 99.5%. After a mean follow-up of 90 months (SD 45, range 17–143), the mean bone level was 1.17 mm (SD 0.49, range 0.36–4.88). The mean Periotest value was −5.48 (SD 0.883, range −2 to −7). The mean probing depth was 2.04 mm (SD 0.71, range 1.00–8.25). There were 83.3% of the implants that demonstrated no bleeding at probing. Calculus was observed at 13.9% of the abutments. Around one implant (0.5%), suppuration was seen after probing. There was a highly significant correlation between bone loss and probing depth (p < .001). Overall, patients were very satisfied, with 69.6% scoring their treatment as excellent. Conclusion: Immediate loading of surface-enhanced implants is a highly predictable and successful treatment modality in the edentulous mandible. KEY WORDS: dental implants, edentulous mandible, immediate loading, long-term
INTRODUCTION
that dental implants could successfully integrate in a onestage approach or even be loaded the day of implant installation.3–5 This was controversial, as the early reports mentioned the presence of a fibrous tissue capsule when implants were immediately loaded, a phenomenon not observed around unloaded implants.6,7 However, Ducyk and colleagues8 reported successful osseointegration when the implants were loaded during the healing period, although static loading resulted in more bone volume and bone-to-implant contact compared with dynamic loading. This supports the theory of a critical threshold, which allows for micromotion up to 150 μm without disrupting osseointegration.9 Clinical studies have demonstrated that a predictable outcome can be achieved with immediate loading in various indications.10–15 This success is partially due to improvements of the implant design and more particularly, of its surface. The early dental implants were made of commercially pure titanium and were not subjected to any additional
Implant therapy was initiated 40 years ago and is today a widely accepted treatment modality.1,2 Although the initial protocol prescribed a submerged healing time of several months before the implants could be uncovered and loaded with a prostheses, clinical studies demonstrated *Associate professor, Department of Periodontology and Oral Implantology, Dental School, Faculty of Medicine and Health Sciences, University of Ghent, Belgium; †prosthodontist, private practitioner, Victoria Specialist Centre, Adelaide, South Australia, Australia; ‡Chairman of the department, Periodontology, Oral Implantology, Removable and Implant Prosthetics, Ghent University, Belgium and visiting professor, Department of Prosthodontics, Faculty of Odontology, Malmö University, Malmö, Sweden Corresponding Author: Dr Stefan Vandeweghe Department of periodontology, oral implantology, removable and implant prosthetics. University Hospital Ghent, De Pintelaan 185,P8 B-9000 Ghent, Belgium e-mail: [email protected] © 2015 Wiley Periodicals, Inc. DOI 10.1111/cid.12322
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chemical or physical treatments. This resulted in a turned surface with a smooth character. Several animal experiments were conducted to explore the effect of surface treatments, for example, sand- or gritblasting or acid-etching, on surface roughness and osseointegration. These preclinical studies demonstrated that a moderately rough surface resulted in higher removal torque values and increased bone apposition.16–19 Clinical studies comparing turned and roughened implants found little difference in terms of marginal bone loss or implant survival.20–23 However, in more demanding cases such as immediate loading, short implants, or compromised patients, the moderately rough implants demonstrated a better survival rate.24–27 Although the success of immediate loading with the current generation of implants has been proven through extensive research, most clinical studies are short term. Long-term data are scarce and are often based on implants that are no longer on the market. Therefore, the aim of the current study was to evaluate the long-term outcome of immediately loaded moderately rough implants in the edentulous mandible. MATERIALS AND METHODS Study Sample All patients were treated in the past by one experienced prosthodontist (P.H.) with four to five implants in the edentulous mandible. Only cases where immediate loading was performed and with at least 1-year follow-up were included in the study. No patients were excluded based on smoking habits or medical risk factors. All implants had an external hex connection and a moderately rough surface, obtained by sand-blasting and chemical cleaning (Southern Implants®, Irene, South Africa). They were installed between both mental foramina of the mandible. After abutment connection, a polyether impression was taken and within 24 hours, a metal-reinforced, screw-retained provisional bridge was connected to the implants. After 3 months, a new polyether impression (Impregum, 3M ESPE®, Seefeld, Germany) was taken to manufacture the final prosthesis, which was a screw-retained, fixed implant bride. The bridge consisted of a titanium or gold-alloy framework with acrylic denture teeth and was fixated on standard titanium abutments.
