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1_{Associate Professor, Department of Orthodontics, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece.} 2_{Associate Professor and Program Coordinator, Department of Orthodontics, School of Dentistry, Aristotle University of Thessaloniki,}

Thessaloniki, Greece.

3_{Doctor of Dentistry, Department of Endontology, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece.}

A

ABBSSTTRRAACCTT

AIM: The aim of this review is the presentation and critical analysis of the mechanical factors associated with orthodontic treatment and implicated in the formation of root resorption.

METHOD: Original articles and reviews pertaining to this topic were searched at the data base PubMed until May 2009.

FINDINGS: Root resorption shows considerable vari-ations. Individuals may present minimal or signifi-cant resorption, more than 3 mm while a percentage of 5% may present more than 5 mm. The magnitude of forces applied by the orthodontist seems to be among the mechanical factors that may affect the formation of resorptions, while intrusion and jig-gling seem to be the most harmful among the teeth movement types. Teeth resorptions also seem to be associated with the type and duration of the applied forces, the range of tooth movement, as well as with genetic and biological factors, rendering this way the dissociation and the degree of participation of these factors in the appearance of resorptions par-ticularly difficult.

CONCLUSIONS: Root resorptions of teeth are an unanticipated phenomenon of multifactorial etiolo-gy. Up until now, it seems that there is not enough evidence that could lead to specific strategies effi-cient to minimize or prevent the phenomenon of root resorption. ¶ ¶EEPPII§§HHææHH ™∫√¶√™: ªÂ ÙËÓ ·ÚÔ‡Û· ·Ó·ÛÎfiËÛË ÂȯÂÈÚÂ›Ù·È ÌÈ· ÚÔÛ¿ıÂÈ· ÂÈηÈÚÔÔ›ËÛ˘, Î·È ÎÚÈÙÈ΋˜ ·Ó¿Ï˘Û˘ ÙˆÓ Ì˯·ÓÈÎÒÓ ·Ú·ÁfiÓÙˆÓ Ô˘ Û¯ÂÙ›˙ÔÓÙ·È Ì ÙËÓ ÔÚıÔ‰ÔÓÙÈ΋ ıÂÚ·›· Î·È ÂÓÔ¯ÔÔÈÔ‡ÓÙ·È ÁÈ· ÙË ‰ËÌÈÔ˘ÚÁ›· ·ÔÚÚÔÊ‹ÛÂˆÓ ÙˆÓ ÚÈ˙ÒÓ ÙˆÓ ‰ÔÓÙÈÒÓ. ª∂£√¢√™: ¶ÚˆÙfiÙ˘· ¿ÚıÚ· Î·È ·Ó·ÛÎÔ‹ÛÂȘ Ô˘ ·ÊÔÚÔ‡Ó ÙÔ ı¤Ì·, ·Ó·˙ËÙ‹ıËÎ·Ó ÛÙË ‚¿ÛË ‰Â‰ÔÌ¤ÓˆÓ PubMed ̤¯ÚÈ ÙÔÓ ª¿ÈÔ ÙÔ˘ 2009. ∂Àƒ∏ª∞∆∞: ∏ ·ÔÚÚfiÊËÛË ÙˆÓ ÚÈ˙ÒÓ ·ÚÔ˘ÛÈ¿˙ÂÈ ÛËÌ·ÓÙÈΤ˜ ‰È·Î˘Ì¿ÓÛÂȘ. ∆· ¿ÙÔÌ· ÌÔÚ› Ó· ÂÌÊ·Ó›˙Ô˘Ó ÂÏ¿¯ÈÛÙË, ‹ ÛËÌ·ÓÙÈ΋ ·ÔÚÚfiÊËÛË, ÂÚÈÛÛfiÙÂÚË ·fi 3 mm, ÂÓÒ ÔÛÔÛÙfi 5% ÌÔÚ› Ó· ·ÚÔ˘ÛÈ¿ÛÂÈ ÂÚÈÛÛfiÙÂÚÔ ·fi 5 mm. ªÂٷ͇ ÙˆÓ Ì˯·ÓÈÎÒÓ ·Ú·ÁfiÓÙˆÓ Ô˘ ÌÔÚ› Ó· ÂËÚ¿ÛÔ˘Ó ÙËÓ ·Ó¿Ù˘ÍË ÙˆÓ ·ÔÚÚÔÊ‹ÛˆÓ, Ê·›ÓÂÙ·È Ó· Â›Ó·È ÙÔ Ì¤ÁÂıÔ˜ ÙˆÓ ‰˘Ó¿ÌÂˆÓ Ô˘ ·ÛÎÔ‡ÓÙ·È ·fi ÙÔÓ ÔÚıÔ‰ÔÓÙÈÎfi, ÂÓÒ ·fi ÙȘ ηÙ¢ı‡ÓÛÂȘ ÌÂٷΛÓËÛ˘ ÙˆÓ ‰ÔÓÙÈÒÓ Ë ÂÌ‚‡ı˘ÛË Î·È ÔÈ ÎÈÓ‹ÛÂȘ ·ÏÈÓ‰ÚÔÌÈÎÔ‡ Ù‡Ô˘ Ê·›ÓÂÙ·È Ó· Â›Ó·È ÔÈ ÈÔ ÂÈ‚Ï·‚›˜. √È ·ÔÚÚÔÊ‹ÛÂȘ ÙˆÓ ‰ÔÓÙÈÒÓ Ê·›ÓÂÙ·È ·ÎfiÌË Ó· Â›Ó·È Û˘Ó‰Â‰Â̤Ó˜ Ì ÙÔ Â›‰Ô˜ ÙˆÓ ·ÛÎÔ˘Ì¤ÓˆÓ ‰˘Ó¿ÌˆÓ, ÙË ¯ÚÔÓÈ΋ ‰È¿ÚÎÂÈ· Ù˘ ·ÛÎÔ‡ÌÂÓ˘ ‰‡Ó·Ì˘, ÙËÓ ¤ÎÙ·ÛË Ù˘ ÌÂٷΛÓËÛ˘ ÙÔ˘ ‰ÔÓÙÈÔ‡, ·ÏÏ¿ Î·È Ì ÁÂÓÂÙÈÎÔ‡˜ Î·È ‚ÈÔÏÔÁÈÎÔ‡˜ ·Ú¿ÁÔÓÙ˜, ηıÈÛÙÒÓÙ·˜ ¤ÙÛÈ È‰È·›ÙÂÚ· ‰‡ÛÎÔÏÔ ÙÔ ‰È·¯ˆÚÈÛÌfi Î·È ÙÔ ‚·ıÌfi Û˘ÌÌÂÙÔ¯‹˜ ÙˆÓ ·Ú·ÁfiÓÙˆÓ ·˘ÙÒÓ, ÛÙËÓ ÂΉ‹ÏˆÛË ÙˆÓ ·ÔÚÚÔÊ‹ÛˆÓ. ™Àª¶∂ƒ∞™ª∞∆∞: √È ·ÔÚÚÔÊ‹ÛÂȘ ÙˆÓ ÚÈ˙ÒÓ ÙˆÓ

