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British Journal of Oral and Maxillofacial Surgery 52 (2014) 149–153
Clinical analysis of the stability of dental implants after preparation of the site by conventional drilling or piezosurgery Ulisses Tavares da Silva Neto a , Julio Cesar Joly b , Sergio Alexandre Gehrke c,∗ a b c
Postgraduate Program in Implantology of APCD, Jundiaí and Osasco, Brazil São Leopoldo Mandic University, Campinas, Brazil Catholic University of Uruguay, Montevideo, Uruguay
Accepted 28 October 2013 Available online 20 November 2013
Abstract We used resonance frequency analysis to evaluate the implant stability quotient (ISQ) of dental implants that were installed in sites prepared by either conventional drilling or piezoelectric tips. We studied 30 patients with bilateral edentulous areas in the maxillary premolar region who were randomised to have the implant inserted with conventional drilling, or with piezoelectric surgery. The stability of each implant was measured by resonance frequency analysis immediately after placement to assess the immediate stability (time 1) and again at 90 days (time 2) and 150 days (time 3). In the conventional group the mean (SD) ISQ for time 1 was 69.1 (6.1) (95% CI 52.4–77.3); for time 2, 70.7 (5.7) (95% CI 60.4–82.8); and for time 3, 71.7 (4.5) (95% CI 64.2–79.2). In the piezosurgery group the corresponding values were: 77.5 (4.6) (95% CI 71.1–84.3) for time 1, 77.0 (4.2) (95% CI, 69.7–85.2) for time 2, and 79.1 (3.1) (95% CI 74.5–87.3) for time 3. The results showed significant increases in the ISQ values for the piezosurgery group at each time point (p = 0.04). The stability of implants placed using the piezoelectric method was greater than that of implants placed using the conventional technique. © 2013 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Keywords: Implant stability; Resonance frequency analysis; Piezosurgery; Conventional drilling; Implant osteotomies
Introduction Improvements in the bioengineering, geometry, and surfaces of implants, together with the advent of minimally invasive surgical techniques with increased tissue preservation, have changed the method of placement of dental implants, and allowed clinicians to obtain better results. Stability is a prerequisite for the long-term clinical success of implants, and it depends on the quantity and quality of local bone, the design of the implant, and the surgical technique ∗ Corresponding author at: Rua Dr. Bozano, 571, 97015-001 Santa Maria (RS), Brazil. Tel.: +55 55 3222 7253; fax: +55 55 3222 7253. E-mail addresses: [email protected] (U.T. da Silva Neto), [email protected] (J.C. Joly), [email protected] (S.A. Gehrke).
used (subinstrumentation or overinstrumentation).1 The changes during tissue healing, such as resorption of bone and integration of the bone–implant interface, can govern the degree of secondary stability of the implant. Obviously the healing process will be affected by the morphology of the bone including the trabecular pattern, the density, and the degree of maturation.2 Rotary drills are efficient but they have several disadvantages, including the generation of debris and chips (which can spread and produce foreign-body reactions), the creation of substantial haematomata at the drilling site, the production of heat, difficulties in attaining geometrical accuracy, and wobbling.3–5 Osteotomies designed to prepare the bony bed for placement of an implant generate heat, mainly from the high pressure manual movements and the speed of the rotary instrumentation that is required to achieve more
0266-4356/$ – see front matter © 2013 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bjoms.2013.10.008
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efficient cutting. If it is not controlled this heat can lead to osteonecrosis.5,6 A more recent option is piezosurgery (rather than traditional drills) for osteotomy. Piezosurgery (piezoelectric bone surgery) is a promising, precise, bone-cutting system that is based on ultrasonic microvibrations and spares soft tissue. This allows for the selective cutting of bone, and causes minimal trauma at the time of the operation7 because any cuts are micrometric and selective, and most damage is limited to the surrounding tissues.8,9 Not only is this technique clinically effective, but histological and histomorphometric observation of postoperative wound healing and formation of bone in experimental animal models has indicated that the response of tissue is more favourable after piezosurgery10 than after conventional bone-cutting techniques with diamond or carbide rotary instruments.11 The aim of this study was to evaluate in a randomised controlled clinical study the stability of implants placed in osteotomies made with conventional drilling or with the piezoelectric method at 3 different time points: immediately afterwards, and 90 days and 150 days after implantation.
