Research Article Temperature Changes of Pulp …downloads.hindawi.com/journals/tswj/2014/589461.pdfResearch Article Temperature Changes of Pulp Chamber during In Vitro Laser Welding

Research ArticleTemperature Changes of Pulp Chamber during In VitroLaser Welding of Orthodontic Attachments

Eren EGman1 RJdvan OkGayan1 Oral Soumlkuumlcuuml1 and Serdar UumlGuumlmez2

1 Department of Orthodontics Faculty of Dentistry Gaziantep University 27310 Gaziantep Turkey2Department of Orthodontics Faculty of Dentistry Bezmialem Vakif University 34093 Istanbul Turkey

Correspondence should be addressed to Rıdvan Oksayan ridvanoksayanhotmailcom

Received 31 August 2013 Accepted 24 October 2013 Published 14 January 2014

Academic Editors T Morotomi and K H Zawawi

Copyright copy 2014 Eren Isman et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The use of lasers has been suggested for orthodontists to fabricate or repair orthodontic appliances by welding metals directly inthe mouth This work aimed to evaluate the temperature changes in the pulp chamber during welding of an orthodontic wire toan orthodontic molar band using Nd YAG laser in vitro A freshly extracted human third molar with eliminated pulpal tissueswas used J-type thermocouple wire was positioned in the pulp chamber A conductor gel was used in the transferring of outsidetemperature changes to the thermocouple wire An orthodontic band was applied to the molar tooth and bonded using light curedorthodontic cement Twenty five mm length of 06mm diameter orthodontic stainless steel wires was welded to the orthodonticband using Nd YAG laser operated at 94 watt Temperature variation was determined as the change from baseline temperatureto the highest temperature was recorded during welding The recorded temperature changes were between 18 and 68∘C (mean33plusmn 11∘C) The reported critical 55∘C level was exceeded in only one sample The results of this study suggest that intraoral use oflasers holds great potential for the future of orthodontics and does not present a thermal risk Further studies with larger samplesand structural analysis are required

1 Introduction

Numerous studies have been conducted on the use of laserbeams for welding dental metals especially titanium alloys[1ndash4] Following Maimanrsquos introduction of the first appli-ance in 1960 many fields have focused on this technologyincluding industry the military communications and gen-eraldental medicine [5] Because of their effects on reducingthe heat affected zone (HAZ) around the welding spot andtheir ability to maintain material properties Nd YAG lasershave beenused inmetalwelding from the beginningAnotheradvantage of this laser is that it can join differentmetalsmuchmore successfully than other common techniques can [6]

Laser welding techniques began being used in dentaloffices and laboratories after 1970 [7] Today with the helpof laser welding a wide variety of procedures may beperformed For example dental prostheses and bridges canbe constructed or fixed [8 9] implant titanium milled fixeddentures can be repaired [10] and custom-made laser-weldedtitanium implant prosthetic abutments can be generated [11]

Additionally immediate replacement of removable partialdentures can be performed [12] orthodontic space maintain-ers can be fabricated [13] orthodontic wires can be joined[14] and broken appliances can be fixed [2]

Laser-welding techniques are being used intraorally withan optical fiber transmission These techniques have beenused in many dental offices for various procedures in recentyears In this way clinicians using this technique can carryout an immediate repair of metallic fixed removable andorthodontic broken prostheses and appliances in their ownoffices thus reducing the time needed for such repairs [2 15]One of the side effects of the welding procedure howeveris the heat produced during the procedure This heat maycause thermal damage of the periodontal tissues and the toothpulp Fornaini et al tested the thermal changes surroundingthe teeth using two hemispherical metal plates placed on tomandibular molars which were laser welded at three pointsThe temperature changes in the pulp chamber sulcus rootand alveolar bone were measured with four K-thermocouplesystems [16] The authors reported that the highest thermal