Clinical Examination In total, 68 patients were eligible to participate in the study. Of the 68, three patients died before recall and seven were lost to recall because of address changes. Of the residual 58 patients, 12 patients were not able or willing to participate, but confirmed on the telephone that everything was fine with their implants. Finally, 46 patients (67.6%) attended the clinical examination. A new radiograph was taken to determine the periimplant bone level, measured from the implantabutment interface. Patient and implant variables were collected from the patient’s file. The bridges were removed before clinical evaluation (Figure 1). Implant stability was tested using the Periotest (Medizintechnik Gulden, Modautal, Germany) device. The pocket depth was measured using a periodontal probe at four sites around the implants, and plaque and bleeding were scored using the Mombelli index.28 Also, clinical photographs were taken. The patients completed the OHIP-14 questionnaire to rate their satisfaction with the treatment. Data Analyses Radiographs were evaluated using Photoshop CS5 (Adobe®, San Jose, CA, USA). Radiographs were calibrated using the known thread pitch and implant length as a reference. Statistical calculations were were performed with SPSS v20 (IBM®, Armonk, NY, USA), with the level of significance set at p = .05. The Mann– Whitney U test was used to compare bone loss between different groups of patient and implant-related paramaters. A lineair regression was used to compare two continuous variables. RESULTS Forty-six patients (21 men, 25 women), mean age 60 years (SD 8.5, range 43–77), were treated with 210 implants. Implant dimensions and positions are depicted in Table 1 and Figure 2. Four patients still had their own teeth in the maxilla, 25 had a removable full denture, 13 had a fixed implant-supported bridge, and 4 patients had a mixture of teeth and implants. One implant failed to integrate, resulting in a survival rate of 99.5%. After a mean follow-up of 90 months (SD 45, range 17–143), the mean bone level was 1.17 mm (SD 0.49, range 0.36–4.88) (Figure 3). All implants were clinically stable. The mean Periotest value was −5.48 (SD 0.883, range −2 to −7). The width of the
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Figure 1 A, The mandibular implants were 10 years in function and immediately loaded with a provisional fixed prosthesis. B, The bridge was removed to allow proper examination and stability testing using the Periotest. C, The final prosthesis was a screw-retained bridge with resin teeth and a titanium framework. D, Very little plaque or calculus was found underneath the bridge, demonstrating the good oral hygiene of these patients.
keratinized gingiva had a mean of 1.31 mm (SD 1.11, range 0–5). In 23.9% of the cases, there was no keratinized mucosa present, but this did not affect the bone level (p = .989) (Table 2). The mean overall probing depth was 2.04 mm (SD 0.71, range 1.00–8.25). There were 83.3% of the implants that demonstrated no bleeding at probing, 14.4% showed isolated bleeding spots, 1.9% showed a confluent red margin, and 0.5% demonstrated profuse bleeding. Calculus was observed at 13.9% of the abutments. In one implant (0.5%), suppuration was seen after probing. There was a highly significant correlation between bone loss and probing depth (p < .001). Bone level was not correlated with the length of the implant (p = .871) (Table 2). There was, however, more
bone loss around the 5 mm diameter implants compared with the 4 mm diameter implants (p = .008). Patients with a removable complete denture in the maxilla experienced less peri-implant bone loss in the mandible compared with patients with an implantsupported bridge (p = .001) or a mixed dentition (p = .004). There was no significant difference in bone level between implants positioned in the anterior or posterior mandible (p = 0.848). No difference in bone level was observed between implants restored with a titanium or a gold-alloy framework (p = .940). Patient perception is depicted in Figure 4. Overall, patients were very satisfied, with 69.6% scoring their treatment as excellent, 28.3% as good, and only 2.2% were fairly satisfied with the result.
TABLE 1 Overview of the Implant Dimensions Implant length (mm)
Implant diameter (mm)
Total
4 5 6
10
11.5
13
15
18
20
Total
14 11 0 25
22 3 0 25
75 19 1 95
21 5 0 26
30 3 0 33
5 0 0 5
167 41 1 209
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Figure 2 Implant distribution according to their position in the mandible.
DISCUSSION Among clinicians and patients, dental implants are regarded as a life-long solution for missing teeth. However, the available research only goes back 40 years, to the first reports of the pilot group.29,30 Long-term reports with the Brånemark implant have demonstrated survival rates of 78% and more in the edentulous jaw31–34 and over 91% in partial cases.35–37 Pikner and colleagues34 evaluated the bone loss pattern over a 20-year period and reported a mean bone loss of 2.5 mm, which did not significantly change after the first 2 years. Although these studies demonstrate the
Figure 3 Boxplot representing the bone levels over time for each time interval. ° = outlier * = extreme value.
potential and success of dental implants, the Brånemark implant with its turned surface was eventually replaced by implants which were subjected to a surface treatment, such as the TPS implants, which promoted the osseointegration process.38 Chappuis and colleagues39 reported an 89.5% cummulative survival rate for the TPS implants after 20 years of follow-up, with 92% of the implants losing less than 1 mm of bone. Similarly, excellent results were obtained with the TiOblast surface (Astra Tech, Mölndal, Sweden) up to 16 years of followup, with survival rates ranging from 96% to 100% and limited bone loss up to 0.88 mm.40,41 However, these implant types have been discontinued and were replaced by new surface treatments. Long-term data on the current generation of implants are scarce. In a 10-year follow-up study on the Straumann SLA implant (Straumann AG, Basel, Switzerland), Buser and colleagues42 reported a 98.8% survival rate and a mean bone level of 3.32 mm from the implant shoulder to the first bone-to-implant contact. Östman and colleagues43 found a 99.2% survival rate and 0.7 mm of bone loss after 10 years for TiUnite surface implants (Nobel Biocare, Zurich, Switzerland) which is almost identical to the findings by Mozzati and colleagues,44 reporting 97.1% survival rate and 0.6 mm bone loss after 9 to 12 years of follow-up. The Southern Implants in our study had a sand-blasted and chemical-conditioned surface, which was introduced in 1992 by the company and has not been altered since. The 99.5% survival is in line with the aforementioned studies and demonstrates the longterm predictable outcome that can be achieved with these implants. The 1.17 mm of bone loss may appear to
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TABLE 2 Overview of the Implant Distribution According to Different Variables and Their Corresponding Bone Level
Gender Position Opposing dentition
Implant diameter
Keratinized tissue Frame material
Variable
n%
Mean (mm)
SD
Male Female Anterior Posterior Teeth Denture Implants Mixed 4 mm 5 mm 6 mm Present Absent Titanium Gold alloy
45 55 51.2 48.8 7.7 63.6 22.5 6.2 79.9 19.6 0.5 76.1 23.9 60.3 39.7
1.18 1.17 1.19 1.15 1.23 1.09 1.32 1.44 1.13 1.35 1.11 1.16 1.17 1.18 1.16
0.42 0.55 0.56 0.42 0.25 0.51 0.47 0.46 0.49 0.48 — 0.44 0.51 0.53 0.44
Min-max (mm)
0.36–3.01 0.38–4.88 0.36–4.88 0.46–3.01 0.81–1.61 0.36–4.88 0.48–3.01 0.90–2.63 0.36–4.88 0.65–3.01 — 0.53–2.39 0.36–4.88 0.47–4.88 0.36–2.63
p Value
0.487 0.848 0.052 0.001
0.653
0.389 0.008 0.592
0.004
0.181
0.951
0.989 0.940
A p value of .05 or less indicates a statistically significant difference.
