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Internal bone temperature change during guided surgery preparations for dental implants: an in vitro study. ARTICLE in THE INTERNATIONAL JOURNAL OF ORAL & MAXILLOFACIAL IMPLANTS · JANUARY 2013 Impact Factor: 1.49 · DOI: 10.11607/jomi.2854 · Source: PubMed
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6 AUTHORS, INCLUDING: Marco Migliorati
Alessio Signori
Università degli Studi di Genova
Università degli Studi di Genova
22 PUBLICATIONS 54 CITATIONS
85 PUBLICATIONS 184 CITATIONS
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Armando Silvestrini-Biavati
Stefano Benedicenti
Università degli Studi di Genova
Università degli Studi di Genova
55 PUBLICATIONS 62 CITATIONS
51 PUBLICATIONS 236 CITATIONS
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Available from: Armando Silvestrini-Biavati Retrieved on: 19 June 2015
Internal Bone Temperature Change During Guided Surgery Preparations for Dental Implants: An in Vitro Study Marco Migliorati1/Leonardo Amorfini2/Alessio Signori, MSc3/Fabrizio Barberis4/Armando Silvestrini Biavati5/Stefano Benedicenti, DDS6[AU: Please provide degrees for all authors] Purpose: The aim of this pig model study is to verify whether the use of devices (surgical templates) or procedures (flapless or flap) of guided surgery may cause a potentially pathologic increase of temperature during the bone preparation. Materials and Methods: In this in vitro study, pig ribs with mean cortical thickness of 1.90 mm were used. Open-flap and flapless guided surgery (experimental groups OGS and FGS) and open-flap and flapless conventional technique (control groups OSS and OFS) were performed. Temperature changes were recorded at a distance of 0.5 mm from the final test osteotomy by 2 thermocouples at depths of 1.5 (point A) and 12 mm (point B). Data were collected from 80 measurements, 10 for each group. Results: A statistically significant increase of temperature was reported for FGS and OGS groups considering the measurement at point A (mean ∆t 4.81 degrees and 4.21 degrees, respectively). The measurement at Point B for FGS group compared to the FSS group did not differ significantly for the 3-mm drill, nor did the OSS group with the 2-mm drill. [AU: Please confirm this sentence was edited correctly] Conclusions: Site preparation with surgical stents generated higher bone temperature than conventional drilling. However, this heat generation did not reach temperature levels dangerous for the bone. INT J ORAL MAXILLOFAC IMPLANTS 2013;28:XX–XX. DOI:10.11607/JOMI.2854 Key words: bone drilling, dental implants, guided surgery, heat generation, implant drills, thermocouple.
T
he overall success of dental implants largely depends on the process of osseointegration.1 Secondary stability first starts with an appropriate healing 1Dentist,
Orthognathodontic Specialist, Adjunct Professor in Orthodontics; Orthodontics Department, Genoa University School of Dentistry, Italy. 2Dentist, Private Practice, Gallarate, Italy. 3Department of Health Sciences, Section of Biostatistics, Genoa University, Italy. [AU: Please provide professional title for Dr Signori] 4 Assistant Professor, Department of Building, Chemical and Environmental Engineering, Genoa University, Italy; Assistant Professor, Research Center for Material Science and Technology. Genoa University, Italy. 5Assistant Professor, DISC, Orthodontics Department, Genoa University School of Dentistry, Italy; Assistant Professor, Research Center for Material Science and Technology. Genoa University, Italy.[AU: Please provide full name of institution abbreviated “DISC”] 6Associate Professor, Genoa University School of Dentistry, Italy; Associate Professor, DISC, Genoa University, Italy; Associate Professor, Research Center for Material Science and Technology. Genoa University, Italy. [AU: Please confirm all affiliations are listed correctly] [AU: Please provide one corresponding author name, mailing address, and email]
phase immediately after implant placement, when a complex variety of phenomena begin around the implant surface. For this reason, an excessive increase of bone temperature during implant site preparation should be avoided. Primary healing is the first process to achieve long-term success of dental implants, and both thermal and mechanical injuries in bone drilling may produce heat-induced bone tissue damage.2 In vivo studies have demonstrated the damaging effect of heat on subsequent bone healing and have determined that bone can tolerate a critical temperature threshold value of 47°C without necrotic breakdown.2–4 When bone heating is raised to 50°C, the biologic response is generally absent.5 [AU: Please clarify – there is no biologic response at 50°C, but previous sentence says 47°C is the maximum temperature before damage occurs.] For this reason, any kind of thermal and mechanical injuries to the bone should be avoided.6 Recently, computer-assisted implant surgery has been introduced,7,8: using surgical templates that could improve the precision of implant placement using a flapless procedure with or without immediate loading. In a compromised situation these tools can be effectively used for a comprehensive rehabilitation.9 So far, literature on heat changes during implant site The International Journal of Oral & Maxillofacial Implants 1
Migliorati et al
a
b
c
d
Fig 1 Bone specimen preparation. (a) Open-flap standard surgery (OSS), (b) flapless standard surgery (FSS), (c) open-flap guided surgery (OGS), and (d) flapless guided surgery (FGS).