Hindawi Publishing Corporatione Scientific World JournalVolume 2014 Article ID 589461 5 pageshttpdxdoiorg1011552014589461

2 The Scientific World Journal

(a) (b)

Figure 1 (a)The top view of the acrylic platform and themolar toothwith orthodontic band placed in themiddle (b)The bottom image of theacrylic platform Note that the inside of the platformwas emptied and the crown of the molar tooth was inserted on top of itThe root portionwas removed and the cap of the pulp can be seen with conductor gel injected into the cavity providing the transfer of outside temperaturechanges to the thermocouple wire imitating the pulpal tissue conductibility The cable was inserted through a hole on the platform

increase was 15∘C in the pulp chamber 07∘C in the sulcus03∘C in the root and 03∘C in the alveolar bone This studydemonstrated the biological compatibility of the intraorallaser welding method with the surrounding hard and softtissues as the parameters used in this work [16]

Bock et al [13] demonstrated the laser-welding procedureof orthodontic stainless steel wire to orthodontic molarbands for constructing space maintainers Fornaini declaredthat the fabrication of space maintainers can be carried outintraorally He also tested the pulpal and surrounding tissue-related temperature changes during laser welding of metalplates on calf teeth and found no critical pulpal temperaturechange However orthodontic molar bands covered andsurrounded the molar tooth and thus we hypothesized thatthe temperature changes during laser welding may be higherthan those observed with FornainirsquosmethodMoreover usingextracted human teeth may affect the outcome of the experi-ment since bovine teeth anatomy and structure may not berepresentative of the thermal conductivity of human teethwhich have been used in many studies [17ndash23] Thereforethe aim of this study was to evaluate the temperature changesin the pulp chamber during welding of an orthodontic wireto an orthodontic molar band using an Nd YAG laser invitro For the purposes of this study the null hypothesisassumed that laserwelding of orthodonticwire does not causetemperature increases above the critical threshold value of55∘C as reported by Zach and Cohen [24]

2 Materials and Methods

A freshly extracted human third molar tooth was used inthis study The total thickness of the tooth including dentineand enamel at the level of the crown was 172mm on themesial side 186mmon the distal side 170mmon the lingualside and 233mm on the buccal side The root was separatedfrom the crown and the intrapulpal tissues were eliminatedAn acrylic platform was constructed and emptied insideThetooth was inserted on top of this platform (Figures 1(a) and1(b)) In the middle of the platform a hole was drilled and aJ-type thermocouple wire with a 036 inch diameter (Omega

Engineering Stamford CT USA) was pushed through thehole and positioned in the center of the pulp chamberThere were two wires in the thermocouple cable and oneof them was placed in the medial fissure of the pulp roofand the other was located in the distal fissure (Figure 2)A conductor gel (Manhattan Computer Products China)that imitated the pulpal tissue conductibility was injectedinto the pulp to ensure transfer of pulpal wall temperaturechanges to the thermocouple wire An orthodontic molarband (3M Unitek Monrovia CA USA) was applied to themolar tooth and bonded using multicure glass ionomerorthodontic band cement (3M Unitek Monrovia CA USA)The film thickness of the glass ionomer cement between thecrown and orthodontic band was approximately 25ndash35 120583m inaccordance with the literature [25] The space in the acrylicplatform was then filled with C-silicone impression material(Zhermack Zetaplus Rovigo Italy) to fix the cable in itsposition After this both lateral and occlusal radiograms(VarioDG Sirona BensheimGermany)were taken to ensurethat the wire was properly stabilized in its place (Figure 2)

Twenty pieces of 06mm diameter orthodontic stainlesssteel wire (Levanit Lewadental RemchingenGermany)werecut at 5 cm lengths and welded to the orthodontic bandusing the Nd YAG laser (Fidelis Plus III Fotona LjubljanaSlovenia) The study design is shown in Figure 3(a)