be slighly higher when compared with the previous studies but was measured from day of surgery, and thus takes into account the initial bone loss that occurs before loading.45,46 The predictable outcome of immediate loading procedures has been reported in numerous short-term studies in various indications.11,12,46,47 Unfortunately, this short-term predictability does not guarantee the long-
Figure 4 Patient perception and satisfaction with the treatment.
term survival and stability of the implants. Animal studies have demonstrated an increased bone-toimplant contact at immediately loaded implants compared with delayed or unloaded implants.48–50 Primary stability is a prerequisite to provide immediate loading, although higher insertion torque values, over 35 Ncm, do not necessarily increase the implant survival rate and may even lower the bone-to-implant contact.48,51 There
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are a few long-term clinical studies discussing the outcome of immediate loading. Harel and colleagues52 compared immediate and delayed loaded implants after 10 years and found no significant difference in failure rate between both modalities. Degidi and colleagues53 reported 1.93 mm bone loss and a probing depth of 2.54 mm after 10 years, with 98.05% of the implants still in situ. These results support the outcome found in our study and demonstrate the predictability of immediate loading in the long run. Peri-implant health was excellent, with low plaque and bleeding levels. One factor that will affect the condition of the peri-implant tissues is the presence of keratinized mucosa. Studies have demonstrated that a lack of keratinized tissue is associated with gingival inflammation and plaque accumulation.54,55 In this study, the majority of the implants were surrounded with keratinized mucosa which might have helped to maintain health and tissue stability. Whereas early implant failure is related to nonintegration of the implant in the bone, late implant failure is often caused by overload or infection.56 Periimplantitis, in particular, is regarded as a risk factor to long-term survival of the implant, with a prevalence of 12% to 43% of the implants.57 Especially smokers and patients with a history of periodontitis are at risk,58,59 although the implant surface characteristics also play a role in the susceptibility for peri-implantitis.60,61 Implants with a smoother (turned) surface are less susceptible to peri-implantitis compared with moderately rough implants.62 In a recent study, Dierens and colleagues35 found that only 5% of turned implants demonstrated progressive bone loss after 16 to 22 years of function. Using surface-modified implants, Buser and colleagues42 reported that 1.8% of the implants showed suppuration or had evidence of peri-implantitis after 10 years. In our study, using moderately rough implants, there was only one implant that showed suppuration and progressive bone loss, and thus could be diagnosed as a peri-implantitis case. This is far below the numbers that were presented by some authors57 and corresponds more to the conclusions of the Estepona Consensus Meeting on peri-implantitis, declaring that the incidence for peri-implantitis is below 5% over 10 years.63 The influence of the dentition opposing a dental implant-supported prosthesis is still unknown. According to some studies, fixed partial dentures cause more
bone loss at implants in the opposing jaw, compared with natural teeth or removable dentures.64,65 In another study, Becktor and colleagues66 reported an almost double amount of bone loss around maxillary implants placed in grafted bone when opposed to a fixed implant bridge compared with a removable denture. Also in our study, we found less bone loss when the patient wore a removable denture in the maxilla. Patient perception is often overlooked as an outcome factor in clinical research. In this study, patients were requested to fill in the OHIP-14 questionnaire to rate their satisfaction with their fixed implant prosthesis. Overall, patients were very satisfied. Dierens and colleagues67 came to a similar conclusion, but also took baseline scores into account. Comfort, eating, speaking, and esthetics improved significantly when the provisional bridge was placed shortly after surgery. Also, patients appreciated the one-stage approach, which excludes the need for a second surgery after integration of the implants. Dolz and colleagues68 compared patient satisfaction between immediate and delayed loading, and found a significantly higher satisfaction for the first. This demonstrates that immediate loading has a significant positive effect on the patients’ life and should be considered as a treatment option, if possible. CONCLUSION Immediate loading in the edentulous mandible using surface-enhanced implants has a high survival rate and stable bone levels over time. Peri-implant health was excellent, with only one implant demonstrating signs of infection. Overall, patients were very satisfied with their treatment. REFERENCES 1. Adell R, Lekholm U, Rockler B, Branemark PI. A 15-year study of osseointegrated implants in the treatment of the edentulous jaw. Int J Oral Surg 1981; 10:387–416. 2. Schroeder A, Pohler O, Sutter F. [Tissue reaction to an implant of a titanium hollow cylinder with a titanium surface spray layer]. SSO Schweiz Monatsschr Zahnheilkd 1976; 86:713–727. 3. Collaert B, De Bruyn H. Comparison of Branemark fixture integration and short-term survival using one-stage or twostage surgery in completely and partially edentulous mandibles. Clin Oral Implants Res 1998; 9:131–135. 4. Balshi TJ, Wolfinger GJ. Immediate loading of Branemark implants in edentulous mandibles: a preliminary report. Implant Dent 1997; 6:83–88.
