Experimental Study on Strength Evaluation Applied for Teeth Extraction: An In Vivo Study

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1 Sen Orers of Reprints at 2 The Open Dentistry Journal, 213, 7, 2-26 Open Access Experimental Stuy on Strength Evaluation Applie for Teeth Extraction: An In Vivo Stuy Marco Cicciù 1,*, Ennio Bramanti 2, Fabrizio Signorino 2, Alessanra Cicciù 2 an Francesco Sortino 3 1 Oral Surgery Meical Practitioner, Department of Human pathology, School of Dentistry, University of Messina School of Dentistry, ME, IT, USA 2 Resient Oontostomoatology Department, University of Messina, University of Messina School of Dentistry, ME, IT, USA 3 Surgical Meical Specialties Department, University of Catania Dental School, CT, IT, USA Abstract: Purpose: The aim of this work was to analyse all the applie movements when extracting healthy upper an lower jaw premolars for orthoontic purposes. The authors wante to emonstrate that the ifferent bone ensities of the manible an maxilla are not a significant parameter when relate to the extraction force applie. The buccal an palatal rocking movements, plus the twisting movements were also measure in this in-vivo stuy uring premolar extraction for orthoontic purposes. Methos: The physical strains or forces transferre onto the teeth uring extraction are the following three movements: gripping, twisting, an traction. A strain measurement gauge was attache onto an orinary entistry plier. The strain measurement gauge was constitute with an extensimetric washer with three 45º gris. The system operation was correlate to the variation of electrical resistance. Results: The variations of resistance ( R) an all the ifferent forces applie to the teeth ( V) were recore by a computerize system. Data results were processe through Microsoft Excel. The results unerline the stress istribution on the extracte teeth uring gripping, twisting an flexion. Conclusions: The obtaine ata showe that the strength require to effect teeth extraction is not influence by the quality of the bone but is instea influence by the shape of the tooth s root. Keywors: Twisting, Rocking, Gripping Movements, Tooth extraction, Strength, Dental Anatomy. INTRODUCTION Toay, the evolution of scientific ental knowlege gives clinicians the opportunity to save a tooth affecte by ifferent pathologies such as eep caries, tooth pulp inflammation or perioontal iseases. The association between moern enoontic an conservative techniques have meant that results are more preictable, with long-term clinical success while avoiing tooth extraction. However, tooth extraction is still inicate for those teeth which are consiere hopeless ; for large estructive caries; teeth with high mobility, or extractions association with orthoontic treatment. In aition, tooth extraction may represent one of the first oral surgery acts that a young entist will face at the beginning of his career [1-3]. Exoontia is the most common proceure performe in oral surgery an, as mentione before, is often the first surgical proceure carrie out by young entists. Complications, unexpecte clinical episoes in respect to regular *Aress corresponence to this author at the Department of Oral Surgery, Dental School, Messina University Via Consolare Valeria 981, Messina, Italy; Tel: ; Fax: ; acromarco@yahoo.it operative proceures uner normal circumstances, can increase morbiity [4, 5]. Even if tooth extraction complications are rare, their occurrence can create a prolonge treatment phase, often inucing iscomfort in the patient as well as causing further problems for the clinician. Prevention is the best way of avoiing future complications. Therefore, it is funamental that the clinician is able to evaluate the whole spectrum of complications an their implications. Complications can be wie ranging: from common ones like ry sockets or root fractures to uncommon an serious ones like isplacement of a root fragment into the maxillary sinus an its consequent oro-antral fistula [2, 5]. The instrumentation use to execute tooth extraction has been moifie over time [4-6]. Moern pliers are specific in shape an length for each tooth. The pliers use for tooth extraction can be consiere as the first type lever. Resistance is represente by the tooth while the power/force neee is containe within the operator s han strength [7]. Tooth extraction is a surgical act an several complications may arise irectly connecte to the operator s actions. Fracture of the alveolar bone is the most frequent complica / Bentham Open

