A new method, applied for the first time in this research, was used for measurement of tooth extraction forces. The research has been done in a group of 50 examinees to whom the tooth extraction has been done with lower premolar forceps – forceps »13« and in the control group of 54 examinees in whom the tooth extraction has been done with upper incisive forceps – forceps »1«. The measurement instrument registered the extraction forces values in both types of forceps. There was no difference in any parameters in these two groups except in used pressure. While using the forceps »13«, a significantly lower tooth extraction force was measured than the force measured while using the forceps »1« (p<0.001). This means that in clinical work we can already apply noticeably less force using the lower premolar forceps for the extraction of the upper incisors (in the moments of rotation up to 70%). These results are meaningful, because they lead to better and improved instrument solutions and working techniques

Gordana Brumini

Ivana Brekalo

Juraj Ahel

Vladimir Ahel

English

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Coll. Antropol. 30 (2006) 1: 31–35Original scientific paperMeasurement of Tooth Extraction Forcesin Upper IncisorsVladimir Ahel¹, Ivana Brekalo², Juraj Ahel³ and Gordana Brumini4¹ Department of Oral and Maxillofacial Surgery, University Hospital Rijeka, Rijeka, Croatia2 Department of Dental Pathology, School of Medicine, University of Rijeka, Rijeka, Croatia3 Department of Surgery, University Hospital Rijeka, Rijeka, Croatia4 Department of Informatics, School of Medicine, University of Rijeka, Rijeka, CroatiaA B S T R A C TA new method, applied for the first time in this research, was used for measurement of tooth extraction forces. The re-search has been done in a group of 50 examinees to whom the tooth extraction has been done with lower premolar forceps– forceps »13« and in the control group of 54 examinees in whom the tooth extraction has been done with upper incisiveforceps – forceps »1«. The measurement instrument registered the extraction forces values in both types of forceps. Therewas no difference in any parameters in these two groups except in used pressure. While using the forceps »13«, a signifi-cantly lower tooth extraction force was measured than the force measured while using the forceps »1« (p<0.001). Thismeans that in clinical work we can already apply noticeably less force using the lower premolar forceps for the extractionof the upper incisors (in the moments of rotation up to 70%). These results are meaningful, because they lead to better andimproved instrument solutions and working techniques.Key words: tooth extraction forceps, tooth extraction forces, upper incisorsIntroductionForceps are probably the oldest tooth extraction in-strument, besides fingers. They were mentioned by Ari-stotel, Erasistrat, Celsius and Galen among the Romans.First more detalied descriptions of tooth extra- ction for-ceps can be found in »Chirurgicorum omnium« by Al-bucasis (936-1013)1–4. Throughout the history, the for-ceps were modified in their appearance and shape5–8. Thedevelopment of dentistry, dental materials and techni-ques, especially in the last 50 years, has not been fol-lowed by the tooth extraction techniques and instru-ments9–15.The reason for this stagnation lies in the fact thattooth extraction forces could not be measured and ex-pressed by mathematical relations. Extraction forces wereexpressed as strong, mild or moderate. In his work,Malden only qualitatively describes rotation forces andtooth dislocation9.A similar research was carried out in 1972 at Schoolof Dentistry of Tokyo. It should be mentioned that theexamination was done »in vitro«. The extracted teethwere put in a solid mass. Imitating the tooth extractionmovements, the appearing forces were followed and onthe basis of electric potential difference they were regis-tered on a graph paper. The disadvantage of this researchis the fact that in normal conditions there is an elasticconnection between the teeth and bones (our research)while in this research this connection is rigid, and there-fore decreases the importance and the result of work15.In 1980 Ojala and collaborators carried out the firstresearch on patients and went ahead with the first toothextraction measurement. They looked into the magni-tude and acting times of the rocking moments acting inbuccal and lingual direction by forceps. The main flawwas the fact that they didn’t measure the surface