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43. Östman PO, Hellman M, Sennerby L. Ten years later. Results from a prospective single-centre clinical study on 121 oxidized (TiUnite) Branemark implants in 46 patients. Clin Implant Dent Relat Res 2012; 14:852–860. 44. Mozzati M, Gallesio G, Del Fabbro M. Long-term (9–12 years) outcomes of titanium implants with an oxidized surface: a retrospective investigation on 209 implants. J Oral Implantol 2013; In press. 45. Astrand P, Engquist B, Dahlgren S, Engquist E, Feldmann H, Grondahl K. Astra tech and branemark system implants: a prospective 5-year comparative study. Results after one year. Clin Implant Dent Relat Res 1999; 1:17–26. 46. Vandeweghe S, Cosyn J, Thevissen E, Van den Berghe L, De Bruyn H. A 1-year prospective study on Co-Axis implants immediately loaded with a full ceramic crown. Clin Implant Dent Relat Res 2012; 14(Suppl 1):e126–e138. 47. Vervaeke S, Collaert B, De Bruyn H. The effect of implant surface modifications on survival and bone loss of immediately loaded implants in the edentulous mandible. Int J Oral Maxillofac Implants 2013; 28:1352– 1357. 48. Rea M, Botticelli D, Ricci S, Soldini C, Gonzalez Gonzalez G, Lang NP. Influence of immediate loading on healing of implants installed with different insertion torques – an experimental study in dogs. Clin Oral Implants Res 2015; 26:90–95. 49. Romanos GE, Toh CG, Siar CH, Wicht H, Yacoob H, Nentwig GH. Bone-implant interface around titanium implants under different loading conditions: a histomorphometrical analysis in the Macaca fascicularis monkey. J Periodontol 2003; 74:1483–1490. 50. Zhang X, Duyck J, Vandamme K, Naert I, Carmeliet G. Ultrastructural characterization of the implant interface response to loading. J Dent Res 2014; 93:313–318. 51. Rizkallah N, Fischer S, Kraut RA. Correlation between insertion torque and survival rates in immediately loaded implants in the maxilla: a retrospective study. Implant Dent 2013; 22:250–254. 52. Harel N, Piek D, Livne S, Palti A, Ormianer Z. A 10-year retrospective clinical evaluation of immediately loaded tapered maxillary implants. Int J Prosthodont 2013; 26:244– 249. 53. Degidi M, Nardi D, Piattelli A. 10-year follow-up of immediately loaded implants with TiUnite porous anodized surface. Clin Implant Dent Relat Res 2012; 14: 828–838. 54. Lin GH, Chan HL, Wang HL. The significance of keratinized mucosa on implant health: a systematic review. J Periodontol 2013; 84:1755–1767. 55. Gobbato L, Avila-Ortiz G, Sohrabi K, Wang CW, Karimbux N. The effect of keratinized mucosa width on peri-implant health: a systematic review. Int J Oral Maxillofac Implants 2013; 28:1536–1545.
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56. Han HJ, Kim S, Han DH. Multifactorial evaluation of implant failure: a 19-year retrospective study. Int J Oral Maxillofac Implants 2014; 29:303–310. 57. Zitzmann NU, Berglundh T. Definition and prevalence of peri-implant diseases. J Clin Periodontol 2008; 35:286– 291. 58. Mombelli A, Muller N, Cionca N. The epidemiology of periimplantitis. Clin Oral Implants Res 2012; 23(Suppl 6):67–76. 59. Renvert S, Aghazadeh A, Hallstrom H, Persson GR. Factors related to peri-implantitis – a retrospective study. Clin Oral Implants Res 2014; 25:522–529. 60. Albouy JP, Abrahamsson I, Persson LG, Berglundh T. Implant surface characteristics influence the outcome of treatment of peri-implantitis: an experimental study in dogs. J Clin Periodontol 2011; 38:58–64. 61. Albouy JP, Abrahamsson I, Berglundh T. Spontaneous progression of experimental peri-implantitis at implants with different surface characteristics: an experimental study in dogs. J Clin Periodontol 2012; 39:182–187. 62. Berglundh T, Gotfredsen K, Zitzmann NU, Lang NP, Lindhe J. Spontaneous progression of ligature induced periimplantitis at implants with different surface roughness: an experimental study in dogs. Clin Oral Implants Res 2007; 18:655–661.