∂ ∂ππ™™∞∞°°øø°°∏∏ ∏ ·ÔÚÚfiÊËÛË ÙˆÓ ÚÈ˙ÒÓ ÙˆÓ ‰ÔÓÙÈÒÓ Â›Ó·È Ì›· ·ÓÂ-Èı‡ÌËÙË, ȉȷ›ÙÂÚ· ÂÚ›ÏÔÎË Î·È ÌË ·ÓÙÈÛÙÚÂÙ‹ ·ıÔÏÔÁÈ΋ ‰È·‰Èηۛ·, Ô˘ ¤¯ÂÈ Û˘Ó‰Âı› ¿ÌÂÛ· Ì ÙËÓ ÔÚıÔ‰ÔÓÙÈ΋ ıÂÚ·›·. ªÔÚ› Ó· ·ÊÔÚ¿ Ù· Â͈-ÙÂÚÈο ÛÙÚÒÌ·Ù· Ù˘ ÔÛÙ½Ó˘, Ù˘ Ô‰ÔÓÙ›Ó˘ Ù˘ Ú›˙·˜, ‹ Î·È ÙÔ ·ÎÚÔÚÚ›˙ÈÔ (Bakland, 1992; Brezniak Î·È Wasserstein, 2002a). ŒÙÛÈ, ·Ó¿ÏÔÁ· Ì ÙÔ ‚·ıÌfi ·ÔÚ-ÚfiÊËÛ˘, Â›Ó·È ‰˘Ó·ÙfiÓ Ó· ÚÔÎÏËı› Ì›ˆÛË ÙÔ˘ Ì‹ÎÔ˘˜ Ù˘ Ú›˙·˜ ÙˆÓ ‰ÔÓÙÈÒÓ Î·È ¤ÓÙÔÓË ÎÈÓËÙÈÎfiÙËÙ· Ì Â·ÎfiÏÔ˘ıÔ Ó· ‰È·Î˘‚‡ÂÙ·È ÙfiÛÔ Ë ÔÚıÔ‰ÔÓÙÈ΋ ıÂÚ·›· fiÛÔ Î·È Ë ÛÙ·ıÂÚfiÙËÙ· ÙÔ˘ ıÂÚ·¢ÙÈÎÔ‡ ·ÔÙÂϤÛÌ·ÙÔ˜. ∞ÔÙÂÏ› Û˘ÓÂÒ˜ ¤Ó· ·fi Ù· ϤÔÓ ·ÓÂÈı‡ÌËÙ· Û˘Ì‚¿Ì·Ù·, ÙfiÛÔ Î·Ù¿ ÙËÓ ‰È¿ÚÎÂÈ· fiÛÔ Î·È ÛÙÔ ¤Ú·˜ Ù˘ ÔÚıÔ‰ÔÓÙÈ΋˜ ıÂÚ·›·˜, ÂÓÒ ·ÎfiÌË ı· ÌÔÚÔ‡Û ӷ ·ÔÙÂϤÛÂÈ ÛÙÔÈ¯Â›Ô Î·Îԉȷ¯Â›ÚÈÛ˘ ÙÔ˘ ·ÛıÂÓÔ‡˜ Ì Â·ÎfiÏÔ˘ı· ËıÈο, ÔÈÎÔÓÔÌÈο Î·È ÓÔÌÈο. ∫ÏÈÓÈΤ˜ ¤Ú¢Ó˜ ¤¯Ô˘Ó ηٷÁÚ¿„ÂÈ ·ÔÚÚfiÊËÛË ÚÈ˙ÒÓ Û fiÏ· Ù· ‰fiÓÙÈ·, ˆÛÙfiÛÔ, ÌÂÁ·Ï‡ÙÂÚË Û˘¯Ófi-ÙËÙ· Î·È ÌÂÁ·Ï‡ÙÂÚÔ ‚·ıÌfi ·ÔÚÚfiÊËÛ˘ ÂÌÊ·Ó›˙Ô˘Ó ÔÈ Ï¿ÁÈÔÈ Î·È ÎÂÓÙÚÈÎÔ› ¿Óˆ Î·È ÔÈ Î¿Ùˆ ÙÔÌ›˜ (∂ÈÎfi-Ó· 1) (Levander Î·È Malmgren, 1988; Remington Î·È Û˘Ó. 1989; Kaley Î·È Phillips, 1991; Beck Î·È Harris, 1994; Alexander, 1996; Janson Î·È Û˘Ó., 2000; Apajalahti Î·È Peltola, 2007). ∆Ô Â‡ÚÔ˜ Ù˘ ·ÔÚÚfiÊËÛ˘ ÙˆÓ ÚÈ˙ÒÓ ÙˆÓ ‰ÔÓÙÈÒÓ ·ÍÈÔÏÔÁ‹ıËΠηٿ ηÈÚÔ‡˜ ÔÛÔÙÈο Î·È ÔÈÔÙÈο, Ì ‰È¿ÊÔÚ˜ ÌÂıÔ‰ÔÏÔÁ›Â˜ Î·È ·ÂÈÎÔÓÈÛÙÈΤ˜ Ù¯ÓÈΤ˜. √È Û¯ÂÙÈΤ˜ ÌÂϤÙ˜ Û˘Ó¤ÎÚÈÓ·Ó ÙÔ Ì‹ÎÔ˜ Ù˘ Ú›˙·˜ ÙˆÓ ‰ÔÓÙÈÒÓ ÚÈÓ Î·È ÌÂÙ¿ ÙËÓ ÔÚıÔ‰ÔÓÙÈ΋ ıÂÚ·›· Ì ¯Ú‹ÛË Ï¿ÁÈˆÓ ÎÂÊ·ÏÔÌÂÙÚÈÎÒÓ ·ÎÙÈÓÔÁÚ·ÊÈÒÓ (Copeland Î·È Green, 1986; McFadden Î·È Û˘Ó., 1989; Harris Î·È Baker, 1990; Parker Î·È Harris, 1998; Horiuchi Î·È Û˘Ó., 1998), ·ÓÔÚ·ÌÈÎÒÓ ·ÎÙÈÓÔÁÚ·ÊÈÒÓ (Brin Î·È Û˘Ó., 1991; Apajalahti Î·È Peltola, 2007;