Patients and methods Thirty patients (24 women and 6 men aged between 20 and 60 years) were selected for this study, which was approved by the Ethics and Research Committee of São Leopoldo Mandic University (Campinas, Brazil). All patients were informed of the nature of the study and gave written consent to participation according to the Helsinki Declaration of 1994. The inclusion criteria included the patient’ current stable medical condition, the ability to withstand the stress of a dental implant, and the request for implants in the maxillary premolar area. Included patients were required to have had at least 6 months of healing without any grafting at the time of, or after, the extractions. Patients with unstable systemic conditions such as diabetes, hypertension, or osteoporosis; patients with oral disease in their soft or hard tissues; and patients with harmful oral habits such as bruxism and smoking, were not included. Exclusion criteria also included the presence of uncontrolled or untreated periodontal disease, insufficient bony volume to insert implants without augmentation procedures (a crest of at least 13 mm in height and 5 mm in width was required) and an insufficient mesiodistal space.
A full-thickness mucoperiostal flap was raised, and the underlying alveolar bone exposed for osteotomy. The adjacent implant sites were prepared in each patient during the same operation. At the control site the osteotomies were made using the conventional drilling method (according to the manufacturer’s instructions), while in the test site the osteotomies were produced using piezoelectric surgery. Sixty-eight conical implants (n = 34 in each group), with a double-sandblasted and acid-treated surface and a Morse taper connection (Neodent, Curitiba, Brazil) were inserted. Implants were always inserted on one side for the conventional drilling and on the opposite side for the piezoelectric method, selected randomly. All implants were 3.5 mm in diameter and 13 mm long. The torque of the implants was limited to 55 Nm. For implants placed by conventional techniques we used stainless steel and diamond piezoelectric tips with diameters of 2 mm, 2.5 mm, and 3 mm (Fig. 1A) with a piezosonic device (Driller, São Paulo, Brazil) and external irrigation with 0.9%saline solution. In the piezosurgery group we used a motor Kavo Concept (KaVo Dental GmbH, Biberach, Germany) and counter angle Kavo with a 27:1 reduction and an external irrigation with 0.9% saline solution. All implants were installed with the use of surgical guides, and the wounds were sutured. Ketoprofen 200 mg/day and paracetamol 750 mg 3 times a day were given for pain relief for 3 days postoperatively. All implants were submerged for 90 days, and with the healing abutment for 150 days. Restorative procedures were done during the 90 and 150 days. Implants were inserted to analyse the resonance frequency in both sides using the OstellTM Mentor (Integration Diagnostics AB, Göteborg, Sweden) for the measurements of resonance frequency analysis. A SmartpegTM (Integration Diagnostics AB, Göteborg, Sweden) was screwed into each implant and tightened to approximately 5 Ncm. The transducer probe was aimed at the small magnet at the top of the Smartpeg at a distance of 2 or 3 mm and held stable during the pulsing until the instrument beeped and displayed the ISQ value. The ISQ values were measured during the operation (time 1), at 90 days (time 2), and at 150 days (time 3) postoperatively (Fig. 2). The measurements were taken twice in the buccolingual direction and twice in the mesiodistal direction.12 The mean of the 2 measurements from each direction was regarded as the representative ISQ in that direction. The higher values of buccolingual and mesiodistal ISQ were used to generate a mean value, and all values were recorded. In addition, each implant was evaluated at all visits for mobility, pain, and signs of infection.
Surgical technique Statistical analysis Patients were given amoxicillin 875 mg orally twice a day for 5 days, and the initial dose of 2 g was given 2 h before operation. All procedures were done under local anaesthesia with 2% articaíne (Dfl Ltda, Rio de Janeiro, Brazil), as day cases by the same surgeon, who was familiar with both traditional and piezoelectric surgical techniques.
