Efectele negative ale fortelor ortodontice

Efectele negative ale fortelor ortodontice

Reactiile tesuturilor la deplasarea dentara ortodontica depinde in principal de modelul de distributie al raportului solicitare-deformare in tesuturile paradentale. Diferitele tipuri de deplasare dentara genereaza modele diferite de distributie a fortei si, prin urmare, diferite tipuri de reactii tisulare. Studii diferite, au evaluat reactiile tisulare prin mijloace radiologice si histologice si au depistat sechelele iatrogene ale fortei ortodontice. Aceste efecte includ leziuni odontale, gingivite, pierderi osoase marginale, reactii pulpare, resorbtii radiculare si reactii alergice la materialele din care sunt confectionate aparatele.

Problemele gingivale:

Efectele nocive ale aparatelor ortodontice fixe asupra parodontiului varieaza de la gingivite la pierderi osoase (Alexander SA. Effects of orthodontic attachments on the gingival health of permanent second molars. Am J Orthod Dentofacial Orthop 1991;100:337-40.) (Geiger AM. Mucogingival problems and the movement of mandibular incisors-a clinical review. Am J Orthod 1980;511-27.), (Dorfman HS. Mucogingival changes resulting from mandibular incisor tooth movement. Am J Orthod  978;74:286.). Cimentarea inelelor ortodontice si colarea ataselor pot provoca raspunsuri din partea tesuturilor moi locale (Huser MC, Baehni PC, Lang R, et al. Effects on orthodontic bands on microbiologic and clinical parameters. Am J Orthod Dentofacial Orthop 1990;97:213-8.). Aceste raspunsuri se datoreaza in principal acumularii de placa si proximitatii acestor accesorii de santul gingival (Alexander SA. Effects of orthodontic attachments on the gingival health of permanent second molars. Am J Orthod Dentofacial Orthop 1991;100:337-40.). Alte complicatii pe termen lung ale tratamentului ortodontic sunt retractiile gingivale. Diferiti autori au raportat un procent de aparitie a acestora cuprins intre 1,3% si 10%. Este larg acceptat faptul ca cel putin 2 mm de gingie keratinizata sunt necesari pentru a rezista fortelor ortodontice si a preveni retractiile (Geiger AM. Mucogingival problems and the movement of mandibular incisors-a clinical review. Am J Orthod 1980;511-27.). Dorfman (Dorfman HS. Mucogingival changes resulting from mandibular incisor tooth movement. Am J Orthod 978;74:286.) a sugerat ca incisivii mandibulari sunt dintii la nivelul carora apar cel mai probabil retractii gingivale ca raspuns la mecanoterapiea ortodontica. Acest fapt a fost atribuit grosimii reduse sau absentei tablei osoase vestibulare si absentei sau grosimii inadecvate a gingiei keratinizate care acopera dintii vestibularizati. Aceasta situatie clinica cu potential de risc necesita multa atentie, deoarece poate duce la efecte estetice necorespunzatoare, la sensibilitate radiculara, pierderi de sprijin parodontal, dificultate in mentinerea igienei orale, dificultati in vindecarile parodontale si susceptibilitate crescuta la carii

Tratamentul ortodontic deseori conduce la modificarea deprinderilor de igiena orala, ceea ce conduce la acumularea de placa si inflamatie gingivala. Dezvoltarea inflamatiee gingivale in timpul mecanoterapiei ortodontice este asociat a unor tipuri specifice bacteriene cum sunt cele enumerate in multe studii ((Huser MC, Baehni PC, Lang R, et al. Effects on orthodontic bands on microbiologic and clinical parameters. Am J Orthod Dentofacial Orthop 1990;97:213-8.), (Balenseifen JW, Madonia JV. Study of dental plaque in orthodontic patients. J Dent Res 1970;49:320-4.), (Corbett JA, Brown LR, Keene HJ, Horton IM. Comparison of streptococcus mutans concentrations in non-banded and banded orthodontic patients. J Dent Res 1981;60:1936-42.). Huser si colab. (Huser MC, Baehni PC, Lang R, et al. Effects on orthodontic bands on microbiologic and clinical parameters. Am J Orthod Dentofacial Orthop 1990;97:213-8.) au studiat longitudinal flora microbiana din placa pacientilor care suporta un tratament ortodontic. Au fost obtinute scoruri de placa si adancimi mai mari la sondaj la acesti pacienti comparativ cu lotul martor. Placa bacteriana a fost compusa in principal din spirochete si motile rods. Alti autori au raportat cresteri in nivelurile de bacteroides si de streptococi dupa colajul ortodontic (Balenseifen JW, Madonia JV. Study of dental plaque in orthodontic patients. J Dent Res 1970;49:320-4.), (Corbett JA, Brown LR, Keene HJ, Horton IM. Comparison of streptococcus mutans concentrations in non-banded and banded orthodontic patients. J Dent Res 1981;60:1936-42.). Se poate concluziona ca mecanoterapia ortodontica produce schimbarea ecosistemului oral local, modifica compozitia placii bacteriene in sensul dezvoltarii unui proces inflamator.