2 Experimental Stuy on Strength Evaluation Applie The Open Dentistry Journal, 213, Volume 7 21 tion uring tooth extraction. This situation is connecte to too much force being transferre onto the tooth through the instrument. In aition, incorrect han movements can increase the possibility of tooth apex fracture. Other complications can be classifie in the pre or post operational phase. The breakage of basal bone or lower jaw islocation, swelling, eema an bleeing are all complications relate to the extraction proceure [8, 9]. Results have confirme that the bone resilience is connecte to the number of structural components an this parameter is influence by subsequent bone tissue moification, such as after tooth extraction [1, 11]. Other research work has evaluate tooth extraction through the recoring of the applie twisting movement an forces. It has been able to classify the rocking an twisting movements. The ata result showe, for the rocking movement, a high value for canine tooth extraction an a low value for the incisor. Moreover, the ifferent strength neee for the upper jaw compare to the lower jaw uring canine extraction has been highlighte [6, 12-14]. The rocking movement in tooth extraction has also been stuie in connection with the alveolar bone function an resistance. It has been emphasize that the strength applie in tooth extraction is irectly connecte to the functionality of the alveolar bone, the imension of the perioontal lamina an the angle of the root ivergence [4, 6, 13]. Therefore, an important connection between the extractive strength, an har an soft tooth tissues has been unerline. For this reason, correct geometric-shape pliers plays a funamental role in tooth extraction. Pliers with the correct shape an size can simplify extraction movements by reucing the applie strength neee [2, 4-6, 9, 14]. In this stuy we want to analyse the problems of tooth extraction relate to the force applie through the pliers. The quantification of the active forces use may be useful in avoiing future complications like alveolar bone or apex fractures. Careful attention to etails, incluing a thorough case history an anamnesis of the patient, raiographs an bloo investigations, are funamental treatment steps for exoontia. Before approaching tooth extraction, clinicians shoul evaluate the tooth root form an shape by raiographic image an clinical investigation. Consequently, the choice of instrument an surgical movements can then be ecie on, using all the information obtaine. MATERIALS AND METHODS The aim of this work is to analyse the actual strength use by an operator uring tooth extraction. High-tech gauges were applie onto ental pliers by a mechanical engineer in orer to quantify the stress istribution of tooth extraction. Three ifferent phases of extraction have been classifie an ivie as follow: Gripping Rocking Twisting 127 young patients (age years ol) were inclue in this stuy an 22 premolars teeth were extracte. All the selecte patients were receiving orthoontic treatment at the Catania Policlinic Meical Surgical Specialties Department. The patients parents signe consent forms after receiving a thorough explanation about the experiment, clinical proceures an possible risks. Both the consent forms an the research protocol were reviewe an approve by the Human Subject Review Committee from the University of Catania, Italy. The Orthoontist requeste the first upper an lower premolars extraction to create space an to complete the orthoontic treatment. No extracte tooth was affecte by perioontal inflammation or ental caries. The group of selecte patients was similar in, height, weight an age, an especially with regars to tooth root length an form (analyse by ental panoramic raiographic investigation). All extractions were performe by the same surgeon. Two ental premolar pliers, both for the upper an lower jaws, constitute the instrumental system. A mechanical screw-clamp system was applie onto each plier, near the part graspe by the operator. The clamp was use to lock the pliers in place when gripping the tooth. The angle obtaine represents the crown size. (Figs. 1-4). The strain gauge applie onto the pliers is an estensimetric washer with three gris in 45º types F L A The estensimetric washer was positione at the en of the pliers, precisely at 25mm from the centre of the pliers for the upper jaw, an at 2mm from the centre for of the lower jaw. The washer s electrical contacts were protecte by a silicone scabbar. The estensimetric washer was mae up of three estensimetres (gris of wires). These gris were superimpose to form a geometric system. The axis of the pliers hanle oriente one gri an it analyse the central component of the axial strength. The other gris were positione with a 45º inclination uring axis of the pliers hanle. These gris analyse the transversal component of the force in action. The tension of a material σ, can be efine as the strength applie on every mm² of material surface. The eformation of material ε, can be efine as the ratio between the variation of material length (uner a strength action), an the original length of the same material [15]. The ratio between superficial tension σ an material eformation ε can be calle elastic form an this value can be inicate with E (N/mm²) [15]. The system functionality is irectly connecte to the resistance variation of the washer gris. T The force use was converte into gri resistance uring tooth extraction., the analyses can be quantifie by a ifference between the resistance values of a Wheatstone brige [15-17]. The computerize system use was able to evaluate an quantify all tension variation in all the washer s gris. This variation is calle V. We calle ε the plier s eformation in the washer localization an we ientifie K as a constant (relate to the material quality of the washer). We obtaine V/V=Kε. The elastic moule form is E= σ/ε. Therefore with these consierations, V/V= σ/e * K where E represents the pliers elastic form an this is 21. N/mm².