The outcomes were analysed longitudinally within the same group using the analysis of variance (ANOVA) test for repeated measures. The significance of differences between the 2 groups was assessed using Student’s t test for unpaired samples (R Software version 2.6.2, R Foundation for
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Fig. 1. Piezoelectric tips: (A) pilot = 2 mm, 2.5 mm, and 3 mm in diameter, respectively. Conventional drills for conical implants and (B) pilot = 2 mm and 3 mm in diameter, respectively.
there was a significant increase in the level of stability at time 2 compared with that at time 3 (p = 0.0001). In the conventional group there was a more gradual increase in stability, which was more noticeable between times 1 and 3. When we compared the ISQ across the same times, the piezosurgery group consistently had better stability than the conventional group (Fig. 4).
Discussion
Fig. 2. Positioned smart peg showing the measurement of the implant stability quotient with the OstellTM Mentor.
Statistical Computing, Wien, Austria). Probabilities of less than 0.05 were accepted as significant.
Results Four patients presented with none of the 4 upper maxillary premolars, and 26 patients were missing 1 upper premolar bilaterally. All implants survived and were well osseointegrated. No patients dropped out of the study during the observation period. One hundred and fifty days after insertion, 68 of the implants were osseointegrated. Fig. 3 shows a box-plot of the ISQ of each evaluation time for each group and shows that in the conventional group there was more variation between the minimum and maximum values obtained at all times proposed, while in the peizosurgery group there was less variation. The piezosurgery group therefore had a significantly higher mean stability than the conventional group (p < 0.001), regardless of the time of evaluation (p = 0.05). It was not possible to identify significant differences within the groups between time 1 and time 2 (conventional group: p = 0.07; piezosurgery group: p = 0.86). In the piezosurgery group
The aim of this study was to evaluate longitudinally changes in the stability of implants inserted in sites prepared with rotary or piezosurgery techniques. In both conventional drilling and piezoelectric osteotomies, care must be taken to minimise thermal damage to tissues by controlling irrigation and cooling the bony tissue.8,13 Several authors have reported that surface necrosis after coagulation in rotary drilling also ruptures the vasculature at the drilling site. Substantial haematomas have been found around the sites of rotary drilling in animal studies.14 The use of piezoelectric osteotomy seems to simplify the procedure and reduce intraoperative complications. Postoperative results suggest that osteotomies have a decreased risk of complications if care is taken in the heating of the bony structure during operations.13,15 This study therefore aimed to find out if lesser degrees of trauma during the preparation of bone for placement of implants could improve the stability of the implants and their subsequent osseointregration. The piezoelectric technique was introduced to overcome several of the limitations involved in conventional osteotomies.16 The use of an ultrasonic device decreased the difficulty in cutting thin or delicate bone structures, as it can easily cut with great precision.16 It has also been shown that the implantation of implants in areas of thick bone with a small alveolar ridge-shaped blade was facilitated by the use of piezoelectric tips, which have a delicate and precise cut without a rotating effect, compared with conventional drilling.7,17 At present, cutting efficiency with conventional drilling typically requires a good grip and manual pressure, which often leads to bony fenestration as a result of the effects of rotation
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Fig. 3. Box plot showing the degree of stability (implant stability quotient) for each assessment time for each group. Group 1 = conventional surgery, group 2 = piezosurgery.
Fig. 4. Histogram comparing mean (SD) between the groups at each time point (p = 0.04). Group 1 = conventional surgery, group 2 = piezosurgery.