Resorbtiile radiculare:

In mod normal, cementul nu sufera resorbtii apreciabile, el pare a fi exclus de la activitatile asociate de remodelare  mentinerii homeostaziei calciului. Cu toate acestea, aplicarea fortei ortodontice poate declansa uneori resorbtia excesiva a cementului radicular, urmata de cea a dentinei si in cele din urma scurtarea radacinii, proces denumit resorbtie radiculara (Ferguson DB. Oral bioscience. China: Churchill livingstone; 1999.). Ottolengui (1914) (Ottolengui R. The physiological and pathological resorption of tooth roots. Item of Interest 1914;36:332-62.) si Ketcham (1927) (Ketcham AH. A preliminary report of an investigation of apical root resorption of vital permanent teeth. Int J Orthod 1927;13: 97-127.) au fost primii autori care au raportat prezenta resorbtiei radiculare severe asociate deplasarii ortodontice. Este una dintre sechelele de nedorit ale tratamentului ortodontic si cea mai putin previzibila. Ea poate sa apara in timpul desfasurarii tratamentului sau post-tratament faza, ridicand intrebari despre longevitatea dintilor tratati si stabilitatea rezultatelor tratamentului. Impreuna cu alti factori, fortele ortodontice pot initia si sustine procesele resorbtive (Krishnan V. Critical issues concerning root resorption: a contemporary review. World J Orthod 2005;6:30-40.). Jarabak si Fizzell, (Jarabak JR, Fizzell JA. Technique and treatment with light wire edgewise appliance. St Louis: C. V. Mosby; 1972.) dupa analizarea efectului sistemelor de forta din timpul mecanoterapiei, au concluzionat ca magnitudinea fortei ortodontice si fixare rigida a arcului in bracketuri ar putea fi considerate drept cei mai importanti factori predispozanti pentru resorbtia radiculara. Fortele de jiggling si de derotare reprezinta cauzele majore de resorbtie radiculara de cauza ortodontica (Alexander SA. Levels of root resorption associated with continuous arch and sectional arch mechanics. Am J Orthod Dentofacial Orthop 1996;110:21-4.), (Thompsun WJ. Current applications of Begg mechanics. Am J Orthod 1972;62:245-70.).

Comparand tratamentul mecanic cu si fara extractii dentare, au aparut corelatii certe intre tratamentul cu extractii si resorbtiile radiculare (Sameshima GT, Sinclair PM. Predicting and preventing root resorption- part II. Treatment factors. Am J Orthod Dentofacial Orthop 2001;119:11.), (McNab S, Battistutta D, Taverne A, Symons AL. External apical root resorption following orthodontic treatment. Angle Orthod 2000;77:227-32.), (Sharpe W, Reed B, Subtelny JD, Polson A. Orthodontic relapse, apical root resorption and crestal alveolar bone levels. Am J Orthod Dentofacial Orthop 1987;91:252-8.). Dintre diferitele deplasari ortodontice posibile, cele de intruzie si torq predispun cel mai mult radacina dintelui fenomenului de resorbtie (Sameshima GT, Sinclair PM. Predicting and preventing root resorption-part II. Treatment factors. Am J Orthod Dentofacial Orthop 2001;119:11.),(L'Abee EM, Saderink GC. Apical root resorption during Begg treatment. J Clin Orthod 1985;19:60-1.), Exista un consens in a afirma ca incisivii maxilari, in special incisivii centrali, sunt dintii cei mai predispusi acestui proces, urmati de molarii maxilari si canini. In arcul mandibular, dintii cei mai predispusi sunt incisivii laterali si centrali. S-a subliniat si faptul ca radacinile conice, comparativ cu cele rotunjite prezinta mai multe resorbtii (Beck BW, Harris EF. Apical root resorption in orthodontically treated subjects-analysis of edgewise and light wire mechanics. Am J Orthod Dentofacial Orthop 1994;105:350-61.), (Remington DN, Joondeph D, Artun J, Reidel RA, Chapko MK. Long-term evaluation of root resorption occurring during orthodontic treatment. Am J Orthod Dentofacial Orthop 1989;96:43-6.), (Sameshima GT, Asgarifer KO. Assessment of root resorption and root shape-periapicals vs panoramic films. Angle Orthod 2001;71:185-9.), (Linge L, Linge BO. Patient characteristics and treatment variables associated with apical root resorption during orthodontic treatment. Am J Orthod Dentofacial Orthop 1991;99:35-43.).