The Nd YAG laser parameters were as follows outputpower 940W frequency 1 Hz pulse duration 15ms work-ing distance 31mm spot diameter 06mm energy 940 Jfluency 2300 Jcm2 (Figure 4) To standardize the workingdistance an accessorial stick measuring 31mm in length wasattached to the laser probe (Figure 3(b)) The metal wirewelded to the molar band is shown in Figure 3(c) A smallpilot study demonstrated that three pulses are enough tosecurely weld the piece of wire and for standardizationthe welding process was performed with only three pulsesthroughout the study Compressed air was used after eachshut to restore the test sample to initial room temperature forstandardization

The J-type thermocouple wire was connected to a datalogger (XR440 Pocket Logger Pace Scientific NC USA)

The Scientific World Journal 3

(a) (b)

Figure 2 Lateral and occlusal radiogramswere taken to ensure that the wire was properly inserted in its place Twowires in the thermocouplecable can be seen one of them was placed in the medial fissure of the pulp cap and the other was located in distal fissure

(a) (b) (c)

Figure 3 (a) The study design of the recent study A thermocouple device on the right the banded tooth with an acrylic platform in themiddle and the laser welding probe (b) Fiber-delivered probe Nd YAG laser on which 31mm stick was attached for standardization (c)Thewelded stainless steel 001610158401015840 orthodontic wire to the molar band

During the welding procedures temperature variations weredetermined and the changes from the baseline room tem-perature (26∘C) to the highest temperatures were recordedThe sampling rate of the data logger was two seconds Thecollected data were monitored in real time and transferredto a computer The data was available in both tabular andgraphic form Temperature changes were recorded everytwo seconds from the start of welding and continued forapproximately 10ndash20 seconds until the temperature started todecrease The outcome data (Figure 4) were analyzed usingdescriptive statistics including mean maximum minimumand standard deviation

3 Results and Discussion

The outcome was established with a time-temperature changegraph developed by the computer software and a represen-tative graph is shown in Figure 4 In this graph the initialtemperature of the thermocouple was 26∘C and after theapplication of welding the temperature rapidly increased toa maximum value of 3280∘C These results were recordedthe alterations were calculated and statistical analyses were

33

32

31

30

29

28

27

26

202 203 204

Thermocouple

20 OL UM MESIALPL1C

(∘C)

Tue 7 Sep 2010

Figure 4 The monitor view of the computer program showing oneof the outcomes of the temperature changes during laser welding

carried outMeanmaximumminimum and standard devia-tion of the temperature change values are presented inTable 1

The statistical analyses showed that the temperature chan-ges were between 180∘C and 680∘C (mean 333 plusmn 110∘C)


Table 1 Descriptive statistics of the outcomes of thermocouple test

Temperature change (∘C)Mean 333Max 680Min 180sd 110

According to Zach and Cohenrsquos study the reported critical55∘C level [24] was exceeded in only one sample in our study(680∘C) The rest of the values were below 480∘C (mostlybetween 223∘C and 443∘C) The null hypothesis was thusaccepted

This work demonstrated the temperature changes occur-ring in the tooth pulp during laser welding of an orthodonticwire to an orthodontic molar bandThis procedure simulatesthe construction of a banded orthodontic space maintainerin the dental office

Space maintainers are fixed or removable appliances usedto preserve arch length following the premature loss orelective extraction of a tooth or teeth Fixed appliances areeasier tomaintain and they are less likely to be damaged lostor removed [26] Traditionally the band-loop fixed retainerswere generated by adapting a molar band to the related toothand having a cast model of the patient The band is thentransferred to the cast a stainless steel orthodontic roundwire is organized and bent to maintain the space next tothe adjacent tooth and then the metal is attached either bysoldering or brazingThis process needs time for constructionof the appliance in the laboratory However the intraoral laserwelding method introduced by Fornaini et al [2] is morepractical and easy to perform Moreover it is a time saver fora dental practice