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63. Albrektsson T, Buser D, Chen ST, et al. Statements from the Estepona consensus meeting on peri-implantitis, February 2–4, 2012. Clin Implant Dent Relat Res 2012; 14:781–782. 64. Anitua E, Alkhraist MH, Pinas L, Begona L, Orive G. Implant survival and crestal bone loss around extra-short implants supporting a fixed denture: the effect of crown height space, crown-to-implant ratio, and offset placement of the prosthesis. Int J Oral Maxillofac Implants 2014; 29:682–689. 65. Pommer B, Krainhofner M, Watzek G, Tepper G, Dintsios CM. Relevance of variations in the opposing dentition for the functionality of fixed and removable partial dentures: a systematic review. Int J Dent 2012; 2012:876023. 66. Becktor JP, Eckert SE, Isaksson S, Keller EE. The influence of mandibular dentition on implant failures in bone-grafted edentulous maxillae. Int J Oral Maxillofac Implants 2002; 17:69–77. 67. Dierens M, Collaert B, Deschepper E, Browaeys H, Klinge B, De Bruyn H. Patient-centered outcome of immediately loaded implants in the rehabilitation of fully edentulous jaws. Clin Oral Implants Res 2009; 20:1070–1077. 68. Dolz J, Silverstre FJ, Montero J. Changes in general and oral health-related quality of life in immediate or conventionally loaded dental implants: a nonrandomized clinical trial. Int J Oral Maxillofac Implants 2014; 29:391–401.
ABSTRACT Purpose: The study aims to evaluate the long-term clinical outcome of immediate loading of implants in the edentulous mandible. Materials and Methods: Patients were treated at least 1 year prior to evaluation, with four to five implants and an immediate provisional bridge in the edentulous mandible. They were invited for a clinical examination, which included the removal of the bridge, probing, perio-testing, clinical photographs, and a new radiograph to determine the bone level. Also, patients were requested to answer the OHIP-14 questionnaire to rate their satisfaction with the treatment. Results: Forty-six patients (21 men, 25 women), mean age 60 years (SD 8.5, range 43–77), were treated with 211 implants. One implant failed to integrate, resulting in a survival rate of 99.5%. After a mean follow-up of 90 months (SD 45, range 17–143), the mean bone level was 1.17 mm (SD 0.49, range 0.36–4.88). The mean Periotest value was −5.48 (SD 0.883, range −2 to −7). The mean probing depth was 2.04 mm (SD 0.71, range 1.00–8.25). There were 83.3% of the implants that demonstrated no bleeding at probing. Calculus was observed at 13.9% of the abutments. Around one implant (0.5%), suppuration was seen after probing. There was a highly significant correlation between bone loss and probing depth (p < .001). Overall, patients were very satisfied, with 69.6% scoring their treatment as excellent. Conclusion: Immediate loading of surface-enhanced implants is a highly predictable and successful treatment modality in the edentulous mandible. KEY WORDS: dental implants, edentulous mandible, immediate loading, long-term
INTRODUCTION
that dental implants could successfully integrate in a onestage approach or even be loaded the day of implant installation.3–5 This was controversial, as the early reports mentioned the presence of a fibrous tissue capsule when implants were immediately loaded, a phenomenon not observed around unloaded implants.6,7 However, Ducyk and colleagues8 reported successful osseointegration when the implants were loaded during the healing period, although static loading resulted in more bone volume and bone-to-implant contact compared with dynamic loading. This supports the theory of a critical threshold, which allows for micromotion up to 150 μm without disrupting osseointegration.9 Clinical studies have demonstrated that a predictable outcome can be achieved with immediate loading in various indications.10–15 This success is partially due to improvements of the implant design and more particularly, of its surface. The early dental implants were made of commercially pure titanium and were not subjected to any additional
Implant therapy was initiated 40 years ago and is today a widely accepted treatment modality.1,2 Although the initial protocol prescribed a submerged healing time of several months before the implants could be uncovered and loaded with a prostheses, clinical studies demonstrated *Associate professor, Department of Periodontology and Oral Implantology, Dental School, Faculty of Medicine and Health Sciences, University of Ghent, Belgium; †prosthodontist, private practitioner, Victoria Specialist Centre, Adelaide, South Australia, Australia; ‡Chairman of the department, Periodontology, Oral Implantology, Removable and Implant Prosthetics, Ghent University, Belgium and visiting professor, Department of Prosthodontics, Faculty of Odontology, Malmö University, Malmö, Sweden Corresponding Author: Dr Stefan Vandeweghe Department of periodontology, oral implantology, removable and implant prosthetics. University Hospital Ghent, De Pintelaan 185,P8 B-9000 Ghent, Belgium e-mail: [email protected] © 2015 Wiley Periodicals, Inc. DOI 10.1111/cid.12322
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chemical or physical treatments. This resulted in a turned surface with a smooth character. Several animal experiments were conducted to explore the effect of surface treatments, for example, sand- or gritblasting or acid-etching, on surface roughness and osseointegration. These preclinical studies demonstrated that a moderately rough surface resulted in higher removal torque values and increased bone apposition.16–19 Clinical studies comparing turned and roughened implants found little difference in terms of marginal bone loss or implant survival.20–23 However, in more demanding cases such as immediate loading, short implants, or compromised patients, the moderately rough implants demonstrated a better survival rate.24–27 Although the success of immediate loading with the current generation of implants has been proven through extensive research, most clinical studies are short term. Long-term data are scarce and are often based on implants that are no longer on the market. Therefore, the aim of the current study was to evaluate the long-term outcome of immediately loaded moderately rough implants in the edentulous mandible. MATERIALS AND METHODS Study Sample All patients were treated in the past by one experienced prosthodontist (P.H.) with four to five implants in the edentulous mandible. Only cases where immediate loading was performed and with at least 1-year follow-up were included in the study. No patients were excluded based on smoking habits or medical risk factors. All implants had an external hex connection and a moderately rough surface, obtained by sand-blasting and chemical cleaning (Southern Implants®, Irene, South Africa). They were installed between both mental foramina of the mandible. After abutment connection, a polyether impression was taken and within 24 hours, a metal-reinforced, screw-retained provisional bridge was connected to the implants. After 3 months, a new polyether impression (Impregum, 3M ESPE®, Seefeld, Germany) was taken to manufacture the final prosthesis, which was a screw-retained, fixed implant bride. The bridge consisted of a titanium or gold-alloy framework with acrylic denture teeth and was fixated on standard titanium abutments.