Alinierea caninilor inclusi reprezinta un factor de risc pentru aparitia resorbtiei (Linge L, Linge BO. Patient characteristics and treatment variables associated with apical root resorption during orthodontic treatment. Am J Orthod Dentofacial Orthop 1991;99:35 43.). Drogurile, precum si corticosteroizii si alcoolul, bolile sistemice, precum astmul si alergiile, predispun dintele resorbtiei radiculare dupa aplicarea fortelor ortodontice (Krishnan V. Critical issues concerning root resorption: a contemporary review. World J Orthod 2005;6:30-40.). Mai mult traumatismele dentofaciale in antecedente au fost propuse ca factori predispozanti (Linge L, Linge BO. Patient characteristics and treatment variables associated with apical root resorption during orthodontic treatment. Am J Orthod Dentofacial Orthop 1991;99:35-43.). Un studiu recent a sugerat ca ligamentul parodontal hipofunctional, asociat lipsei contactelor ocluzale dentare creste riscul de resorbtie radiculara ortodontica (Sringkarnboriboon S, Matsumoto Y, Soma K. Root resorption related to hypo functional periodontium on experimental tooth movement. J Dent Res 2003;82:486-90. ).

Brezniak si Wasserstein (Brezniak N, Wasserstein A. Orthodontically induced inflammatory root resorption-part II: clinical aspects. Angle Orthod 2002;72:180-4.) au clasificat resorbtiile radiculare in functie de gravitatea acestora. Por fi identificate formele: (1) cementare sau resorbtia de suprafata, caz in care numai straturile exterioare sunt resorbite, si pot fi pe deplin regenerate sau remodelate ulterior; (2), resorbtia dentinara cu reparatie, caz in care cementului si straturile exterioare ale dentinei sunt resorbite si sunt reparate, prin alterari morfologice; (3) resorbtie circumferentiala radiculara, caz in care se produce resorbtia completa a tesuturilor dure componente ale apexului radicular producandu-se scurtarea radacinii.

Cercetarile actuale ale resorbtiei radiculare ortodontice sunt indreptate spre identificarea genelor implicate in acest proces, a site-urillor lor cromozomiale (chromosome loci) si semnificatiei lor clinice. Al Qawasmi si colab. (Al-Qawasmi RA, Hartsfield JK Jr, Everett ET, Flury L, Liu L, Foroud TM, et al. Genetic predisposition to external apical root resorption. Am J Orthod Dentofacial Orthop 2003;123:242-52.) au raportat existenta unui legaturi intre dezechilibrul polimorfismului IL1β si alela 1 si resorbtiile radiculare apicale externe. Un alt studiu al acelorasi autori (Al-Qawasmi RA, Hartsfield JK Jr, Everett ET, Flury L, Liu L, Foroud TM, et al. Genetic predisposition to external apical root resorption: linkage of chromosome 18 marker. J Dent Res 2003;82:350-60.) si unul realizat de catre Low si colab. (Low E, Kharbanda O, Zoellner H, Darendeliler A. Genetic expression of RANK/RANKL and OPG during root resorption following orthodontic treatment. Available at: www.chs.usyd. edu.au/conf2002/minipost/av-low.pdf. Accessed Oct 1, 2005.)  leaga RANKL si OPG cu reglarea resorbtiei radiculare.