A study by Nayak et al demonstrated a method thatexcluded the impression taking and casting model phase ofthe band loop space maintainer [27] However his methodstill included the first welding and initial attachment of theband andwire followed by soldering them together firmly andcementing them This is more practical than the traditionalmethod but a certain amount of chair-side time is still needed

The current study describes the temperature changes ofthe pulp cavity during the laser welding of an orthodonticband with an orthodontic stainless steel wire A similarstudy was performed by Fornaini et al [16] using a calfmandible and they showed that the temperature increases inall elements were below the safety level for pulp injury Ourfindings are in accordance with Fornainirsquos study

There are several advantages of using laser welding tech-nology in dental practicesThe use of the same parent metalseither with or without soldering reduces galvanic corrosion[28] The small diameter of the HAZ facilitates welding in avery narrow area that may be close to acrylic resin or ceramicparts without damaging the prosthetic structures [29] Italso remarkably reduces chair time or laboratory time thus

expediting the doctors and technicians [15] However someprecautions must be taken during the welding procedure Itis thought that the probe of the device should be stabilizedduring laser exposure either by fixing the holding hand to thepatientrsquos chin or by supporting it with the opposing hand

The laser device that was used in this study is capa-ble of combining two different wavelengths which areerbium yttrium-aluminum-garnet (Er YAG 2940 nm) andNd YAG (1064 nm) Due to insufficient output power forwelding metals diode lasers were left out It should also benoted that laser welding of titanium using an Nd YAG laserrequires very high pulse energies and an atmosphere of argongas Therefore there are currently limitations to using thistechnique for welding titanium intraorally

Fornaini declared that the low temperature rise in thetooth pulp during welding could be explained with the lownumber of pulses (4 to 5) and the low fluence transferred tothe biological structures (fluence = joules per square centime-ter joules = watts per second) [16] In this study the fluencewas decreased to 2300 Jcm2 compared with Fornainirsquos flu-ence parameter of 3480 Jcm2 However the mean tempera-ture rise of this study (333 plusmn 11∘C) was higher than Fornainirsquos(071 plusmn 045∘C) This might be due to the orthodontic bandwhich tightly covers the crown of the tooth and the closerapproximation of the welding spot to the pulp compared toFornainirsquos study design Moreover our study was conductedusing an extracted human tooth instead of bovine or calf teethwhich are thought to have thicker dentine and enamel layers

In this study the pulpal temperature changes were belowthe critical value of 55∘C However one of the samplesshowed a higher change which may be hazardous for pulpalhealth It can be assumed that this hazardous change oftemperature could be due to malpractice of the clinician whoaimed the laser probe directly on the molar band instead ofthe stainless steel wire Using the laser in this manner maylead to the creation of a hole on the band and cause unwantedincreases in pulpal temperature As mentioned above weld-ing applications require the clinician to be extremely attentivewhile sending the laser beam to the metals intraorally Thismay be a disadvantage of the application However intraorallaser welding is a very convenient and practical method withall its positive features Further studies with larger samplesand structural analysis are required to settle this proceduredown to a large range of dental branches

4 Conclusion

The results of this study suggest that intraoral use of lasersholds great potential for the future of orthodontics and doesnot present a thermal risk However delicate manipulationof the device is advised to minimize discomfort or possibleinjury to the surrounding tissues in case of extended expo-sure

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper


Acknowledgments

The authors would like to thank Professor Dr AslıhanUsumez for sharing her valuable expertise and the authorsalso appreciate contribution of Fotona Company (LjubljanaSlovenia) for providing special hand pieces for the study

References

[1] G Sjogren M Andersson and M Bergman ldquoLaser welding oftitanium in dentistryrdquo Acta Odontologica Scandinavica vol 46no 4 pp 247ndash253 1988

[2] C Fornaini C Bertrand M Bonanini J-P Rocca and SNammour ldquoWelding in the dental office by fiber-delivered lasera new techniquerdquo Photomedicine and Laser Surgery vol 27 no3 pp 417ndash423 2009