Clinical Examination In total, 68 patients were eligible to participate in the study. Of the 68, three patients died before recall and seven were lost to recall because of address changes. Of the residual 58 patients, 12 patients were not able or willing to participate, but confirmed on the telephone that everything was fine with their implants. Finally, 46 patients (67.6%) attended the clinical examination. A new radiograph was taken to determine the periimplant bone level, measured from the implantabutment interface. Patient and implant variables were collected from the patient’s file. The bridges were removed before clinical evaluation (Figure 1). Implant stability was tested using the Periotest (Medizintechnik Gulden, Modautal, Germany) device. The pocket depth was measured using a periodontal probe at four sites around the implants, and plaque and bleeding were scored using the Mombelli index.28 Also, clinical photographs were taken. The patients completed the OHIP-14 questionnaire to rate their satisfaction with the treatment. Data Analyses Radiographs were evaluated using Photoshop CS5 (Adobe®, San Jose, CA, USA). Radiographs were calibrated using the known thread pitch and implant length as a reference. Statistical calculations were were performed with SPSS v20 (IBM®, Armonk, NY, USA), with the level of significance set at p = .05. The Mann– Whitney U test was used to compare bone loss between different groups of patient and implant-related paramaters. A lineair regression was used to compare two continuous variables. RESULTS Forty-six patients (21 men, 25 women), mean age 60 years (SD 8.5, range 43–77), were treated with 210 implants. Implant dimensions and positions are depicted in Table 1 and Figure 2. Four patients still had their own teeth in the maxilla, 25 had a removable full denture, 13 had a fixed implant-supported bridge, and 4 patients had a mixture of teeth and implants. One implant failed to integrate, resulting in a survival rate of 99.5%. After a mean follow-up of 90 months (SD 45, range 17–143), the mean bone level was 1.17 mm (SD 0.49, range 0.36–4.88) (Figure 3). All implants were clinically stable. The mean Periotest value was −5.48 (SD 0.883, range −2 to −7). The width of the
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Figure 1 A, The mandibular implants were 10 years in function and immediately loaded with a provisional fixed prosthesis. B, The bridge was removed to allow proper examination and stability testing using the Periotest. C, The final prosthesis was a screw-retained bridge with resin teeth and a titanium framework. D, Very little plaque or calculus was found underneath the bridge, demonstrating the good oral hygiene of these patients.
keratinized gingiva had a mean of 1.31 mm (SD 1.11, range 0–5). In 23.9% of the cases, there was no keratinized mucosa present, but this did not affect the bone level (p = .989) (Table 2). The mean overall probing depth was 2.04 mm (SD 0.71, range 1.00–8.25). There were 83.3% of the implants that demonstrated no bleeding at probing, 14.4% showed isolated bleeding spots, 1.9% showed a confluent red margin, and 0.5% demonstrated profuse bleeding. Calculus was observed at 13.9% of the abutments. In one implant (0.5%), suppuration was seen after probing. There was a highly significant correlation between bone loss and probing depth (p < .001). Bone level was not correlated with the length of the implant (p = .871) (Table 2). There was, however, more
bone loss around the 5 mm diameter implants compared with the 4 mm diameter implants (p = .008). Patients with a removable complete denture in the maxilla experienced less peri-implant bone loss in the mandible compared with patients with an implantsupported bridge (p = .001) or a mixed dentition (p = .004). There was no significant difference in bone level between implants positioned in the anterior or posterior mandible (p = 0.848). No difference in bone level was observed between implants restored with a titanium or a gold-alloy framework (p = .940). Patient perception is depicted in Figure 4. Overall, patients were very satisfied, with 69.6% scoring their treatment as excellent, 28.3% as good, and only 2.2% were fairly satisfied with the result.
TABLE 1 Overview of the Implant Dimensions Implant length (mm)
Implant diameter (mm)
Total
4 5 6
10
11.5
13
15
18
20
Total
14 11 0 25
22 3 0 25
75 19 1 95
21 5 0 26
30 3 0 33
5 0 0 5
167 41 1 209
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Figure 2 Implant distribution according to their position in the mandible.