Progresul inregistrat in domeniul radiografiilor periapicale si panoramice este util in detectarea proceselor resorbtive aparute in timpul tratamentului (Remington DN, Joondeph D, Artun J, Reidel RA, Chapko MK. Long-term evaluation of root resorption occurring during orthodontic treatment. Am J Orthod Dentofacial Orthop 1989;96: 43-6.), (Sameshima GT, Asgarifer KO. Assessment of root resorption and root shape-periapicals vs panoramic films. Angle Orthod 2001;71:185-9.), (Linge L, Linge BO. Patient characteristics and treatment variables associated with apical root resorption during orthodontic treatment. Am J Orthod Dentofacial Orthop 1991;99:35-43.), (Janson GRP, Canto GDL, et al. A radiographic comparison of apical root resorption after orthodontic treatment with 3 different fixed appliance techniques. Am J Orthod Dentofacial Orthop 1999;118:262-73.), (Sameshima GT, Sinclair PM. Predicting and preventing root resorption-Part I Diagnostic factors. Am J Orthod Dentofacial Orthop 2001;119:505 10.). Ori de cate ori apare o astfel de problema se impune oprirea temporara a tratamentul ortodontic pentru 4-6 luni (Sameshima GT, Sinclair PM. Predicting and preventing root resorption-part II. Treatment factors. Am J Orthod Dentofacial Orthop 2001;119:11.), (Remington DN, Joondeph D, Artun J, Reidel RA, Chapko MK. Long-term evaluation of root resorption occurring during orthodontic treatment. Am J Orthod Dentofacial Orthop 1989;96: 43-6.), (Parker RJ, Harris EF. Directions of orthodontic tooth movements associated with apical root resorption of the maxillary central incisor. Am J Orthod Dentofacial Orthop 1998;114: 677 83.), (Copeland S, Green LJ. Root resorption in maxillary central incisors following active orthodontic treatment: Am J Orthod Dentofacial Orthop 1986;89:51-5.).

Oricare ar fi predispozitia sau factorii de influenta, majoritatea autorilor cred ca nu vor exista cresteri aparente ale resorbtiei dupa incetarea treatmentului ortodontic activ. (Remington DN, Joondeph D, Artun J, Reidel RA, Chapko MK. Long-term evaluation of root resorption occurring during orthodontic treatment. Am J Orthod Dentofacial Orthop 1989;96: 43-6.), (Linge L, Linge BO. Patient characteristics and treatment variables associated with apical root resorption during orthodontic treatment. Am J Orthod Dentofacial Orthop 1991;99:35-43.), (Copeland S, Green LJ. Root resorption in maxillary central incisors following active orthodontic treatment: Am J Orthod Dentofacial Orthop 1986;89:51-5.), (Levander E, Malmgren O. Long-term follow-up of maxillary incisor with root end resorption. Angle Orthod 2000;22:25-92.), (Linge BO, Linge L. Apical root resorption in upper anterior teeth. Eur J Orthod 1983;5:173-83.), (Barkana I, Narayanan AS, et al. Cementum attachment protein enriches putative cementoblastic populations on root surfaces in vitro. J Dent Res 2000;79:1482-8.). Unele reparatii au loc, inclusiv uniformizarea si remodelarea suprafetelor cementului si revenirea la normal a latimii ligamentului parodontal. Conturul original al radacinii si lungimea acesteia nu sunt niciodata restabilite, dar functia aparatului dentar nu este de obicei grav afectata de pierderea in lungime a radacinii. (Copeland S, Green LJ. Root resorption in maxillary centralincisors following active orthodontic treatment: Am J OrthodDentofacial Orthop 1986;89:51-5.).