[3] C Bertrand Y le Petitcorps L Albingre and V DupuisldquoOptimization of operator and physical parameters for laserwelding of dental materialsrdquo British Dental Journal vol 196 no7 pp 413ndash418 2004

[4] H Apotheker I Nishimura and C Seerattan ldquoLaser-welded vssoldered nonprecious alloy dental bridges a comparative studyrdquoLasers in Surgery and Medicine vol 4 no 2 pp 207ndash213 1984

[5] M Bertolotti The History of the Laser Taylor and FrancisLondon UK 1999

[6] H B Cary Ed Modern Welding Technology Prentice HallColumbus Ohio USA 2002

[7] T E Gordon and D L Smith ldquoA laser in dental labrdquo in LaserFocus Magazine 1970

[8] R Schneider ldquoFull mouth restoration on dental implantsutilizing titanium laser-welded frameworksrdquo Journal of Estheticand Restorative Dentistry vol 21 no 4 pp 215ndash226 2009

[9] C Fornaini F Passaretti E Villa et al ldquoIntraoral laser weldingultrastructural and mechanical analysis to compare laboratorylaser and dental laserrdquo Lasers in Medical Science vol 26 no 4pp 415ndash420 2011

[10] S Prasad and E A Monaco Jr ldquoRepairing an implant titaniummilled framework using laser welding technology a clinicalreportrdquo Journal of Prosthetic Dentistry vol 101 no 4 pp 221ndash225 2009

[11] M A Iglesia-Puig ldquoCustom-made laser-welded titaniumimplant prosthetic abutmentrdquo Journal of Prosthetic Dentistryvol 94 no 4 pp 401ndash403 2005

[12] L Hassan A S Juszczyk and R K F Clark ldquoImmediatereplacement removable partial dentures with cobalt-chromiumframeworks rationale technology and a case reportrdquo Journal ofOral Rehabilitation vol 32 no 10 pp 772ndash775 2005

[13] J J Bock J Bailly C R Gernhardt and R A W FuhrmannldquoFracture strength of different soldered andwelded orthodonticjoining configurations with and without filling materialrdquo Jour-nal of Applied Oral Science vol 16 no 5 pp 328ndash335 2008

[14] E Watanabe G Stigall W Elshahawy and I WatanabeldquoDeflection load characteristics of laser-welded orthodonticwiresrdquo Angle Orthodontist vol 1 pp 698ndash702 2011

[15] C Fornaini P Vescovi E Merigo et al ldquoIntraoral metal laserwelding a case reportrdquo Lasers in Medical Science vol 25 no 2pp 303ndash307 2010

[16] C Fornaini C Bertrand J P Rocca et al ldquoIntra-oral laserwelding an in vitro evaluation of thermal increaserdquo Lasers inMedical Science vol 25 no 4 pp 473ndash477 2010

[17] S Malkoc T Uysal S Usumez E Isman and A BaysalldquoIn-vitro assessment of temperature rise in the pulp duringorthodontic bondingrdquo American Journal of Orthodontics andDentofacial Orthopedics vol 137 no 3 pp 379ndash383 2010

[18] A Baysal T Uysal and S Usumez ldquoTemperature rise in thepulp chamber during different stripping procedures an in vitrostudyrdquo Angle Orthodontist vol 77 no 3 pp 478ndash482 2007

[19] I Yondem S H Altintas and A Usumez ldquoTemperature riseduring resin composite Polymerization under different ceramicrestorationsrdquo European Journal of Dentistry vol 5 no 3 pp305ndash309 2011

[20] G Tosun A Usumez I Yondem and Y Sener ldquoTemperaturerise under normal and caries-affected primary tooth dentindisks during polymerization of adhesives and resin-containingdental materialsrdquo Dental Materials Journal vol 27 no 3 pp466ndash470 2008