3 22 The Open Dentistry Journal, 213, Volume 7 Cicciù et al. 1 a 2 a e c E tg c a (2a ) 1 tg sen Fig. (1). Scheme of the engineer formula for calculating force on manibular premolar plier. Fig. (2). Upper premolar plier use for the stuy. 25 LOWER JAW PLIERS SENSORS CONNECTION BASE CONNECTION WIRE UPPER JAW PLIERS 2 Fig. (3). Engineer mechanical moel for strength evaluating.

4 Experimental Stuy on Strength Evaluation Applie The Open Dentistry Journal, 213, Volume 7 23 Fig. (4). Scheme of the System of istribution ata Taking Palatal Rocking Buccal Rocking Different strenght involve in the stuy Clockwise C. irection clockwise irection Fig. (5). Evaluation of the total recore ata. THIS RELATIONSHIP IS TRUE FOR ALL GRID AN- GLES Numerous mathematical formulas between the han an pliers an between the pliers an tooth in the three types of strength movements were create. Some graphics were use to simplify the measurements of the force use. The graphics prouce a ifference for the upper an lower jaw. The orinate line represents the strength value in N; the abscissa line represents the tooth number accoring to international nomenclature. Using these mathematical formulas, two types of tensions were obtaine; the tension parallel to the hanle, an the tension orthogonal one. The changing of the three gris structure into the two irection system represente the real value of the strength istribution. SYMBOL DEFINITION σ = Tension of a Material ε = Material Deformation E = Ratio between Material Deformation an Tension of Material = ε/σ K = constant (epenent by material quality of washer). V = Variation N = Value for the strength measurement RESULTS The strength ata was recore with an electronic paper, elaborate in Microsoft Excel. Values of gripping, rocking, an twisting were classifie an table (Fig. 5). The average of the gripping values are 146 Nmm (9.81 Nmm about 1Kg). In particular, the average upper jaw gripping value is 165,6 Nmm, an the average lower jaw value is 126,4 Nmm. The strength in Nmm is note on the orinate lines, while the single value of the strength applie onto tooth (classifie by international nomenclature) is note in the abscissa lines (Figs. 6, 7). The rocking average was evaluate as follows: the rocking strength values were recore within a range of -2

5 24 The Open Dentistry Journal, 213, Volume 7 Cicciù et al. Number of teeth involve in the moment Manibular Rocking Fig. (6). Manibular rocking values recore. Number of teeth involve in the moment Maxillary Rocking Fig. (7). Maxillary rocking values recore. Number of teeth involve in the moment Maniboular Twisting Fig. (8). Manibular twisting values recore.