Au fost propuse mai multe modalitati de a incetini ritmul resorbtiei radiculare in timpul mecanoterapiei ortodontice, inclusiv medicamente, hormoni, si factori de crestere. (Igarashi K, Adachi H, Mitani H, Shinoda H. Inhibitory effect of topical administration of a bisphosphonate (risedronate) on root resorption incident to orthodontic tooth movement in rats. J Dent Res 1996;75:1644-9.), (Liu L, Igarashi K, Haruyama N, Saeki S, Shinoda H, Mitani H. Effects of local administration of clodronate on orthodontic tooth movement and root resorption in rats. Eur J Orthod 2004;26:469-73.),(Villa PA, Oberti G, Moncada CA, Vasseur O, Jaramillo A, Tobon D, et al. Pulp-dentine complex changes and root resorption during intrusive orthodontic tooth movement in patients prescribed nabumetone. J Endod 2005;31:61-6.), (Loberg EL, Engstrom C. Thyroid administration to reduce root resorption. Angle Orthod 1994;64:395-9.), (Poumpros E, Loberg E, Engstrom C. Thyroid function and root resorption. Angle Orthod 1994;64:389-93. Shirazi M, Dehpour AR, Jafari F. The effect of thyroid hormone on orthodontic tooth movement in rats. J Clin Pediatr Dent 1999;23:259-64.). Intr-un experiment recent, Bialy si colab. (Bialy TE, El-Shamy I, Graber TM. Repair of orthodontically induced root resorption by ultrasound is humans. Am J Orthod Dentofacial Orthop 2004;126:186-93.) au studiat efectul aplicarii de ultrasunete sub forma unor impulsuri de mica intensitate in vindecarea resorbtiei radiculare induse ortodontic . Rezultatele au fost promitatoare, demonstrand o reducere a resorbtiei radiculare si accelerarea procesului de vindecare in site-urile de resorbtie cementare dupa 4 saptamani de aplicare a acestor ultrasunete

Reactii pulpare:

Diverse proceduri dentare, inclusiv de deplasare ortodontica dentara, pot afecta negativ pulpa dentara. Literatura de specialitate arata rezultate contradictorii cu privire la aparitia incidentelor pulpare ca urmare a aplicarii fortelor ortodontice. Unele studii au sugerat posibilitatea aparitiei unor daune permanenta ale tesutului pulpar datorita fortei ortodontice, altele sustinut ca nu exista efecte semnificative de lunga durata la nivelul pulpei dentare (Unsterseher RE, Nieberg LG, Weimer AD, Dyer JK. The response of human pulpal tissue after orthodontic force application. Am J Orthod Dentofacial Orthop 1987;92:220-4.). In 1980, Labart  si colab. (Labart WA, Taintor JF, Dyer JK, Weimer AD. The effect of orthodontic forces on pulp respiration in the rat incisor. J Endod 1980;6:724-7.) au demonstrat o crestere a ratei de respiratie pulpara prin experimente efectuate pe incisivi de soareci (de 1-2 ori mai mult decat pe lotul de control), atunci cand acesti dinti sunt suputi stresului ortodontic timp de 72 de ore. Harmersky si colab. (Hamersky PA, Weimer AD, Taintor JF. The effect of orthodontic force application on pulpal tissue respiration rate in the human premolar. Am J Orthod 1980;77:368-78.) au aratat ca se produce o scadere in rata respiratorie pulpara dupa aplicarea fortei ortodontice la om. Unsterseher si colab. (Unsterseher RE, Nieberg LG, Weimer AD, Dyer JK. The response of human pulpal tissue after orthodontic force application. Am J Orthod Dentofacial Orthop 1987;92:220-4.) au obtinut aceleasi rezultate.

In ultimii ani, modificarile in vascularizatia pulpara si fluxul sanguin ca raspuns la forta ortodontica au fost obiect de studiu. Diverse experimente au demonstrat o scadere initiala in fluxul de sange, pe o durata de aproximativ 32 minute, urmata de o crestere a fluxului de sange (pentru 48 de ore). Mostafa si colab. (Mostafa YA, El-Mangoury NH. Iatrogenic pulpal reactions to orthodontic extrusion. Am J Orthod Dentofacial Orthop 1991; 99:30-4.) au raportat aglomerarea si dilatarea vaselor de sange si edemul din tesutul pulpar in observatiile lor histologice. Un studiu histomorfometric efectuat pe soareci al lui Nixon si colab. (Nixon CE, Saviano JA, King GJ, Keeling SD. Histomorphometric study of dental pulp during orthodontic tooth movement. J Endod 1993;19:13-6.) contrazic unele studii anterioare ei raportand o crestere a numarul de vase functionale pulpare dupa aplicarea fortei ortodontice. Derringer si Linden, (Derringer KA, Jaggers DC, Linden RWA. Angiogenesis in human dental pulp following orthodontic tooth movement. Dent Res 1996;75:1761-6.) care au aratat ca exista o crestere in factorii de crestere angiogenici in pulpa dentara, au sprijinit acest rezultat. Un studiu recent a lui Derringer si colab. (Derringer KA, Linden RWA. Vascular endothelial growth factor, fibroblast growth factor 2, platelet derived growth factor and transforming growth factor beta released in human dental pulp during orthodontic force. Arch Oral Biol 2004;49:631-41.) a identificat factorii de crestere angiogenici specifici eliberati ca raspuns la forta ortodontica, factorul de crestere endotelial vascular, FGF-2, PDGF si-TGFβ.