preparation has been focused on drill material,10 drill shape,11 or intraosseous temperature modifications related to different implant preparation devices.12 To date, no data have been published on heat generation during implant site preparation with guided surgery. The aim of this research was to evaluate and to compare intraosseous thermal modifications using the following approaches: open-flap standard surgery (OSS), flapless standard surgery (FSS), open-flap guided surgery (OGS), and flapless guided surgery (FGS).
MATERIAL AND METHODS Internal bone temperature changes were analyzed in vitro using one implant drill system (Biomet 3i) in four different approaches: OSS, FSS, OGS, and FGS.
Bone Specimen Preparation
Forty fresh pig ribs were collected and were sliced into 35-mm-long specimens. Pig ribs were chosen for their great homogeneity in cortical thickness. Bone specimens were cleaned and stored in a saline solution constantly maintained at 37 ± 1°C until the moment of their use and different set-ups for each group sample were established: OSS group: Bone specimens were cleaned and used without other interventions (Fig 1a). FSS group: Specimens were covered by 2 mm of red wax (Tenatex Red, Kemdent) simulating soft tissue. Wax totally covered the apical third of the bone specimen (Fig 1b). OGS group: Bone samples were drilled directly without soft tissue simulation. A navigator master cylinder (5-mm wide and 5-mm deep) was housed in an adapted surgical guide fixed on the bone specimen (Fig 1c). 2 Volume 28, Number 5, 2013
FGS group: Bone specimens were covered by 2 mm of red wax (Tenatex Red, Kemdent) simulating soft tissue. A navigator master cylinder (5-mm wide and 5-mm deep) was housed in an adapted surgical guide fixed on the bone specimen (Fig 1d) All the master cylinders were provided with the original resin structure including their own watering holes made by the surgical stent manufacturing center (Materialise). Cortical thickness measurements to ensure homogeneity at baseline among the groups were evaluated using electronic calipers (SAMA Italia) with a precision of 0.02 mm and were successively statistically analyzed. Mean cortical thickness of 1.90 mm was found (standard deviation [SD], 0.27). Two holes were drilled for each specimen (point A and point B, 1.0-mm diameter) to house the extremity of the thermocouples. The hole at point A was drilled to 1.5 mm depth (cortical layer) and the hole at point B was prepared 12 mm below A (marrow bone layer). [AU: Please confirm sentence was edited correctly] Both A and B were drilled 1 mm from the implant drill insertion site to avoid damage to the thermocouples.12,13 An endodontic ruler was used to mark the exact depth of drilling (Fig 2).
Experimental Set-Up
The handpiece (Intrasurg 300 Plus, Kavo) was fixed to the vertical drill stand and a static load of 2.5 kg was applied. A vertical perforation stop was set at 12 mm for the OSS and FSS groups, and at 12 + 5 mm [AU: Is this correct or should it be 12 ± 5?] of depth on the vertical drill stand for the OGS and FGS groups. A surgical drilling unit (Implantmed, Biomet 3i) was used, with torque and drilling speed control. Rotational speed was set at 1,200 RPM with maximum torque set at 25 Ncm according to the recommendation of the manufacturers. Implant site preparation was performed with 2 different sets of working tips: in the OSS and FSS groups, 15-mm-long twisted drills with diameters of 2.0 and 3.0 mm (ACT Twist Drill, Biomet 3i) were used, and in the OGS and FGS groups, 20-mmlong drills with diameters of 2.0 and 3.0 mm and their respective drill handles (Navigator Twist Drill, Biomet 3i) were used. Temperature registration was performed with type K thermocouples 0.5 mm in diameter with a mineral insulation and a temperature measurement range of –50°C to 400°C (Tersid, Milano, Italy). Room temperature (22.5°C) saline solution was used for constant irrigation (50 ml per minute).