DISCUSSION Among clinicians and patients, dental implants are regarded as a life-long solution for missing teeth. However, the available research only goes back 40 years, to the first reports of the pilot group.29,30 Long-term reports with the Brånemark implant have demonstrated survival rates of 78% and more in the edentulous jaw31–34 and over 91% in partial cases.35–37 Pikner and colleagues34 evaluated the bone loss pattern over a 20-year period and reported a mean bone loss of 2.5 mm, which did not significantly change after the first 2 years. Although these studies demonstrate the
Figure 3 Boxplot representing the bone levels over time for each time interval. ° = outlier * = extreme value.
potential and success of dental implants, the Brånemark implant with its turned surface was eventually replaced by implants which were subjected to a surface treatment, such as the TPS implants, which promoted the osseointegration process.38 Chappuis and colleagues39 reported an 89.5% cummulative survival rate for the TPS implants after 20 years of follow-up, with 92% of the implants losing less than 1 mm of bone. Similarly, excellent results were obtained with the TiOblast surface (Astra Tech, Mölndal, Sweden) up to 16 years of followup, with survival rates ranging from 96% to 100% and limited bone loss up to 0.88 mm.40,41 However, these implant types have been discontinued and were replaced by new surface treatments. Long-term data on the current generation of implants are scarce. In a 10-year follow-up study on the Straumann SLA implant (Straumann AG, Basel, Switzerland), Buser and colleagues42 reported a 98.8% survival rate and a mean bone level of 3.32 mm from the implant shoulder to the first bone-to-implant contact. Östman and colleagues43 found a 99.2% survival rate and 0.7 mm of bone loss after 10 years for TiUnite surface implants (Nobel Biocare, Zurich, Switzerland) which is almost identical to the findings by Mozzati and colleagues,44 reporting 97.1% survival rate and 0.6 mm bone loss after 9 to 12 years of follow-up. The Southern Implants in our study had a sand-blasted and chemical-conditioned surface, which was introduced in 1992 by the company and has not been altered since. The 99.5% survival is in line with the aforementioned studies and demonstrates the longterm predictable outcome that can be achieved with these implants. The 1.17 mm of bone loss may appear to
Twelve-Year Follow-Up of Surface-Modified Implants
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TABLE 2 Overview of the Implant Distribution According to Different Variables and Their Corresponding Bone Level
Gender Position Opposing dentition
Implant diameter
Keratinized tissue Frame material
Variable
n%
Mean (mm)
SD
Male Female Anterior Posterior Teeth Denture Implants Mixed 4 mm 5 mm 6 mm Present Absent Titanium Gold alloy
45 55 51.2 48.8 7.7 63.6 22.5 6.2 79.9 19.6 0.5 76.1 23.9 60.3 39.7
1.18 1.17 1.19 1.15 1.23 1.09 1.32 1.44 1.13 1.35 1.11 1.16 1.17 1.18 1.16
0.42 0.55 0.56 0.42 0.25 0.51 0.47 0.46 0.49 0.48 — 0.44 0.51 0.53 0.44
Min-max (mm)
0.36–3.01 0.38–4.88 0.36–4.88 0.46–3.01 0.81–1.61 0.36–4.88 0.48–3.01 0.90–2.63 0.36–4.88 0.65–3.01 — 0.53–2.39 0.36–4.88 0.47–4.88 0.36–2.63
p Value
0.487 0.848 0.052 0.001
0.653
0.389 0.008 0.592
0.004
0.181
0.951
0.989 0.940
A p value of .05 or less indicates a statistically significant difference.
be slighly higher when compared with the previous studies but was measured from day of surgery, and thus takes into account the initial bone loss that occurs before loading.45,46 The predictable outcome of immediate loading procedures has been reported in numerous short-term studies in various indications.11,12,46,47 Unfortunately, this short-term predictability does not guarantee the long-
Figure 4 Patient perception and satisfaction with the treatment.
term survival and stability of the implants. Animal studies have demonstrated an increased bone-toimplant contact at immediately loaded implants compared with delayed or unloaded implants.48–50 Primary stability is a prerequisite to provide immediate loading, although higher insertion torque values, over 35 Ncm, do not necessarily increase the implant survival rate and may even lower the bone-to-implant contact.48,51 There
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are a few long-term clinical studies discussing the outcome of immediate loading. Harel and colleagues52 compared immediate and delayed loaded implants after 10 years and found no significant difference in failure rate between both modalities. Degidi and colleagues53 reported 1.93 mm bone loss and a probing depth of 2.54 mm after 10 years, with 98.05% of the implants still in situ. These results support the outcome found in our study and demonstrate the predictability of immediate loading in the long run. Peri-implant health was excellent, with low plaque and bleeding levels. One factor that will affect the condition of the peri-implant tissues is the presence of keratinized mucosa. Studies have demonstrated that a lack of keratinized tissue is associated with gingival inflammation and plaque accumulation.54,55 In this study, the majority of the implants were surrounded with keratinized mucosa which might have helped to maintain health and tissue stability. Whereas early implant failure is related to nonintegration of the implant in the bone, late implant failure is often caused by overload or infection.56 Periimplantitis, in particular, is regarded as a risk factor to long-term survival of the implant, with a prevalence of 12% to 43% of the implants.57 Especially smokers and patients with a history of periodontitis are at risk,58,59 although the implant surface characteristics also play a role in the susceptibility for peri-implantitis.60,61 Implants with a smoother (turned) surface are less susceptible to peri-implantitis compared with moderately rough implants.62 In a recent study, Dierens and colleagues35 found that only 5% of turned implants demonstrated progressive bone loss after 16 to 22 years of function. Using surface-modified implants, Buser and colleagues42 reported that 1.8% of the implants showed suppuration or had evidence of peri-implantitis after 10 years. In our study, using moderately rough implants, there was only one implant that showed suppuration and progressive bone loss, and thus could be diagnosed as a peri-implantitis case. This is far below the numbers that were presented by some authors57 and corresponds more to the conclusions of the Estepona Consensus Meeting on peri-implantitis, declaring that the incidence for peri-implantitis is below 5% over 10 years.63 The influence of the dentition opposing a dental implant-supported prosthesis is still unknown. According to some studies, fixed partial dentures cause more