Referat: Dieta - sugestii Document online: Determinarea clorurii de sodiu din produsele din carne

Impactul clinic al tuturor acestor studii este acela ca daca s-ar determina orice modificare din tesut pulpar aceasta ar putea pune in pericol vitalitatea pe termen lung a dintilor. Progresia procesului inflamator in pulpa dentara umana aparent depinde de stimularea de catre neuropeptide a fibroblastilor si de productia de citokine inflamatorii, precum IL-1, IL-3, IL-6, si TNFα. Un studiu recent descrie apoptoza din tesuturile pulpei dentare ale soarecilor in cursul treatmentului ortodontic (Yamaguchi M, Kojima T, Kanekawa M, Aihara N, Nogimura A, Kasai K. Neuropeptides stimulate production of interleukin 1 β, interleukin 6 and tumor necrosis factor in human dental pulp cells. Inflamm Res 2004;53:199-204.). Perinetti si colab.( Perinetti G, Varvara G, Festa F, Esposito P. Asparatate aminotransferase activity in pulp of orthodontically treated teeth. Am J Orthod Dentofacial Orthop 2004;125:88-92.) au demonstrat ca o enzima, aspartat aminotransferaza (care este eliberata extracelular la moartea celulei), este semnificativ crescuta dupa aplicarea fortei ortodontice.

Schimbarile posttratament:

Fortele ortodontice sunt cunoscute pentru producea de zone de presiune si tensiune in ligamentul parodontal si osul alveolar. Acesta solicitare modifica vascularizatia tesuturilor afectate si debitul sanguin oferind un micromediu favorabil fie pentru depunerea de tesut fie pentru resorbtie. Murrell si colab. (Murrell EF, Yen EH, Johnson RB. Vascular changes in the periodontal ligament after removal of orthodontic forces. Am J Orthod Dentofacial Orthop 1996;110:280-6.) au raportat ca incetarea fortelor ortodontice produce schimbari semnificative in numarul si densitatea vaselor de sange ale ligamentului parodontal. Normalizarea vascularizatiei parodontale a fost observata dupa un interval de timp, echivalent cu durata de aplicare a fortei ortodontice, si s-a sugerat ca este una dintre cauzele principale ale recidivei.

Nakanshi si colab. (Nakanishi H, Seki Y, Kohno T, Muramoto T, Toda K, Soma K. Changes in response properties of periodontal mechanoreceptors after experimental orthodontic tooth movement in rats. Angle Orthod 2004;74:93-9.) au raportat ca particularitatile de raspuns ale mecanoreceptorilor parodontale sunt adaptate pozitiei recent dobandite a dintilor. Dupa 7 zile de la indepartarea fortei, aranjamentul fibrelor de colagen devine foarte asemanator cu cel al grupului de control. Yoshida si colab. (Yoshida Y, Yoshida Y, Sasaki T, Yokoya K, Hiraide T, Shibasaki Y. Cellular roles in relapse processes of experimentally moved rat molars. J Electron Microsc 1999;48:147-57.) au evaluat in experiente efectuate pe soareci raspunsurile celulare din recidiva molarilor deplasati experimental si au sugerat ca remodelarea rapida a ligamentului parodontal si osului alveolar dupa tratament, pot fi identificate drept cauza principala a recidivei. Un raport recent a aratat ca, dupa deplasarea dentara, fortele ocluzale au fost factori majori in promovarea si accelerarea recuperarii parodontale (Terespolsky M, Brin I, Steigman S. The effect of functional occlusal forces on orthodontic tooth movement and tissue recovery in rats. Am J Orthod Dentofacial Orthop 2002;121: 620-8..). Se afirma ca diferitele tipuri de leziuni dentare si ligamentare produse de mecanoterapia ortodontica se vindecca mai rapid si pe zone mai extinse in cazul dintilor functionali. In timpul perioadei de contentie, revenirea la dimensiunile parodontale normale este reglata de rata si directia turnoverului osului alveolar (King GJ, Latta L, Ruttenberg AO, Keeling SD. Alveolar bone turnover and tooth movement in male rats after removal of orthodontic appliances. Am J Orthod Dentofacial Orthop 1997; 111:266-75.).