IINNTTRROODDUUCCTTIIOONN

Root resorption of teeth is an undesirable, particularly complicated and non reversible pathologic process, direct-ly associated with orthodontic treatment. It may be relat-ed to the external layers of cementum, the dentine of the root, or the apex (Bakland, 1992; Brezniak and Wasser-stein, 2002a). Thus, depending on the amount of resorp-tion, a reduction of the root length and profound mobili-ty may be induced with a consequent risk of the ortho-dontic treatment and the stability of treatment result. Therefore, it forms one of the most undesirable incidents during as well as at the end of the orthodontic treatment, whereas it could also form an evidence of patient’s mis-management with moral, financial and legal resultants. Clinical researches have recorded root resorption on all teeth; however, the lateral and central upper and lower incisors show the highest incidence and amount of resorption (Figure 1) (Levander and Malmgren, 1988; Remington et al. 1989; Kaley and Phillips, 1991; Beck and Harris, 1994; Alexander, 1996; Janson et al., 2000; Apa-jalahti and Peltola, 2007).

The extent of root resorption was occasionally quantita-tively and qualitaquantita-tively assessed using several method-ologies and imaging techniques. The relevant studies compared the root length of teeth before and after orthodontic treatment using lateral cephalometric radi-ographs (Copeland and Green, 1986; McFadden et al., 1989; Harris and Baker, 1990; Parker and Harris, 1998; Horiuchi et al., 1998), panoramic radiographs (Brin et al., 1991; Apajalahti and Peltola, 2007; Pandis et al., 2008), periapical radiographs (Levander and Malmgren, 1988; McFadden et al., 1989; Beck and Harris, 1994; Mirabella and Artun, 1995a,b; Smale et al., 2005) or periapical radi-ographs with the parallel long cone technique, with which any image distortion between initial and final radiographs is corrected using records based on the length of the crown of the tooth. This method, intro-duced by Linge and Linge (1983), has been used and modified by others, as well (Dermaut and De Munck, 1986; Mavragani et al., 2000; Mohandesan et al., 2007; van Loenen et al., 2007). The extent of root resorption of teeth was occasionally quantitatively and qualitatively

K

Keeyy wwoorrddss:: Root resorption, mechanical factors, orthodontic treatment

Hell Orthod Rev 2010;13:25-42.

Received: 02.11.2009 - Accepted: 14.01.2010 ‰ÔÓÙÈÒÓ Â›Ó·È ¤Ó· ·Úfi‚ÏÂÙÔ Ê·ÈÓfiÌÂÓÔ, ÔÏ˘·Ú·ÁÔÓÙÈ΋˜ ·ÈÙÈÔÏÔÁ›·˜. ª¤¯ÚÈ Û‹ÌÂÚ· Ê·›ÓÂÙ·È fiÙÈ ‰ÂÓ ˘¿Ú¯ÂÈ ÙÂÎÌËÚȈ̤ÓË ¿Ô„Ë Ë ÔÔ›· ÌÔÚ› Ó· Ô‰ËÁ‹ÛÂÈ ÛÂ Û˘ÁÎÂÎÚÈ̤Ó˜ ÛÙÚ·ÙËÁÈΤ˜, ÈηӤ˜ Ó· ÂÏ·¯ÈÛÙÔÔÈ‹ÛÔ˘Ó ‹ Ó· ·ÔÙÚ¤„Ô˘Ó ÙÔ Ê·ÈÓfiÌÂÓÔ Ù˘ ·ÔÚÚfiÊËÛ˘ ÙˆÓ ÚÈ˙ÒÓ. § §¤¤ÍÍÂÂÈȘ˜ ÎÎÏÏÂÂÈȉ‰ÈÈ¿¿:: ∞ÔÚÚfiÊËÛË ÚÈ˙ÒÓ, Ì˯·ÓÈÎÔ› ·Ú¿-ÁÔÓÙ˜, ÔÚıÔ‰ÔÓÙÈ΋ ıÂÚ·›· ∂ÏÏ √ÚıÔ‰ ∂Èı 2010;13:25-42. ¶·ÚÂÏ‹ÊıË: 02.11.2009 – ŒÁÈÓ ‰ÂÎÙ‹: 14.01.2010