Experimental Protocol
Bone blocks were immobilized in a customized metal blocks with micrometric regulation in two axes. Each sample was drilled twice: with the 2.0-mm diameter
Migliorati et al
Fig 2 Experimental setup and thermocouple positions.
Plexiglass template
Point A
Bone marrow
Thermocouple thermometer
Point B
Cortical bone Customized metal block Computer
bur first and with the 3.0-mm diameter bur second. There were a total of 20 drilled sites per group, and 160 temperature change registrations were obtained overall. Each group used new drills. Drilling procedures started when both bone temperature analyses registered a constant value for at least 20 seconds. Both temperature variations were visualized every second on the thermocouple thermometer (Model HD2128.1, Delta Ohm) and saved on dedicated software (Delta Log 9, Delta Ohm). To avoid perforation position errors of the bur and to reduce thermocouple movement, a plexiglass template was created.
Data Collection
Drilling was controlled by two operators. Data from drilling procedures were directly and simultaneously uploaded to the software for thermocouple A and B. Initial bone temperatures, as well as temperature variations, were recorded for each specimen. A table with cortical and cancellous temperature variations was created and blinded with regard to the group and drilling depth.
Statistical Analysis
An expert operator received blinded data and conducted the statistical analysis. A nonparametric Kruskal-Wallis test was used to evaluate the differences of cortical thickness among the groups at the baseline. Median and interquartile range) were shown for outcome differences of temperature. Cubic root transformation or log transformation was applied to outcomes due to asymmetric distribution. One-way analysis of variance (ANOVA) was performed to evaluate the differences in temperature among systems in general and after stratifying for drills and points of measurement. This was followed by Bonferroni post-hoc test if homogeneity of variances
was not rejected or Tamhane post-hoc test for inequality of variances between groups. Three-way ANOVA was used to evaluate the differences in temperature among systems considering milling cutters and points of measurement as factors and including the interaction between factors. Levene’s test was used to evaluate homogeneity of variances between groups. A P value of .05 was considered statistically significant. SPSS (IBM) was used for computation.
RESULTS For cortical thickness, no differences were observed among the groups (P = .99). Table 1a shows the temperature difference in each system and Table 1b reports the post-hoc comparisons among systems obtained using the Bonferroni test. The maximum increase in temperature was found in the OGS group (median, 2.55°C) but no significant difference between the OGS and FGS groups (median, 2.50°C) was detected. Significant differences were found comparing the OGS with both the FSS and OSS groups, and comparing the FGS group with both FSS and OSS groups (P < .001). Significant differences [AU: correct?] in temperature change were found between points of measurement (P < .001), with a greater increase of temperature at point A, and between drill diameters (P = .049) with greater outcome values found for 2-mm diameter drills. Differences in temperature were simultaneously associated with groups and point of measurement (P for interaction = .05). Similarly significant interactions of surgical procedure, depth of drilling, and effect of drill type on temperature difference (P for interaction < .001) were observed, whereas no statistically significant interacThe International Journal of Oral & Maxillofacial Implants 3
Migliorati et al
Table 1a
Temperature Difference (°C) Among Groups Temperature Difference Median (IQR)
Group OGS
2.55 (1.15 – 4.30)
FGS
2.50 (1.02 – 4.68)
FSS
0.70 (0.25 – 1.48)
OSS
0.82 (0.40 – 1.63)
IQR = interquartile range.