Experiente pe oameni despre influenta magnitudinii fortei asupra deplasarii dentare -sursa Ren Y. Age effect on orthodontic tooth movement, Nijmegen, 2003 [Thesis].

Storey E, Smith R. Force in orthodontics and its relation to tooth movement. Aust Dent J 1952;56:11-18.

Lee BW. Relationship between tooth-movement rate and estimated pressure applied. J Dent Res 1964;44:1053.

Andreasen GF, Zwanziger D. Experimental findings on tooth movement under two conditions of applied force. Angle Orthod. 1967;37:9-12.

Hixon EH, Atikian H, et all. Optimal force, differential force, and anchorage. Am J Orthod 1969;55:437-457.

Hixon EH, Aaasen TO, et all. On force and tooth movement. Am J Orthod, 1972;62:476-489.

Boester CH, Johnston LE. A clinical investigation of the concept of differential and optimal force in canine retraction. Angle Orthod. 1972;44:113-119.

Andreasen GF, Zwanziger D. A clinical evaluation of the differential force concept as applied to the edgewise bracket. Am J Orthod. 1980;88:252-260.

Lee BW. The force requirement for tooth movement part 1:tipping and bodily mouvement. Aust Orthod J, 1995;13:238-248.

Owmann-Moll P, Kurol J, Lundgren D. Effect of a doubled orthodontic force magnitude on tooth movement and root resorbtion. An inter-individual study in adolescents.Eur J Orthod 1996a;18:141-150.

Owmann-Moll P, Kurol J, Lundgren D. Effect of a four-fold orthodontic force magnitude on tooth movement and root resorbtion. An inter-individual study in adolescents.Eur J Orthod 1996b;18:287-94.

Lundgren D, Owmann-Moll P, Kurol J. Early tooth movement pattern after application of a contolled continuous orthodontic force. A human experimental model.Am J Orthod Dentofacial Orthop, 1996;110:287-295.

Iwasaki L, Haack, et al. Human tooth movement in response to continuous stress of low magnitude. Am J Orthod Dentofacial Orthop, 2000;117:175-183.

Tot despre forta:

Masuratori in vivo cu privire la forta produsa de activarea arcurilor a aratat ca forta initiala scade cu 20% dupa trei zile (Lundgren D, Owmann-Moll P, et al. Accuracy of orthodontic force and tooth movement measurements. Br J Orthod, 1996b;23:241-248). Alte studii care au confirmat scaderea fortei dupa cateva zile sunt cele ale lui Kurol si colab (1996b) (Kurol J, Owmann-Moll P, Lundgren D. Time-related root resorbtion after application of a controlled continuous orthodontic force. Am J Orthod Dentofacial Orthop 1996b;110:303-310.), Lundgren (1996a) (Lundgren D, Owmann-Moll P, Kurol J. Early tooth movement pattern after application of a contolled continuous orthodontic force. A human experimental model.Am J Orthod Dentofacial Orthop, 1996;110:287-295.) si Owmann-Moll si colab. (1995, 1996a,b) (Owmann-Moll P, Kurol J, Lundgren D. Continuous versus interrupted continuous orthodontic force related to early tooth movement and root resorbtion. Angle Orthod 1995;65:395-402.), (Owmann-Moll P, Kurol J, Lundgren D. Effect of a doubled orthodontic force magnitude on tooth movement and root resorbtion. An inter-individual study in adolescents.Eur J Orthod 1996a;18:141-150.), (Owmann-Moll P, Kurol J, Lundgren D. Effect of a four-fold orthodontic force magnitude on tooth movement and root resorbtion. An inter-individual study in adolescents.Eur J Orthod 1996b;18:287-94.).