Pandis Î·È Û˘Ó., 2008), ÂÚÈ·ÎÚÔÚÚÈ˙ÈÎÒÓ ·ÎÙÈÓÔÁÚ·-ÊÈÒÓ (Levander Î·È Malmgren, 1988; McFadden Î·È Û˘Ó., 1989; Beck Î·È Harris, 1994; Mirabella Î·È Artun, 1995a,b; Smale Î·È Û˘Ó., 2005) ‹ ÂÚÈ·ÎÚÔÚÚÈ˙ÈÎÒÓ ·ÎÙÈÓÔÁÚ·ÊÈÒÓ, Ì ÙËÓ ·Ú¿ÏÏËÏË Ù¯ÓÈ΋ Ì·ÎÚ¿˜ ‰¤ÛÌ˘ (long cone), ÛÙËÓ ÔÔ›·, οı ·Ú·ÌfiÚʈÛË ÂÈÎfiÓ·˜ ÌÂٷ͇ ÙˆÓ ·ÎÙÈÓÔÁÚ·ÊÈÒÓ ÚÈÓ Î·È ÌÂÙ¿ ÙË ıÂÚ·›·, ‰ÈÔÚıÒÓÂÙ·È ¯ÚËÛÈÌÔÔÈÒÓÙ·˜ ηٷÁڷʤ˜ ‚·ÛÈṲ̂Ó˜ ÛÙÔ Ì‹ÎÔ˜ Ù˘ ̇Ï˘ ÙÔ˘ ‰ÔÓÙÈÔ‡. ∏ ̤ıÔ-‰Ô˜ ·˘Ù‹ Ô˘ ÂÈÛ‹¯ıË ·fi ÙÔ˘˜ Linge Î·È Linge (1983), ¯ÚËÛÈÌÔÔÈ‹ıËΠ̠ÙÚÔÔÔÈ‹ÛÂȘ Î·È ·fi ¿ÏÏÔ˘˜ (Dermaut Î·È De Munck, 1986; Mavragani Î·È Û˘Ó., 2000; Mohandesan Î·È Û˘Ó., 2007; van Loenen Î·È Û˘Ó., 2007). ∆Ô Â‡ÚÔ˜ Ù˘ ·ÔÚÚfiÊËÛ˘ ÙˆÓ ÚÈ˙ÒÓ ÙˆÓ ‰ÔÓÙÈÒÓ ·ÍÈÔÏÔÁ‹ıËΠÔÈÔÙÈο ηٿ ηÈÚÔ‡˜ Ì ÔÙÈÎfi ÌÈÎÚÔÛÎfiÈÔ (Reitan, 1974; Winter Î·È Û˘Ó., 2009), Ì ËÏÂÎÙÚÔÓÈÎfi ÌÈÎÚÔÛÎfiÈÔ Û¿ÚˆÛ˘ (scanning electron microscopy) (SEM) (Kvam, 1972a,b), Î·È Ì ÙËÓ Ù¯ÓÈ΋ Ù˘ „ËÊȷ΋˜ ·Ê·ÈÚÂÙÈ΋˜ ·ÎÙÈÓÔÁÚ·Ê›·˜ (Gröndahl Î·È Gröndahl, 1983; Kravitz Î·È Û˘Ó., 1992; Reukers Î·È Û˘Ó., 1998; Heo Î·È Û˘Ó., 2001; Artun Î·È Û˘Ó., 2005; Smale Î·È Û˘Ó., 2005; van der Stelt, 2005), ηıÈÛÙÒÓÙ·˜ ¤ÙÛÈ ÛÙ·‰È·Î¿ ÈÔ ·ÛÊ·-Ï‹, ÙÔÓ ÔÛÔÙÈÎfi ÚÔÛ‰ÈÔÚÈÛÌfi ÙÔ˘ ‡ÚÔ˘˜ ÙˆÓ ·ÔÚ-ÚÔÊ‹ÛˆÓ. ∆· ÙÂÏÂ˘Ù·›· ¯ÚfiÓÈ·, ÌÂϤÙ˜ ‚·ÛÈṲ̂Ó˜ ÛÙËÓ ·ÍÔÓÈ΋ ÙÔÌÔÁÚ·Ê›· (Nance Î·È Û˘Ó., 2000; Weiland, 2003), ÙËÓ ·ÍÔÓÈ΋ ÙÔÌÔÁÚ·Ê›· ΈÓÈ΋˜ ‰¤ÛÌ˘ (Cevidanes Î·È Û˘Ó., 2006; Cohenca Î·È Û˘Ó., 2007; Patel Î·È Dawood, 2007; Lane Î·È Harrell, 2008;