Table 1b
Post-Hoc Comparisons Between Groups (P values)
OGS–FGS
OGS–FSS
OGS–OSS
FGS–FSS
FGS–OSS
FSS–OSS
< .999
< .001
< .001
< .001
Internal bone temperature change during guided surgery preparations for dental implants: an in vitro study. ARTICLE in THE INTERNATIONAL JOURNAL OF ORAL & MAXILLOFACIAL IMPLANTS · JANUARY 2013 Impact Factor: 1.49 · DOI: 10.11607/jomi.2854 · Source: PubMed
DOWNLOADS
VIEWS
63
57
6 AUTHORS, INCLUDING: Marco Migliorati
Alessio Signori
Università degli Studi di Genova
Università degli Studi di Genova
22 PUBLICATIONS 54 CITATIONS
85 PUBLICATIONS 184 CITATIONS
SEE PROFILE
SEE PROFILE
Armando Silvestrini-Biavati
Stefano Benedicenti
Università degli Studi di Genova
Università degli Studi di Genova
55 PUBLICATIONS 62 CITATIONS
51 PUBLICATIONS 236 CITATIONS
SEE PROFILE
SEE PROFILE
Available from: Armando Silvestrini-Biavati Retrieved on: 19 June 2015
Internal Bone Temperature Change During Guided Surgery Preparations for Dental Implants: An in Vitro Study Marco Migliorati1/Leonardo Amorfini2/Alessio Signori, MSc3/Fabrizio Barberis4/Armando Silvestrini Biavati5/Stefano Benedicenti, DDS6[AU: Please provide degrees for all authors] Purpose: The aim of this pig model study is to verify whether the use of devices (surgical templates) or procedures (flapless or flap) of guided surgery may cause a potentially pathologic increase of temperature during the bone preparation. Materials and Methods: In this in vitro study, pig ribs with mean cortical thickness of 1.90 mm were used. Open-flap and flapless guided surgery (experimental groups OGS and FGS) and open-flap and flapless conventional technique (control groups OSS and OFS) were performed. Temperature changes were recorded at a distance of 0.5 mm from the final test osteotomy by 2 thermocouples at depths of 1.5 (point A) and 12 mm (point B). Data were collected from 80 measurements, 10 for each group. Results: A statistically significant increase of temperature was reported for FGS and OGS groups considering the measurement at point A (mean ∆t 4.81 degrees and 4.21 degrees, respectively). The measurement at Point B for FGS group compared to the FSS group did not differ significantly for the 3-mm drill, nor did the OSS group with the 2-mm drill. [AU: Please confirm this sentence was edited correctly] Conclusions: Site preparation with surgical stents generated higher bone temperature than conventional drilling. However, this heat generation did not reach temperature levels dangerous for the bone. INT J ORAL MAXILLOFAC IMPLANTS 2013;28:XX–XX. DOI:10.11607/JOMI.2854 Key words: bone drilling, dental implants, guided surgery, heat generation, implant drills, thermocouple.
T
he overall success of dental implants largely depends on the process of osseointegration.1 Secondary stability first starts with an appropriate healing 1Dentist,
Orthognathodontic Specialist, Adjunct Professor in Orthodontics; Orthodontics Department, Genoa University School of Dentistry, Italy. 2Dentist, Private Practice, Gallarate, Italy. 3Department of Health Sciences, Section of Biostatistics, Genoa University, Italy. [AU: Please provide professional title for Dr Signori] 4 Assistant Professor, Department of Building, Chemical and Environmental Engineering, Genoa University, Italy; Assistant Professor, Research Center for Material Science and Technology. Genoa University, Italy. 5Assistant Professor, DISC, Orthodontics Department, Genoa University School of Dentistry, Italy; Assistant Professor, Research Center for Material Science and Technology. Genoa University, Italy.[AU: Please provide full name of institution abbreviated “DISC”] 6Associate Professor, Genoa University School of Dentistry, Italy; Associate Professor, DISC, Genoa University, Italy; Associate Professor, Research Center for Material Science and Technology. Genoa University, Italy. [AU: Please confirm all affiliations are listed correctly] [AU: Please provide one corresponding author name, mailing address, and email]
phase immediately after implant placement, when a complex variety of phenomena begin around the implant surface. For this reason, an excessive increase of bone temperature during implant site preparation should be avoided. Primary healing is the first process to achieve long-term success of dental implants, and both thermal and mechanical injuries in bone drilling may produce heat-induced bone tissue damage.2 In vivo studies have demonstrated the damaging effect of heat on subsequent bone healing and have determined that bone can tolerate a critical temperature threshold value of 47°C without necrotic breakdown.2–4 When bone heating is raised to 50°C, the biologic response is generally absent.5 [AU: Please clarify – there is no biologic response at 50°C, but previous sentence says 47°C is the maximum temperature before damage occurs.] For this reason, any kind of thermal and mechanical injuries to the bone should be avoided.6 Recently, computer-assisted implant surgery has been introduced,7,8: using surgical templates that could improve the precision of implant placement using a flapless procedure with or without immediate loading. In a compromised situation these tools can be effectively used for a comprehensive rehabilitation.9 So far, literature on heat changes during implant site The International Journal of Oral & Maxillofacial Implants 1
Migliorati et al
a
b
c
d
Fig 1 Bone specimen preparation. (a) Open-flap standard surgery (OSS), (b) flapless standard surgery (FSS), (c) open-flap guided surgery (OGS), and (d) flapless guided surgery (FGS).