and atrophic alveolar bone. The results in Fig. 3 show that we can deduce that drilling by the piezoelectric method is more accurate than the traditional method, as the variation in minimum and maximum ISQs was more uniform in the piezosurgery group. Clinical methods commonly used to assess implant stability and osseointegration include percussion, mobility tests, and radiographs. All these methods are limited by their lack of standardisation, poor sensitivity, and susceptibility to operator-associated variables.18–20 Recently, a modern and uninvasive diagnostic technique called resonance frequency analysis has been used for the evaluation and measurement of the stability of implants within bone. The reasons to use
this technique are that it is rapid, straightforward, and easy to accomplish as part of routine clinical procedure, and there is no risk of discomfort to the patient. ISQ indices that have been analysed showed a continued increase in stability, although it was still below that of the piezoelectric group. The success of the piezoelectric technique may be related to the accommodation of the bone after compression during installation of the implant and more favourable biological changes in early remodelling of the bone. Because this method is more delicate, it could have considerable benefits for bone healing.21 In addition, for the conventional drilling technique, the mean ISQ over the 3 time points for the conventional drilling technique followed
U.T. da Silva Neto et al. / British Journal of Oral and Maxillofacial Surgery 52 (2014) 149–153
a gradual increase (that was almost linear), whereas for the piezoelectric method, the mean. ISQ during the 3 time points followed a different pattern: although it was higher in the first measurement, it remained at essentially the same level during the second measurement and increased significantly only after 150 days at the time of the third measurement. After 150 days, the values of ISQ for the piezoelectric method were higher than those for the conventional drilling method. The probable explanation is that in the last period of bone remodelling the values gradually increased as the bone repaired and were favoured by factors that benefited this gradual increase.22 Some authors found that the ISQ in regular driller holes continued increasing after 12 months of immediate loading, but described little difference between 3 and 6 months.18 In the present study there was an increase in the ISQ between the periods 90 and 150 days, probably as a result of movement during manoeuvres and procedures for the preparation of rehabilitation (healing abutment, transfer, or prosthetic abutment), which generate loads of low frequency and low intensity. Preliminary data have suggested that ISQ measures of up to 60–65 at the time of insertion of the implant predict a good prognosis for immediate implant loading.23 In the present series the values were almost always higher than this, suggesting that the development of immediate loading protocols after the piezoelectric method of installation could be developed in the near future. These results are of practical importance to increase predictability in cases of immediate loading, for example. To date, millions of dental implants have been successfully placed using a conventional drilling approach; however, this technique is less suitable for high-risk patients such as those who require placement of implants in irradiated bone. The results obtained in this study show the advantages of the piezosurgical technique for osteotomies, and additional future research should be conducted in this promising area of study. It should include long-term monitoring, particularly after loading the implants, and should be designed to assess the possible similarity in ISQs between the 2 methods.
References 1. Friberg B, Sennerby L, Linden B, Gröndahl K, Lekholm U. Stability measurements o f one-stage Branemark implants during healing in mandibles. A clinical resonance frequency analysis study. Int J Oral Maxillofac Surg 1999;28:266–72. 2. Zix J, Hug S, Kessler-Liechti G, Mericske-Stern R. Measurement of dental implant stability by resonance frequency analysis and damping capacity assessment: comparison of both techniques in a clinical trial. Int J Oral Maxillofac Implants 2008;23:525–30. 3. Saha S, Pal S, Albright JA. Surgical drilling: design and performance of an improved drill. J Biomech Eng 1982;104:245–52. 4. Wiggins KL, Malkin S. Drilling of bone. J Biomech 1976;9:553–9.
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5. Gehrke SA, Neto HL, Mardegan FE. Investigation of the effect of movement and irrigation systems on temperature in the conventional drilling of cortical bone. Br J Oral Maxillofac Surg 2013. 6. Augustin G, Zigman T, Davila S, et al. Cortical bone drilling and thermal osteonecrosis. Clin Biomech (Bristol, Avon) 2012;27(4):313–25. 7. Labanca M, Azzola F, Vinci R, Rodella L. Piezoelectric surgery: twenty years of use. Br J Oral Maxillofac Surg 2008;46:265–9. 8. Covani U, Barone A. Piezosurgical treatment of unicystic ameloblastoma. J Periodontol 2007;78:1342–7. 9. Gleizal A, Béra JC, Lavandier B, Béziat JL. Piezoelectric osteotomy: a new technique for bone surgery—advantages in craniofacial surgery. Childs Nerv Syst 2007;23:509–13. 10. Chiriac G, Herten M, Schwarz F, Rothmel D, Becker J. Autogenous bone chips: influence of a new piezoelectric device (piezosurgery) on chip morphology, cell viability and differentiation. J Clin Periodontol 2005;32:994–9. 