[21] S H Altintas I YondemO Tak andA Usumez ldquoTemperaturerise during polymerization of three different provisionalmateri-alsrdquoClinical Oral Investigations vol 12 no 3 pp 283ndash286 2008

[22] A U Eldeniz A Usumez S Usumez and N Ozturk ldquoPulpaltemperature rise during light-activated bleachingrdquo Journal ofBiomedical Materials Research B vol 72 no 2 pp 254ndash2592005

[23] B Ozturk A N Ozturk A Usumez S Usumez and FOzer ldquoTemperature rise during adhesive and resin compositepolymerization with various light curing sourcesrdquo OperativeDentistry vol 29 no 3 pp 325ndash332 2004

[24] L Zach and G Cohen ldquoPulp response to externally appliedheatrdquo Oral Surgery Oral Medicine Oral Pathology vol 19 no4 pp 515ndash530 1965

[25] G Singh Textbook of Orthodontics Jaypee Brothers MedicalPublishers New Delhi India 2nd edition 2007

[26] E Laing P Ashley F B Naini and D S Gill ldquoSpace mainte-nancerdquo International Journal of Paediatric Dentistry vol 19 no3 pp 155ndash162 2009

[27] U A Nayak J Loius R Sajeev and J Peter ldquoBand and loopspace maintainer made easyrdquo Journal of the Indian Society ofPedodontics and Preventive Dentistry vol 22 no 3 pp 134ndash1362004

[28] R Zupancic A Legat and N Funduk ldquoTensile strengthand corrosion resistance of brazed and laser-welded cobalt-chromium alloy jointsrdquo Journal of Prosthetic Dentistry vol 96no 4 pp 273ndash282 2006

[29] J Tambasco T Anthony and O Sandven ldquoLaser welding in thedental laboratory an alternative to solderingrdquo Journal of DentalTechnology vol 13 no 4 pp 23ndash31 1996

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Oral OncologyJournal of

DentistryInternational Journal of



International Journal of

Biomaterials


BioMed Research International


Case Reports in Dentistry


Oral ImplantsJournal of


Anesthesiology Research and Practice


Radiology Research and Practice

Environmental and Public Health

Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


Dental SurgeryJournal of

Drug DeliveryJournal of



Oral DiseasesJournal of


Computational and Mathematical Methods in Medicine

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

PainResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Preventive MedicineAdvances in


EndocrinologyInternational Journal of



OrthopedicsAdvances in


(a) (b)

Figure 1 (a)The top view of the acrylic platform and themolar toothwith orthodontic band placed in themiddle (b)The bottom image of theacrylic platform Note that the inside of the platformwas emptied and the crown of the molar tooth was inserted on top of itThe root portionwas removed and the cap of the pulp can be seen with conductor gel injected into the cavity providing the transfer of outside temperaturechanges to the thermocouple wire imitating the pulpal tissue conductibility The cable was inserted through a hole on the platform

increase was 15∘C in the pulp chamber 07∘C in the sulcus03∘C in the root and 03∘C in the alveolar bone This studydemonstrated the biological compatibility of the intraorallaser welding method with the surrounding hard and softtissues as the parameters used in this work [16]

Bock et al [13] demonstrated the laser-welding procedureof orthodontic stainless steel wire to orthodontic molarbands for constructing space maintainers Fornaini declaredthat the fabrication of space maintainers can be carried outintraorally He also tested the pulpal and surrounding tissue-related temperature changes during laser welding of metalplates on calf teeth and found no critical pulpal temperaturechange However orthodontic molar bands covered andsurrounded the molar tooth and thus we hypothesized thatthe temperature changes during laser welding may be higherthan those observed with FornainirsquosmethodMoreover usingextracted human teeth may affect the outcome of the experi-ment since bovine teeth anatomy and structure may not berepresentative of the thermal conductivity of human teethwhich have been used in many studies [17ndash23] Thereforethe aim of this study was to evaluate the temperature changesin the pulp chamber during welding of an orthodontic wireto an orthodontic molar band using an Nd YAG laser invitro For the purposes of this study the null hypothesisassumed that laserwelding of orthodonticwire does not causetemperature increases above the critical threshold value of55∘C as reported by Zach and Cohen [24]