bone loss at implants in the opposing jaw, compared with natural teeth or removable dentures.64,65 In another study, Becktor and colleagues66 reported an almost double amount of bone loss around maxillary implants placed in grafted bone when opposed to a fixed implant bridge compared with a removable denture. Also in our study, we found less bone loss when the patient wore a removable denture in the maxilla. Patient perception is often overlooked as an outcome factor in clinical research. In this study, patients were requested to fill in the OHIP-14 questionnaire to rate their satisfaction with their fixed implant prosthesis. Overall, patients were very satisfied. Dierens and colleagues67 came to a similar conclusion, but also took baseline scores into account. Comfort, eating, speaking, and esthetics improved significantly when the provisional bridge was placed shortly after surgery. Also, patients appreciated the one-stage approach, which excludes the need for a second surgery after integration of the implants. Dolz and colleagues68 compared patient satisfaction between immediate and delayed loading, and found a significantly higher satisfaction for the first. This demonstrates that immediate loading has a significant positive effect on the patients’ life and should be considered as a treatment option, if possible. CONCLUSION Immediate loading in the edentulous mandible using surface-enhanced implants has a high survival rate and stable bone levels over time. Peri-implant health was excellent, with only one implant demonstrating signs of infection. Overall, patients were very satisfied with their treatment. REFERENCES 1. Adell R, Lekholm U, Rockler B, Branemark PI. A 15-year study of osseointegrated implants in the treatment of the edentulous jaw. Int J Oral Surg 1981; 10:387–416. 2. Schroeder A, Pohler O, Sutter F. [Tissue reaction to an implant of a titanium hollow cylinder with a titanium surface spray layer]. SSO Schweiz Monatsschr Zahnheilkd 1976; 86:713–727. 3. Collaert B, De Bruyn H. Comparison of Branemark fixture integration and short-term survival using one-stage or twostage surgery in completely and partially edentulous mandibles. Clin Oral Implants Res 1998; 9:131–135. 4. Balshi TJ, Wolfinger GJ. Immediate loading of Branemark implants in edentulous mandibles: a preliminary report. Implant Dent 1997; 6:83–88.
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5. Randow K, Ericsson I, Nilner K, Petersson A, Glantz PO. Immediate functional loading of Branemark dental implants. An 18-month clinical follow-up study. Clin Oral Implants Res 1999; 10:8–15. 6. Brunski JB, Moccia AF Jr, Pollack SR, Korostoff E, Trachtenberg DI. The influence of functional use of endosseous dental implants on the tissue-implant interface. II. Clinical aspects. J Dent Res 1979; 58:1970–1980. 7. Brunski JB, Moccia AF Jr, Pollack SR, Korostoff E, Trachtenberg DI. The influence of functional use of endosseous dental implants on the tissue-implant interface. I. Histological aspects. J Dent Res 1979; 58:1953– 1969. 8. Duyck J, Ronold HJ, Van Oosterwyck H, Naert I, Vander Sloten J, Ellingsen JE. The influence of static and dynamic loading on marginal bone reactions around osseointegrated implants: an animal experimental study. Clin Oral Implants Res 2001; 12:207–218. 9. Szmukler-Moncler S, Salama H, Reingewirtz Y, Dubruille JH. Timing of loading and effect of micromotion on bone-dental implant interface: review of experimental literature. J Biomed Mater Res 1998; 43:192–203. 10. Browaeys H, Dierens M, Ruyffelaert C, Matthijs C, De Bruyn H, Vandeweghe S. Ongoing crestal bone loss around implants subjected to computer-guided flapless surgery and immediate loading using the All-on-4® concept. Clin Implant Dent Relat Res 2014; In press. 11. Collaert B, De Bruyn H. Immediate functional loading of TiOblast dental implants in full-arch edentulous maxillae: a 3-year prospective study. Clin Oral Implants Res 2008; 19:1254–1260. 12. De Bruyn H, Van de Velde T, Collaert B. Immediate functional loading of TiOblast dental implants in full-arch edentulous mandibles: a 3-year prospective study. Clin Oral Implants Res 2008; 19:717–723. 13. Östman P-O, Wennerberg A, Ekestubbe A, Albrektsson T. Immediate occlusal loading of Nanotite tapered implants: a prospective 1-year clinical and radiographic study. Clin Implant Dent Relat Res 2013 Dec; 15(6):809–818. 14. Testori T, Meltzer A, Del Fabbro M, et al. Immediate occlusal loading of Osseotite implants in the lower edentulous jaw. A multicenter prospective study. Clin Oral Implants Res 2004; 15:278–284. 15. Vandeweghe S, Cosyn J, Thevissen E, Van den Berghe L, De Bruyn H. A 1-year prospective study on Co-Axis implants immediately loaded with a full ceramic crown. Clin Implant Dent Relat Res 2012; 14(Suppl 1):e126–e138. 16. Buser D, Schenk R, Steinemann S, Fiorellini J, Fox C, Stich H. Influence of surface characteristics on bone integration of titanium implants. A histomorphometric study in miniature pigs. J Biomed Mater Res 1991; 25:889–902. 17. Klokkevold PR, Nishimura RD, Adachi M, Caputo A. Osseointegration enhanced by chemical etching of the tita-
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