11. Vercellotti T, Nevins ML, Kim DM, et al. Osseous response following resective therapy with piezosurgery. Int J Periodont Restor Dent 2005;25:543–9. 12. Sim CP, Lang NP. Factors influencing resonance frequency analysis assessed by Osstell mentor during implant tissue integration: I. Instrument positioning, bone structure, implant length. Clin Oral Implants Res 2010;21:598–604. 13. Sivolella S, Berengo M, Scarin M, Mella F, Martinelli F. Autogenous particulate bone collected with a piezo-electric surgical device and bone trap: a microbiological and histomorphometric study. Arch Oral Biol 2006;51:883–91. 14. Harder S, Wolfart S, Mehl C, Kern M. Performance of ultrasonic devices for bone surgery and associated intrasseous temperature development. Int J Oral Maxillofac Implants 2009;24:484–90. 15. González-García A, Diniz-Freitas M, Somoza-Martín M, García-García A. Piezoelectric and conventional osteotomy in alveolar distraction osteogenesis in a series of 17 patients. Int J Oral Maxillofac Implants 2008;23:891–6. 16. Preti G, Martinasso G, Peirone B, et al. Cytokines and growth factors involved in the osseointegration of oral titanium implants positioned using piezoelectric bone surgery versus a drill technique: a pilot study in minipigs. J Periodontol 2007;78:716–22. 17. Eggers G, Klein J, Blank J, Hassfeld S. Piezosurgery: an ultrasound device for cutting bone and its use and limitations in maxillofacial surgery. Br J Oral Maxillofac Surg 2004;42:451–3. 18. Fischer K, Bäckström M, Sennerby L. Immediate and early loading of oxidized tapered implants in the partially edentulous maxilla: a 1year prospective clinical, radiographic, and resonance frequency analysis study. Clin Implant Dent Relat Res 2009;11:69–80. 19. Meredith N, Book K, Friberg B, Jemt T, Sennerby L. Resonance frequency measurements of implants stability in vivo. A cross-sectional and longitudinal study of resonance frequency measurements on implant in the edentulous and partially dentate maxilla. Clin Oral Implants Res 1997;8:226–33. 20. Meredith N, Shagaldi F, Alleyne D, Sennerby L, Cawley P. The application of resonance frequency measurements to study the stability of titanium implants during healing in the rabbit tibia. Clin Oral Implants Res 1997;8:234–43. 21. Maurer P, Kriwalsky MS, Block Veras R, Brandt J, Heiss C. Light microscopic examination of rabbit skulls following conventional and piezosurgery osteotomy (in German). Biomed Tech (Berl) 2007;52:351–5. 22. Meredith N. Assessment of implant stability as a prognostic determinant. Int J Prosthodont 1998;11:491–550. 23. Sennerby L, Meredith N. Resonance frequency analysis: measuring implant stability and osseointregation. Compend Contin Educ Dent 1998;19:493–504.
British Journal of Oral and Maxillofacial Surgery 52 (2014) 149–153
Clinical analysis of the stability of dental implants after preparation of the site by conventional drilling or piezosurgery Ulisses Tavares da Silva Neto a , Julio Cesar Joly b , Sergio Alexandre Gehrke c,∗ a b c
Postgraduate Program in Implantology of APCD, Jundiaí and Osasco, Brazil São Leopoldo Mandic University, Campinas, Brazil Catholic University of Uruguay, Montevideo, Uruguay
Accepted 28 October 2013 Available online 20 November 2013
Abstract We used resonance frequency analysis to evaluate the implant stability quotient (ISQ) of dental implants that were installed in sites prepared by either conventional drilling or piezoelectric tips. We studied 30 patients with bilateral edentulous areas in the maxillary premolar region who were randomised to have the implant inserted with conventional drilling, or with piezoelectric surgery. The stability of each implant was measured by resonance frequency analysis immediately after placement to assess the immediate stability (time 1) and again at 90 days (time 2) and 150 days (time 3). In the conventional group the mean (SD) ISQ for time 1 was 69.1 (6.1) (95% CI 52.4–77.3); for time 2, 70.7 (5.7) (95% CI 60.4–82.8); and for time 3, 71.7 (4.5) (95% CI 64.2–79.2). In the piezosurgery group the corresponding values were: 77.5 (4.6) (95% CI 71.1–84.3) for time 1, 77.0 (4.2) (95% CI, 69.7–85.2) for time 2, and 79.1 (3.1) (95% CI 74.5–87.3) for time 3. The results showed significant increases in the ISQ values for the piezosurgery group at each time point (p = 0.04). The stability of implants placed using the piezoelectric method was greater than that of implants placed using the conventional technique. © 2013 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Keywords: Implant stability; Resonance frequency analysis; Piezosurgery; Conventional drilling; Implant osteotomies
Introduction Improvements in the bioengineering, geometry, and surfaces of implants, together with the advent of minimally invasive surgical techniques with increased tissue preservation, have changed the method of placement of dental implants, and allowed clinicians to obtain better results. Stability is a prerequisite for the long-term clinical success of implants, and it depends on the quantity and quality of local bone, the design of the implant, and the surgical technique ∗ Corresponding author at: Rua Dr. Bozano, 571, 97015-001 Santa Maria (RS), Brazil. Tel.: +55 55 3222 7253; fax: +55 55 3222 7253. E-mail addresses: [email protected] (U.T. da Silva Neto), [email protected] (J.C. Joly), [email protected] (S.A. Gehrke).