assessed with optical microscopy (Reitan, 1974; Winter et al., 2009), scanning electron microscopy (SEM) (Kvam, 1972a,b), and digital subtraction radiography (Gröndahl abd Gröndahl, 1983; Kravitz et al., 1992; Reukers et al., 1998; Heo et al., 2001; Artun et al., 2005; Smale et al., 2005; van der Stelt, 2005; Ioannidou-Marathiotou et al., 2010), rendering in that way the quantitative determina-tion of the extend of resorpdetermina-tion gradually safer. During the last years, studies based on computed tomography (Nance et al., 2000; Weiland, 2003), on cone-beam com-puted tomography (Cevidanes et al., 2006; Cohenca et al., 2007; Patel and Dawood, 2007; Lane and Harrell, 2008; Quereshy et al., 2008; Patel et al., 2009), and on three-dimensional imaging techniques (Papadopoulos et al., 2002), in combination with scanning electron microscopy (Chan et al., 2004; Chan and Darendeliler, 2004) and microcomputed tomography (Harris et al., 2006; Foo et al., 2007; Barbagallo et al., 2008; Cheng et al., 2009), seem to open up new horizons for high relia-bility qualitative and quantitative assessment of the vol-ume and the size of root resorption of teeth.

The variety of methodologies makes the comparative assessment of findings difficult, as the extent of resorp-tion was determined sometimes in millimeters, some-times in percentages and somesome-times with arbitrary numerical scales. Thus, it has been found to range between 0.5-3 mm or to extend as far as the 1/4 or the 2/4 of the root length (Linge and Linge 1983; Linge and Linge 1991; Mirabella and Artun, 1995a; Brezniak and Wasserstein, 1993a; Brin et al., 2003; Artun et al., 2005). In a systematic study, it is also reported that 5% of the total orthodontic patients shows more than 5 mm reduc-tion of the root length (Taithongchai et al., 1996). In an effort to explain this phenomenon, several genetic factors have been implicated (Newman, 1975; Hartsfield et al., 2004), systemic aetiological factors, problems of endocrine glands like hypothyroidism or several hormon-al disorders, and nutrition deficient in chormon-alcium and vita-min D (Becks, 1939; Goldie and King, 1984; Malmgren et al., 1982; Linge and Linge 1983; Andreasen 1985; Sharp et al., 1987; Levander and Malmgren, 1988; Tronstad, 1988; McFadden et al., 1989; Goldin, 1989; Spurrier et al., 1990; Brin et al., 1991; Linge and Linge, 1991; Kaley and Phillips, 1991; Brezniak and Wasserstein, 1993 a,b; Kjaer, 1995; Mirabella and Artun, 1995b; Vlaskalic et al., 1998; Horiuchi et al., 1998; Kojima et al., 2002; Hartsfield et al., 2004; Smale et al., 2005; Abuabara, 2007). Biological factors have been also implicated, like sex (Kjaer, 1995; Spurrier et al., 1990; Baumrind et al., 1996),