6 Experimental Stuy on Strength Evaluation Applie The Open Dentistry Journal, 213, Volume 7 25 Number of teeth involve in the moment Maxillary Twisting Fig. (9). Maxillary twisting values recore. Nmm an + 2 Nmm an istinctly into a range of -153,5 Nmm an + 266,3 Nmm for the upper jaw, an into a range of -18,1 Nmm an + 74,1 Nmm for the lower jaw (Figs. 7, 8). The twisting strength values were recore within a range of -2 Nmm an + 2 Nmm an fell into a range of - 4,1 Nmm an + 13, 9 Nmm for the upper jaw an 2,74 Nmm an +,22 Nmm for the lower jaw (Figs. 8, 9). The negative values of rocking graphics inicate the movements in the palatal irection an the negative value of twisting graphics represente the movements in a counter clockwise irection. DISCUSSION The results obtaine by this investigation were compare to the limite ata foun in the international literature. All results show that the strength use by the operator uring tooth extraction may be the most important factor that influences this surgical act. Several surgical etails, incluing proper patient preparation, asepsis, an meticulous management of har an soft tissue, haemostasis an aequate postoperative control, may help to reuce the rate of complications. Moreover, the controlle force use when applying surgical instruments is one of the most important factors to influence intraoperative complications [2, 4, 5, 7, 9, 12, 14]. In fact, the force use by the operator uring tooth extraction has previously been stuie [1-6]. In those stuies, the strength applie in tooth extraction on the lower jaw was recore an evaluate. The ifferent force use for ifferent tooth extraction was also analyse. Data has confirme that the rocking movement was high in canine extraction an low in incisor extraction [1-4]. In another stuy, Lehtinen an Ojala analyse the strength use in extraction of upper jaw teeth an confirme how the strength neee to extract superior or inferior canine teeth was not significantly ifferent [2, 4]. All factors an phases of tooth extraction were investigate in other papers in which the rocking movements, the functionality of alveolar bone, the length of perioontal lamina an the angle of roots are significant parameters to be taken into account by clinicians before carrying out extractions. Data presente in the literature confirms the ata obtaine in this stuy. The ifficulty in performing exoontia is higher when clinicians perform extraction of a tooth with two or more roots [1-4]. Results in other stuies have emonstrate that when there is a 2% loss of alveolar bone, the value of the rocking movement is not the same as in the extraction of high quality bone. The average of the rocking force value was small when the loss of alveolar bone was higher than 2% of the total alveolar bone volume. The root inclination an angle was an investigate parameter that may influence tooth extraction. This conition justifies why molar extraction is more ifficult than anterior single root incisor extraction. The ata results have shown how the presence of a ouble root in the upper premolar tooth increases the strength neee for the extraction. Maxillary bone is a low-ensity structure compare to manibular bone [17-22]. This stuy shows the result that the force applie by the operator uring tooth extraction shoul be constant when applie to similar teeth, however several factors may influence the nee to increase the strength use [2, 5, 18, 23, 24]. This stuy has also shown that the force require to have a controlle tooth extraction (expresse in N) is variable an specific to the operator: the active forces of twisting an rocking were always influence by the resistance of the tooth. Twisting an rocking values were ifferent for the upper an lower jaw ue to the fact that the superior premolar gives much more resistance because of the presence of a ouble root, which sometimes merge together. CONCLUSION This stuy was carrie out on teeth of young patients with a regular root formation an without any structural anomaly or shape alteration. The results of the stuy showe how the strength, neee for performing the first upper premolar extraction is 25 times higher than the lower jaw. This confirms that tooth extraction of multi-root teeth will result in a very ifficult surgical operation. The rocking movement recore high values of +199 Nmm while the twisting recore maximum values of +8,69 Nmm. This ata showe how the strength neee for ouble roote teeth extraction is not proportional to the strength neee for single ones.