used (subinstrumentation or overinstrumentation).1 The changes during tissue healing, such as resorption of bone and integration of the bone–implant interface, can govern the degree of secondary stability of the implant. Obviously the healing process will be affected by the morphology of the bone including the trabecular pattern, the density, and the degree of maturation.2 Rotary drills are efficient but they have several disadvantages, including the generation of debris and chips (which can spread and produce foreign-body reactions), the creation of substantial haematomata at the drilling site, the production of heat, difficulties in attaining geometrical accuracy, and wobbling.3–5 Osteotomies designed to prepare the bony bed for placement of an implant generate heat, mainly from the high pressure manual movements and the speed of the rotary instrumentation that is required to achieve more
0266-4356/$ – see front matter © 2013 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bjoms.2013.10.008
150
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efficient cutting. If it is not controlled this heat can lead to osteonecrosis.5,6 A more recent option is piezosurgery (rather than traditional drills) for osteotomy. Piezosurgery (piezoelectric bone surgery) is a promising, precise, bone-cutting system that is based on ultrasonic microvibrations and spares soft tissue. This allows for the selective cutting of bone, and causes minimal trauma at the time of the operation7 because any cuts are micrometric and selective, and most damage is limited to the surrounding tissues.8,9 Not only is this technique clinically effective, but histological and histomorphometric observation of postoperative wound healing and formation of bone in experimental animal models has indicated that the response of tissue is more favourable after piezosurgery10 than after conventional bone-cutting techniques with diamond or carbide rotary instruments.11 The aim of this study was to evaluate in a randomised controlled clinical study the stability of implants placed in osteotomies made with conventional drilling or with the piezoelectric method at 3 different time points: immediately afterwards, and 90 days and 150 days after implantation.
Patients and methods Thirty patients (24 women and 6 men aged between 20 and 60 years) were selected for this study, which was approved by the Ethics and Research Committee of São Leopoldo Mandic University (Campinas, Brazil). All patients were informed of the nature of the study and gave written consent to participation according to the Helsinki Declaration of 1994. The inclusion criteria included the patient’ current stable medical condition, the ability to withstand the stress of a dental implant, and the request for implants in the maxillary premolar area. Included patients were required to have had at least 6 months of healing without any grafting at the time of, or after, the extractions. Patients with unstable systemic conditions such as diabetes, hypertension, or osteoporosis; patients with oral disease in their soft or hard tissues; and patients with harmful oral habits such as bruxism and smoking, were not included. Exclusion criteria also included the presence of uncontrolled or untreated periodontal disease, insufficient bony volume to insert implants without augmentation procedures (a crest of at least 13 mm in height and 5 mm in width was required) and an insufficient mesiodistal space.