ofteeth, which is directly connected to the resistance whicha tooth puts up during the extraction. They measuredsize of the shift and time used up to carry throughout theintervention, which depends considerably on the capabil-ity of the operator16–19.Measurement of the extraction force in relation to thesurface of a tooth, making it as close to natural condi-31Received for publication August 28, 2005tions and using surface and force as mathematical mag-nitudes gives the scientific quality to this study.Due to the problems appearing in tooth extraction byusual instruments and methods, there was a need toevaluate the present forceps and extraction techniquesin order to improve the working efficacy and simplifysurgical procedures.This work's aim was to measure the mechanical forcesused in upper incisors extraction by lower premolar for-ceps and upper incisive forceps and suggest the most ade-quate tooth extraction forceps based on the efficacy ofteeth extraction forceps.MaterialsThe research involved 104 examinees operated by theauthor during the period between 2003–2004 with thestandard methods for extraction of upper incisors. All ofthem were referred to the Department of Oral andMaxillofacial Surgery of The University Hospital Rijeka,due to inability of tooth extraction in primary care units.Two groups were formed at random: the examined groupof 50 examinees to whom the upper incisors extractionwere done by lower premolar forceps – number »13« andthe control group of 54 examinees to whom the extrac-tions were done by forceps for upper incisive teeth –number »1«.All the examinees became acquainted with the kindand duration of the procedure, type of anesthetic, lengthof recovery, possible complications that might occure andthey gave their consent, according to ethical standardsapproved by The University Hospital Rijeka and MedicalFaculty of Rijeka.TeethThe research involved only teeth of normal mobilitylevel (level 1). The bone density, the quality of the sup-porting bone and number of periodontal fibers attachingthe tooth, can not be established precisely without so-phisticated methods, so the condition of supporting toothtissue was established by mobility degree.Before extraction we made x-rays to avoid any abnor-mality in root shape such as curvature, bulbosity andhypercementosis. Extraction resulted in fractured rootswe treated as a complication during the extraction, andthose results will be published in an article dealing withroot fracture forces caused by too much force applied onthe forceps handles.MethodsMeasurement of pressure forcesIn this paper extraction forces of upper incisive teethwere measured by a measuring instrument known as»Instrument for pressure and rotation measurement«. Itwas patented in 2003 in conformity with patent requestno. HR P20030692A, in the register of patents of the Of-fice for Intellectual Property20. According to interna-tional classification it was classified as G 01 D 21/00. Themeasuring instrument (Figure 1) functions in the waythat three-part air bags-silicone rubber (number 2) arepulled by the handles of forceps (number 1) through fore-seen cylindrical transitory holes (number 3). Then, withtooth extraction forceps we measure the pressure and ro-tation forces in the way that six air bags on two handlesare connected (number 4) with three manometers (num-ber 5). With the system of automatic manometer block-ing we can measure the maximal pressure force used onmanometer 2. The force used in rotation on the left andon the right is read on manometers 1 and 3. Obtainedvalues measured on manometers are expressed in bars,and they express the pressure force on the forceps han-dles. The pressure forces were measured on the handleson three manometers which were calibrated up to 1 bar.Manometers 1 and 3 measured left and right rotation,and manometer 2 measured tooth dislocation.Measurement of tooth surfaceThe extracted teeth had one root in order to simplifymeasurement. The surface of the tooth's root is directlyconnected with the extraction force due to the resistancewhich appears in tooth extraction.The root of the extracted tooth was measured on fivedifferent places with sliding scale. The tooth surface wasestablished by measured dimensions, inserting the val-ues in the formula for calculation of irregular cone sur-face.Statistical analysisThe normality of age data distribution was tested us-ing Kolmogorov – Smirinov test. Since the distributionV. Ahel et al.: Tooth Extraction Forces in Upper Incisors, Coll. Antropol. 