7 26 The Open Dentistry Journal, 213, Volume 7 Cicciù et al. The complications of tooth extraction are connecte to an incorrect force application [18, 25]. Several factors, such as strange tooth anomalies, large root angles or strange root forms seem to be present when exoontia complications occur. However, bone structure an ensity o not influence the strength value. CONFLICT OF INTEREST The authors confirm that this article content has no conflicts of interest. ACKNOWLEDGEMENTS Authors woul like to express their gratitue to Prof Veronica Gavin, B.Sc; T.E.F.L. for her precious contribute on giving English language proof to this manuscript. REFERENCES [1] Ojala T. Rocking moments in the extraction of teeth in the lower jaw. Int J Oral Surg 198; 9: [2] Lehtinen R, Ojala T. Rocking an twisting moments in extraction of teeth in the upper jaw. Int J Oral Surg 198; 9: [3] Ojala T. Strain gauge measurements in connection with the extraction of teeth. Proc Finn Dent Soc 1972; 68: [4] Ojala T, Lehtinen R. The importance of alveolar bone loss, with of perioonatl space, visibility of lamina ura an ivergence of roots on the rocking moments in extraction of teeth in the lower jaw. Int J Oral Surg 198; 9: [5] Choi JP, Baek SH, Choi JY. Evaluation of stress istribution in resorbable screw fixation system: three-imensional finite element analysis of manibular setback surgery with bilateral sagittal split ramus osteotomy. J Craniofac Surg 21; 21(4): [6] Ojala T. Dental extraction movements an their action times. Strain gauge measurements of rocking an twisting movements in relation to tooth extraction, incluing observations on the length of the action time. Proc Finn Dent Soc 1984; 8(3): [7] Moore U, Durham J, Corbett I, Thomson P. The influence of staffing an timetabling on achieving competence in surgical extractions. Eur J Dent Euc 29; 13(1):15-9. [8] McRae M, Froel J. Miface fractures. Facial Plast Surg 2; 16(2): [9] Rana M, Gellrich NC, Ghassemi A, Gerressen M, Rieiger D, Moabber A. Three-imensional evaluation of postoperative swelling after thir molar surgery using 2 ifferent cooling therapy methos: a ranomize observer-blin prospective stuy. J Oral Maxillofac Surg 211; 69(8): [1] Ural A, Vashishth D. Interactions between microstructural an geometrical aaptation in human cortical bone. J Orthop Res 26; 24(7): [11] Summitt MC, Reisinger KD. Characterization of the mechanical properties of emineralize bone. J Biome Mater Res A 23; 67(3): [12] Seeman E. Reuce bone formation an increase bone resorption: rational targets for the treatment of osteoporosis. Osteoporos Int 23;14 (Suppl 3): S2-8. [13] Aeyemo WL, Oerinu HO, Oluseye SB, Taiwo OA, Akinwane JA. Inications for extraction of permanent teeth in a nigerian teaching hospital: a 16-year follow-up stuy. Nig Q J Hosp Me 28; 18(3): [14] Al-Khateeb TH, Alnahar A. Pain experience after simple tooth extraction. J Oral Maxillofac Surg 28; 66: [15] Risitano A. Mechanical esign. Boca Raton: Taylor & Francis Group 211; p [16] Gere JM, Goono BJ. Mechanics of materials. US: Cengage Learning 211; p [17] Risitano G, Cicciù M, Dini R, Franceschini G, Maiorana C. Evaluation of Strength in the "Toronto" Osseous-Prosthesis System. EPJ Web Of Conf 21; 6: ISSN:21-14X, oi: 1.151/epjconf/ [18] Hye TP. Extraction forceps for small hans. Br Dent J 1995; 179(1): [19] Vezeau PJ. Dental extraction woun management: meicationg postextraction sockets. J Oral Maxillofac Surg 2; 58(5): [2] Dennis MJ. Exoontia for the general entist: complications. Toays FDA 29; 21(1):14-9. [21] Suvinen TI, Messer LB, Franco E. Clinical simulation in teaching preclinical entistry. Eur J Dent Euc 1998; 2(1): [22] Aeyemo WL, James O, Ogunlewe MO, Laeine AL, Taiwo OA, Olojee AC. Inications for extraction of thir molars: a review of 1763 cases. Niger Postgra Me J 28; 15(1):42-6. [23] Koerner K. Practical ieas for ifficult extractions. Dent Econ 1992; 82(12): [24] Garcia GA, Sampero FG, Ganara RJ, Gallas MT. Trismus an pain after removal of impacte lower thir molars. J Oral Maxillofac Surg 1997; 55(11): [25] Cicciù M, Risitano G, Maiorana C, Franceschini G. Parametric analysis of the strength in the ''Toronto'' osseous-prosthesis system. Minerva Stomatol 29; 58(1-2): Receive: December 19, 212 Revise: January 17, 213 Accepte: January 3, 213 Cicciù et al.; Licensee Bentham Open. This is an open access article license uner the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricte, non-commercial use, istribution an reprouction in any meium, provie the work is properly cite.