A full-thickness mucoperiostal flap was raised, and the underlying alveolar bone exposed for osteotomy. The adjacent implant sites were prepared in each patient during the same operation. At the control site the osteotomies were made using the conventional drilling method (according to the manufacturer’s instructions), while in the test site the osteotomies were produced using piezoelectric surgery. Sixty-eight conical implants (n = 34 in each group), with a double-sandblasted and acid-treated surface and a Morse taper connection (Neodent, Curitiba, Brazil) were inserted. Implants were always inserted on one side for the conventional drilling and on the opposite side for the piezoelectric method, selected randomly. All implants were 3.5 mm in diameter and 13 mm long. The torque of the implants was limited to 55 Nm. For implants placed by conventional techniques we used stainless steel and diamond piezoelectric tips with diameters of 2 mm, 2.5 mm, and 3 mm (Fig. 1A) with a piezosonic device (Driller, São Paulo, Brazil) and external irrigation with 0.9%saline solution. In the piezosurgery group we used a motor Kavo Concept (KaVo Dental GmbH, Biberach, Germany) and counter angle Kavo with a 27:1 reduction and an external irrigation with 0.9% saline solution. All implants were installed with the use of surgical guides, and the wounds were sutured. Ketoprofen 200 mg/day and paracetamol 750 mg 3 times a day were given for pain relief for 3 days postoperatively. All implants were submerged for 90 days, and with the healing abutment for 150 days. Restorative procedures were done during the 90 and 150 days. Implants were inserted to analyse the resonance frequency in both sides using the OstellTM Mentor (Integration Diagnostics AB, Göteborg, Sweden) for the measurements of resonance frequency analysis. A SmartpegTM (Integration Diagnostics AB, Göteborg, Sweden) was screwed into each implant and tightened to approximately 5 Ncm. The transducer probe was aimed at the small magnet at the top of the Smartpeg at a distance of 2 or 3 mm and held stable during the pulsing until the instrument beeped and displayed the ISQ value. The ISQ values were measured during the operation (time 1), at 90 days (time 2), and at 150 days (time 3) postoperatively (Fig. 2). The measurements were taken twice in the buccolingual direction and twice in the mesiodistal direction.12 The mean of the 2 measurements from each direction was regarded as the representative ISQ in that direction. The higher values of buccolingual and mesiodistal ISQ were used to generate a mean value, and all values were recorded. In addition, each implant was evaluated at all visits for mobility, pain, and signs of infection.
Surgical technique Statistical analysis Patients were given amoxicillin 875 mg orally twice a day for 5 days, and the initial dose of 2 g was given 2 h before operation. All procedures were done under local anaesthesia with 2% articaíne (Dfl Ltda, Rio de Janeiro, Brazil), as day cases by the same surgeon, who was familiar with both traditional and piezoelectric surgical techniques.
The outcomes were analysed longitudinally within the same group using the analysis of variance (ANOVA) test for repeated measures. The significance of differences between the 2 groups was assessed using Student’s t test for unpaired samples (R Software version 2.6.2, R Foundation for
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151
Fig. 1. Piezoelectric tips: (A) pilot = 2 mm, 2.5 mm, and 3 mm in diameter, respectively. Conventional drills for conical implants and (B) pilot = 2 mm and 3 mm in diameter, respectively.
there was a significant increase in the level of stability at time 2 compared with that at time 3 (p = 0.0001). In the conventional group there was a more gradual increase in stability, which was more noticeable between times 1 and 3. When we compared the ISQ across the same times, the piezosurgery group consistently had better stability than the conventional group (Fig. 4).
Discussion
Fig. 2. Positioned smart peg showing the measurement of the implant stability quotient with the OstellTM Mentor.
Statistical Computing, Wien, Austria). Probabilities of less than 0.05 were accepted as significant.