30 (2006) 1: 31–35320,80,6 0,4 0,61 00,2 0,810,4 0,600,2 0,810,40,20542123Fig. 1. Instrument for pressure and rotation measurement. 1 –forceps, 2 – three-part air bags-silicone rubber, 3 – cylindric tran-sitory holes, 4 – connecting tubes, 5 – manometers.was not normal, we used the Mann-Whitney test to de-termine the differences in age among the tested groups.Pearson's 2 test was performed in order to test the dif-ferences in gender between the tested groups. One-wayANOVA was used to compare the differences in usedpressure between groups. We computed the correlationmatrix, using Pearson's product-moment correlation foranalysis of correlations between used pressure with theextraction forceps and tooth surface.All statistical analyses were performed with Statisticafor Windows (release 6.1., StaSoft. Inc., Tulsa, OK, USA).The level of statistical significance was set at 0.05.ResultsThe average total pressure (X±SD) determined by up-per incisive forceps-number »1« was significantly higherthan the one determined by lower premolar forceps –number »13« 1.11±0.28 bar vs. 0.66±0.19 bar, p<0.001(Table 1).There was no difference in gender between controlgroup and examined group; p=0.737 (Table 1). Also,there was no difference between control group and exam-ined group regarding to age, p=0.327, and the teeth sur-faces, p=0.071 (Table 1).Preassures measured by manometer 1 – left rotationmovements, manometer 2 – dislocation movements andmanometer 3 – right rotation movements, according totype of forceps were shown in Table 2.The pressure value determined by manometer 1 incontrol group-forceps »1«, was significantly higher thanin examined group-forceps »13«, 0.33±0.1 bar vs. 0.20±0.08, p<0.001 (Table 2). Pressures determined by ma-nometer 2 and manometer 3 in control group-forceps»1«, were also related to significantly higher values thenpressures determined in examined group-forceps »13«(Table2).In both groups Pearson's coefficient correlations werepositive and significant. In control group-forceps »1«(r=0.564, p<0.001). In examined group forceps »13« (r=0.298, p=0.036).With the increase of tooth surface, the used pressuresignificantly increased.Pearson's coefficient correlation for pressure deter-mined by manometer 2 in examined group- forceps »13«,was low and it wasn't significant (r=0.0221, p=0.123).But, coefficient correlation in control group-forceps »1«,was founded significant (r=0.563, p<0.001), indicatingthat teeth surfaces influenced on the pressure.In the examined group-forceps »13«, with the increaseof teeth surfaces, the used pressure increased, but notsignificantly (r=0.202, p=0.161).In the control group-forceps »1«, with the increase ofteeth surfaces, the used pressure significantly increased(r=0.549, p<0.001).DiscussionFor the first time in this paper tooth extraction forceswere measured »in vivo» and compared to tooth surface.The total pressure applied on forceps «13« – lower pre-molar was statistically lower than the total pressure ap-plied on forceps »1« – upper incisive (0.66 vs. 1.11 bar).The mean surface of the teeth extracted with the forceps»13« is not significantly different than the mean surfaceof the teeth extracted with the forceps »1« (13.71 mm2 vs.V. Ahel et al.: Tooth Extraction Forces in Upper Incisors, Coll. Antropol. 30 (2006) 1: 31–3533TABLE 1DEMOGRAPHIC CHARACTERISTICS, MEAN TEETH SURFACES AND OBTAINED PRESSURE REGARDING TO TYPE OF FORCEPSVariableControl groupForceps »1«Examined groupForceps »13« pNumber of subjects Number of subjectsGendermalefemale322228220.737Age, median, (range) 57 (28–79) 52 (12–76) 0.327Tooth surface (X±SD, mm²) 14.47±2.25 13.71±2.03 0.071Pressure (X±SD, bar) 1.11±0.28 0.66±0.19 <0.001TABLE 2RELATIONSHIP BETWEEN MEASURED PREASSURE ACCORDING TO MANOMETER 1, 2, 3 AND TYPE OF FORCEPSVariableControl groupForceps »1«(X±SD)Examined groupForceps »13«(X±SD)StatisticsF pManometer 1 (bar) 0.33±0.10 0.20±0.08 58.38 <0.001Manometer 2 (bar) 0.47±0.12 0.29±0.09 72.49 <0.001Manometer 3 (bar) 0.31±0.09 0.17±0.11 53.89 <0.00114.47 mm2). An additional examination was done by mea-suring the pressure force of each manometer separately,in single forceps. In the control group – forceps »1«, withthe increase of tooth surface, the used pressure also in-creased (p<0.05). It proves that in the forceps »1« – theupper incisive, the rotation movements – manometers 1and 3 are equally present as the dislocation movements –manometer 2. In the examined group, where lower pre-molar forceps were used in teeth extractions – forceps»13«, there