preparation has been focused on drill material,10 drill shape,11 or intraosseous temperature modifications related to different implant preparation devices.12 To date, no data have been published on heat generation during implant site preparation with guided surgery. The aim of this research was to evaluate and to compare intraosseous thermal modifications using the following approaches: open-flap standard surgery (OSS), flapless standard surgery (FSS), open-flap guided surgery (OGS), and flapless guided surgery (FGS).
MATERIAL AND METHODS Internal bone temperature changes were analyzed in vitro using one implant drill system (Biomet 3i) in four different approaches: OSS, FSS, OGS, and FGS.
Bone Specimen Preparation
Forty fresh pig ribs were collected and were sliced into 35-mm-long specimens. Pig ribs were chosen for their great homogeneity in cortical thickness. Bone specimens were cleaned and stored in a saline solution constantly maintained at 37 ± 1°C until the moment of their use and different set-ups for each group sample were established: OSS group: Bone specimens were cleaned and used without other interventions (Fig 1a). FSS group: Specimens were covered by 2 mm of red wax (Tenatex Red, Kemdent) simulating soft tissue. Wax totally covered the apical third of the bone specimen (Fig 1b). OGS group: Bone samples were drilled directly without soft tissue simulation. A navigator master cylinder (5-mm wide and 5-mm deep) was housed in an adapted surgical guide fixed on the bone specimen (Fig 1c). 2 Volume 28, Number 5, 2013
FGS group: Bone specimens were covered by 2 mm of red wax (Tenatex Red, Kemdent) simulating soft tissue. A navigator master cylinder (5-mm wide and 5-mm deep) was housed in an adapted surgical guide fixed on the bone specimen (Fig 1d) All the master cylinders were provided with the original resin structure including their own watering holes made by the surgical stent manufacturing center (Materialise). Cortical thickness measurements to ensure homogeneity at baseline among the groups were evaluated using electronic calipers (SAMA Italia) with a precision of 0.02 mm and were successively statistically analyzed. Mean cortical thickness of 1.90 mm was found (standard deviation [SD], 0.27). Two holes were drilled for each specimen (point A and point B, 1.0-mm diameter) to house the extremity of the thermocouples. The hole at point A was drilled to 1.5 mm depth (cortical layer) and the hole at point B was prepared 12 mm below A (marrow bone layer). [AU: Please confirm sentence was edited correctly] Both A and B were drilled 1 mm from the implant drill insertion site to avoid damage to the thermocouples.12,13 An endodontic ruler was used to mark the exact depth of drilling (Fig 2).
Experimental Set-Up
The handpiece (Intrasurg 300 Plus, Kavo) was fixed to the vertical drill stand and a static load of 2.5 kg was applied. A vertical perforation stop was set at 12 mm for the OSS and FSS groups, and at 12 + 5 mm [AU: Is this correct or should it be 12 ± 5?] of depth on the vertical drill stand for the OGS and FGS groups. A surgical drilling unit (Implantmed, Biomet 3i) was used, with torque and drilling speed control. Rotational speed was set at 1,200 RPM with maximum torque set at 25 Ncm according to the recommendation of the manufacturers. Implant site preparation was performed with 2 different sets of working tips: in the OSS and FSS groups, 15-mm-long twisted drills with diameters of 2.0 and 3.0 mm (ACT Twist Drill, Biomet 3i) were used, and in the OGS and FGS groups, 20-mmlong drills with diameters of 2.0 and 3.0 mm and their respective drill handles (Navigator Twist Drill, Biomet 3i) were used. Temperature registration was performed with type K thermocouples 0.5 mm in diameter with a mineral insulation and a temperature measurement range of –50°C to 400°C (Tersid, Milano, Italy). Room temperature (22.5°C) saline solution was used for constant irrigation (50 ml per minute).