2 Materials and Methods

A freshly extracted human third molar tooth was used inthis study The total thickness of the tooth including dentineand enamel at the level of the crown was 172mm on themesial side 186mmon the distal side 170mmon the lingualside and 233mm on the buccal side The root was separatedfrom the crown and the intrapulpal tissues were eliminatedAn acrylic platform was constructed and emptied insideThetooth was inserted on top of this platform (Figures 1(a) and1(b)) In the middle of the platform a hole was drilled and aJ-type thermocouple wire with a 036 inch diameter (Omega

Engineering Stamford CT USA) was pushed through thehole and positioned in the center of the pulp chamberThere were two wires in the thermocouple cable and oneof them was placed in the medial fissure of the pulp roofand the other was located in the distal fissure (Figure 2)A conductor gel (Manhattan Computer Products China)that imitated the pulpal tissue conductibility was injectedinto the pulp to ensure transfer of pulpal wall temperaturechanges to the thermocouple wire An orthodontic molarband (3M Unitek Monrovia CA USA) was applied to themolar tooth and bonded using multicure glass ionomerorthodontic band cement (3M Unitek Monrovia CA USA)The film thickness of the glass ionomer cement between thecrown and orthodontic band was approximately 25ndash35 120583m inaccordance with the literature [25] The space in the acrylicplatform was then filled with C-silicone impression material(Zhermack Zetaplus Rovigo Italy) to fix the cable in itsposition After this both lateral and occlusal radiograms(VarioDG Sirona BensheimGermany)were taken to ensurethat the wire was properly stabilized in its place (Figure 2)

Twenty pieces of 06mm diameter orthodontic stainlesssteel wire (Levanit Lewadental RemchingenGermany)werecut at 5 cm lengths and welded to the orthodontic bandusing the Nd YAG laser (Fidelis Plus III Fotona LjubljanaSlovenia) The study design is shown in Figure 3(a)

The Nd YAG laser parameters were as follows outputpower 940W frequency 1 Hz pulse duration 15ms work-ing distance 31mm spot diameter 06mm energy 940 Jfluency 2300 Jcm2 (Figure 4) To standardize the workingdistance an accessorial stick measuring 31mm in length wasattached to the laser probe (Figure 3(b)) The metal wirewelded to the molar band is shown in Figure 3(c) A smallpilot study demonstrated that three pulses are enough tosecurely weld the piece of wire and for standardizationthe welding process was performed with only three pulsesthroughout the study Compressed air was used after eachshut to restore the test sample to initial room temperature forstandardization

The J-type thermocouple wire was connected to a datalogger (XR440 Pocket Logger Pace Scientific NC USA)


(a) (b)


(a) (b) (c)





33

32

31

30

29

28

27

26

202 203 204

Thermocouple

20 OL UM MESIALPL1C

(∘C)

Tue 7 Sep 2010

















4 Conclusion





Acknowledgments


References





































Biomaterials












Journal of




















(a) (b)


(a) (b) (c)





33

32

31

30

29

28

27

26

202 203 204

Thermocouple

20 OL UM MESIALPL1C

(∘C)

Tue 7 Sep 2010

















4 Conclusion





Acknowledgments


References





































Biomaterials












Journal of
































4 Conclusion





Acknowledgments


References





































Biomaterials












Journal of




















Acknowledgments


References





































Biomaterials












Journal of


























Biomaterials












Journal of



















Documents

Research Article Temperature Changes of Pulp …downloads.hindawi.com/journals/tswj/2014/589461.pdfResearch Article Temperature Changes of Pulp Chamber during In Vitro Laser Welding