were a significant difference between themovements of rotation and dislocation. A significantpressure increase with the increase of tooth surface wasmeasured only with manometer 1 (p<0.5). On manome-ters 2 and 3 the increased pressure in relation to the in-creased tooth surface was positive, that means that thepressure got stronger with increased tooth surface. How-ever, this connection was not statistically significant(p>0.05). It indicates that left rotation (manometer 1) isa predominant movement-collagen fibers in the relationtooth-bone are broken. Dislocation (manometer 2) androtation to the reverse side (manometer 3) are not sostrong, because the first rotation caused the destructionof most collagen fibers and the strength of teeth was sig-nificantly impaired.In the conclusion we emphasize that in our researchfor the first time mechanical forces, used in tooth extrac-tion, were measured »in vivo« with the »Instrument forpressure and rotation measurement«. On the basis of theeffectiveness of the tooth extraction forceps, we provedthat the pressure while using lower premolar forceps inupper incisors extraction is significantly lower than intooth extraction done with upper incisive forceps. It isimportant to mention that significantly lower force (inthe moment of rotation up to 70%) leads to the same ef-fect, but in some situations when the root extraction isnot possible with usual forceps for upper roots we avoidsurgical treatment of the tooth root removal.V. Ahel et al.: Tooth Extraction Forces in Upper Incisors, Coll. Antropol. 30 (2006) 1: 31–3534Fig. 2. Correlation between the tooth surface and measured pres-sure with manometer 1 regarding to forceps »1« and »13«.Fig. 3. Correlation between the tooth surface and the measuredpressure with manometer 2 regarding to forceps »1« and »13«.Fig. 4. Correlation between tooth surface and measured pressurewith manometer 3 regarding to forceps »1« and »13«.R E F E R E N C E S1. PIERLEONI, P., L. BOSSINI, P. BOSSINI, Minerva Stomatol., 34(1985) 595. — 2. CLARKE, J., J. Hist. Dent., 47 (1999) 11. — 3. ATKIN-SON, H., Aust. Dent. J., 47 (2002) 90. — 4. SIGRON, G., Schweiz. Mo-natsschr. Zahnmed., 95 (1985) 587. — 5. FOLEY, G., J. Am. Coll. Dent., 51(1984) 22. — 6. DE GUZMAN, P., Bull. Hist. Dent., 33 (1985) 90. — 7.ROSENTAL, E., J. Hist. Dent., 48 (2000) 60. — 8. FEE, E., T. BROWN, J.LAZARUS, P. THEERMAN, Am. J. Public Health, 92 (2002) 35. — 9.MALDEN, N., Dent. Update, 28 (2001) 41. — 10. HYDE, T., Br. Dent. J.,179 (1995) 26. — 11. LISENKOV, V., I. DEMIDOVA, Stomatologia, 77(1998) 12. — 12. JAVAHERI, D., J. GARIBALDI, J. Am. Dent. Assoc., 128(1997) 751. — 13. LEONARD, M., Dent. Today, 2 (2002) 38. — 14. MA-MEDOVA, L., Probl. Sotsialnoi Gig. Istor. Med., 1 (2000) 62. — 15. KA-WAMOTO, T., Shikwa Gakuho., 73 (1973) 59. — 16. LEHTINEN, R., T.OJALA, Int. J. Oral Surg., 9 (1980) 377. — 17. OJALA, T., Int. J. OralSurg., 9 (1980) 367. — 18. OJALA, T., R. LEHTINEN, Int. J. Oral Surg., 9(1980) 373. — 19. LEHTINEN, R., T. OJALA, Int. J. Oral Maxillofac.Surg., 15 (1986) 444. — 20. AHEL, V., M. [ARA^EVI], Patent No. HRP20030692A, (Dr`avni zavod za intelektualno vlasni{tvo, Zagreb, 2003).V. AhelDepartment of Oral and Maxillofacial Surgery, University Hospital Rijeka, T. Stri`i}a 3, 51000 Rijeka, Croatiae-mail: vladimir.ahel1@ri.htnet.hrMJERENJE SILA EKSTRAKCIJE GORNJIH INCIZIVAS A @ E T A KU ovom radu primijenjena je nova metoda za mjerenje sila ekstrakcije gornjih inciziva. Istra`ivanje je provedeno uskupini od 50 ispitanika kod kojih je ekstrakcija zuba izvr{ena donjim premolarnim klije{tima – klije{ta »13«, te ukontrolnoj skupini od 54 ispitanika gdje su za ekstrakciju zuba kori{tena gornja incizivna klije{ta – klije{ta »1«. Mjer-nim instrumentom utvr|ivane su vrijednosti sila ekstrakcija za oba tipa klije{ta. Pri upotrebi donjih premolarnih klije-{ta izmjerena je zna~ajno manja sila ekstrakcije od sile izmjerene kori{tenjem gornjih incizivnih klije{ta (p<0,001).Drugi prou~avani parametri u ove dvije skupine nisu se razlikovali. To ukazuje da u klini~kom radu ve} sada kori{te-njem donjih premolarnih klije{ta za ekstrakciju gornjih inciziva mo`emo koristiti zna~ajno manju silu, u momentimarotacije i do 70%. Rezultati ovog istra`ivanja zna~ajni su jer }e unaprijediti postoje}e instrumente i tehnike ekstrakcijezuba.V. Ahel et al.: Tooth Extraction Forces in Upper Incisors, Coll. Antropol. 30 (2006) 1: 31–3535

Measurement of Tooth Extraction Forces in Upper Incisors

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