Results Four patients presented with none of the 4 upper maxillary premolars, and 26 patients were missing 1 upper premolar bilaterally. All implants survived and were well osseointegrated. No patients dropped out of the study during the observation period. One hundred and fifty days after insertion, 68 of the implants were osseointegrated. Fig. 3 shows a box-plot of the ISQ of each evaluation time for each group and shows that in the conventional group there was more variation between the minimum and maximum values obtained at all times proposed, while in the peizosurgery group there was less variation. The piezosurgery group therefore had a significantly higher mean stability than the conventional group (p < 0.001), regardless of the time of evaluation (p = 0.05). It was not possible to identify significant differences within the groups between time 1 and time 2 (conventional group: p = 0.07; piezosurgery group: p = 0.86). In the piezosurgery group
The aim of this study was to evaluate longitudinally changes in the stability of implants inserted in sites prepared with rotary or piezosurgery techniques. In both conventional drilling and piezoelectric osteotomies, care must be taken to minimise thermal damage to tissues by controlling irrigation and cooling the bony tissue.8,13 Several authors have reported that surface necrosis after coagulation in rotary drilling also ruptures the vasculature at the drilling site. Substantial haematomas have been found around the sites of rotary drilling in animal studies.14 The use of piezoelectric osteotomy seems to simplify the procedure and reduce intraoperative complications. Postoperative results suggest that osteotomies have a decreased risk of complications if care is taken in the heating of the bony structure during operations.13,15 This study therefore aimed to find out if lesser degrees of trauma during the preparation of bone for placement of implants could improve the stability of the implants and their subsequent osseointregration. The piezoelectric technique was introduced to overcome several of the limitations involved in conventional osteotomies.16 The use of an ultrasonic device decreased the difficulty in cutting thin or delicate bone structures, as it can easily cut with great precision.16 It has also been shown that the implantation of implants in areas of thick bone with a small alveolar ridge-shaped blade was facilitated by the use of piezoelectric tips, which have a delicate and precise cut without a rotating effect, compared with conventional drilling.7,17 At present, cutting efficiency with conventional drilling typically requires a good grip and manual pressure, which often leads to bony fenestration as a result of the effects of rotation
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Fig. 3. Box plot showing the degree of stability (implant stability quotient) for each assessment time for each group. Group 1 = conventional surgery, group 2 = piezosurgery.
Fig. 4. Histogram comparing mean (SD) between the groups at each time point (p = 0.04). Group 1 = conventional surgery, group 2 = piezosurgery.
and atrophic alveolar bone. The results in Fig. 3 show that we can deduce that drilling by the piezoelectric method is more accurate than the traditional method, as the variation in minimum and maximum ISQs was more uniform in the piezosurgery group. Clinical methods commonly used to assess implant stability and osseointegration include percussion, mobility tests, and radiographs. All these methods are limited by their lack of standardisation, poor sensitivity, and susceptibility to operator-associated variables.18–20 Recently, a modern and uninvasive diagnostic technique called resonance frequency analysis has been used for the evaluation and measurement of the stability of implants within bone. The reasons to use
this technique are that it is rapid, straightforward, and easy to accomplish as part of routine clinical procedure, and there is no risk of discomfort to the patient. ISQ indices that have been analysed showed a continued increase in stability, although it was still below that of the piezoelectric group. The success of the piezoelectric technique may be related to the accommodation of the bone after compression during installation of the implant and more favourable biological changes in early remodelling of the bone. Because this method is more delicate, it could have considerable benefits for bone healing.21 In addition, for the conventional drilling technique, the mean ISQ over the 3 time points for the conventional drilling technique followed
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a gradual increase (that was almost linear), whereas for the piezoelectric method, the mean. ISQ during the 3 time points followed a different pattern: although it was higher in the first measurement, it remained at essentially the same level during the second measurement and increased significantly only after 150 days at the time of the third measurement. After 150 days, the values of ISQ for the piezoelectric method were higher than those for the conventional drilling method. The probable explanation is that in the last period of bone remodelling the values gradually increased as the bone repaired and were favoured by factors that benefited this gradual increase.22 Some authors found that the ISQ in regular driller holes continued increasing after 12 months of immediate loading, but described little difference between 3 and 6 months.18 In the present study there was an increase in the ISQ between the periods 90 and 150 days, probably as a result of movement during manoeuvres and procedures for the preparation of rehabilitation (healing abutment, transfer, or prosthetic abutment), which generate loads of low frequency and low intensity. Preliminary data have suggested that ISQ measures of up to 60–65 at the time of insertion of the implant predict a good prognosis for immediate implant loading.23 In the present series the values were almost always higher than this, suggesting that the development of immediate loading protocols after the piezoelectric method of installation could be developed in the near future. These results are of practical importance to increase predictability in cases of immediate loading, for example. To date, millions of dental implants have been successfully placed using a conventional drilling approach; however, this technique is less suitable for high-risk patients such as those who require placement of implants in irradiated bone. The results obtained in this study show the advantages of the piezosurgical technique for osteotomies, and additional future research should be conducted in this promising area of study. It should include long-term monitoring, particularly after loading the implants, and should be designed to assess the possible similarity in ISQs between the 2 methods.
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