Experimental Protocol
Bone blocks were immobilized in a customized metal blocks with micrometric regulation in two axes. Each sample was drilled twice: with the 2.0-mm diameter
Migliorati et al
Fig 2 Experimental setup and thermocouple positions.
Plexiglass template
Point A
Bone marrow
Thermocouple thermometer
Point B
Cortical bone Customized metal block Computer
bur first and with the 3.0-mm diameter bur second. There were a total of 20 drilled sites per group, and 160 temperature change registrations were obtained overall. Each group used new drills. Drilling procedures started when both bone temperature analyses registered a constant value for at least 20 seconds. Both temperature variations were visualized every second on the thermocouple thermometer (Model HD2128.1, Delta Ohm) and saved on dedicated software (Delta Log 9, Delta Ohm). To avoid perforation position errors of the bur and to reduce thermocouple movement, a plexiglass template was created.
Data Collection
Drilling was controlled by two operators. Data from drilling procedures were directly and simultaneously uploaded to the software for thermocouple A and B. Initial bone temperatures, as well as temperature variations, were recorded for each specimen. A table with cortical and cancellous temperature variations was created and blinded with regard to the group and drilling depth.
Statistical Analysis
An expert operator received blinded data and conducted the statistical analysis. A nonparametric Kruskal-Wallis test was used to evaluate the differences of cortical thickness among the groups at the baseline. Median and interquartile range) were shown for outcome differences of temperature. Cubic root transformation or log transformation was applied to outcomes due to asymmetric distribution. One-way analysis of variance (ANOVA) was performed to evaluate the differences in temperature among systems in general and after stratifying for drills and points of measurement. This was followed by Bonferroni post-hoc test if homogeneity of variances
was not rejected or Tamhane post-hoc test for inequality of variances between groups. Three-way ANOVA was used to evaluate the differences in temperature among systems considering milling cutters and points of measurement as factors and including the interaction between factors. Levene’s test was used to evaluate homogeneity of variances between groups. A P value of .05 was considered statistically significant. SPSS (IBM) was used for computation.
RESULTS For cortical thickness, no differences were observed among the groups (P = .99). Table 1a shows the temperature difference in each system and Table 1b reports the post-hoc comparisons among systems obtained using the Bonferroni test. The maximum increase in temperature was found in the OGS group (median, 2.55°C) but no significant difference between the OGS and FGS groups (median, 2.50°C) was detected. Significant differences were found comparing the OGS with both the FSS and OSS groups, and comparing the FGS group with both FSS and OSS groups (P < .001). Significant differences [AU: correct?] in temperature change were found between points of measurement (P < .001), with a greater increase of temperature at point A, and between drill diameters (P = .049) with greater outcome values found for 2-mm diameter drills. Differences in temperature were simultaneously associated with groups and point of measurement (P for interaction = .05). Similarly significant interactions of surgical procedure, depth of drilling, and effect of drill type on temperature difference (P for interaction < .001) were observed, whereas no statistically significant interacThe International Journal of Oral & Maxillofacial Implants 3
Migliorati et al
Table 1a
Temperature Difference (°C) Among Groups Temperature Difference Median (IQR)
Group OGS
2.55 (1.15 – 4.30)
FGS
2.50 (1.02 – 4.68)
FSS
0.70 (0.25 – 1.48)
OSS
0.82 (0.40 – 1.63)
IQR = interquartile range.
Table 1b
Post-Hoc Comparisons Between Groups (P values)
OGS–FGS
OGS–FSS
OGS–OSS
FGS–FSS
FGS–OSS
FSS–OSS
< .999
< .001
< .001
< .001