∂∂ÈÈÎÎ.. 11.. ∂ÈÎfiÓ· 1. ¶·ÓÔÚ·ÌÈ΋ ·ÎÙÈÓÔÁÚ·Ê›· ·ÛıÂÓÔ‡˜ Ì ·ÔÚÚfi-ÊËÛË ÚÈ˙ÒÓ ÙˆÓ ¿Óˆ ÙÔ̤ˆÓ ÚÈÓ ÙË ‰ÈÂÓ¤ÚÁÂÈ· ÔÚıÔ‰ÔÓÙÈ΋˜ ıÂÚ·›·˜.

FFiigg.. 11.. Panoramic radiograph of patient with root resorption of the upper incisors before the application of orthodontic treatment.

Quereshy Î·È Û˘Ó., 2008; Patel Î·È Û˘Ó., 2009), Î·È ÙȘ ÙÚÈۉȿÛٷ٘ Ù¯ÓÈΤ˜ (Papadopoulos Î·È Û˘Ó., 2002), ÛÂ Û˘Ó‰˘·ÛÌfi Ì ËÏÂÎÙÚÔÓÈÎfi ÌÈÎÚÔÛÎfiÈÔ Û¿ÚˆÛ˘ (Chan Î·È Û˘Ó., 2004; Chan Î·È Darendeliler, 2004) Î·È ·ÎÙÈÓÔÁÚ·ÊÈ΋ ÌÈÎÚÔÙÔÌÔÁÚ·Ê›· (Harris Î·È Û˘Ó., 2006; Foo Î·È Û˘Ó., 2007; Barbagallo Î·È Û˘Ó., 2008; Cheng Î·È Û˘Ó., 2009), Ê·›ÓÂÙ·È Ó· ·ÓÔ›ÁÔ˘Ó Ó¤Â˜ ÚÔ-ÔÙÈΤ˜, ÁÈ· ˘„ËÏ‹˜ ·ÍÈÔÈÛÙ›·˜ ÔÈÔÙÈ΋ Î·È ÔÛÔÙÈ΋ ·ÍÈÔÏfiÁËÛË ÙÔ˘ fiÁÎÔ˘ Î·È ÙÔ˘ ÌÂÁ¤ıÔ˘˜ Ù˘ ·ÔÚÚfi-ÊËÛ˘ Ù˘ Ú›˙·˜ ÙˆÓ ‰ÔÓÙÈÒÓ. ∏ ‰È·ÊÔÚÂÙÈÎfiÙËÙ· ÙˆÓ ÌÂıÔ‰ÔÏÔÁÈÒÓ Î¿ÓÂÈ ‰‡ÛÎÔÏË ÙËÓ Û˘ÁÎÚÈÙÈ΋ ÌÂϤÙË ÙˆÓ Â˘ÚËÌ¿ÙˆÓ ÙˆÓ ‰È·ÊfiÚˆÓ ÂÚÁ·ÛÈÒÓ, ηıÒ˜ ÙÔ Ì¤ÁÂıÔ˜ Ù˘ ·ÔÚÚfiÊËÛ˘ ÚÔÛ-‰ÈÔÚ›ÛÙËΠ¿ÏÏÔÙ Û ¯ÈÏÈÔÛÙ¿, ¿ÏÏÔÙ Û ÂηÙÔÛÙÈ·›Â˜ ·Ó·ÏÔÁ›Â˜ Î·È ¿ÏÏÔÙ Ì ·˘ı·›ÚÂÙ˜ ·ÚÈıÌËÙÈΤ˜ ÎÏ›-̷Θ. ŒÙÛÈ ‚Ú¤ıËΠӷ Î˘Ì·›ÓÂÙ·È ÌÂٷ͇ 0,5-3 mm ‹ Ó· ÂÎÙ›ÓÂÙ·È ÛÙÔ 1/4 ‹ 2/4 ÙÔ˘ Ì‹ÎÔ˘˜ Ù˘ Ú›˙·˜ (Linge Î·È Linge 1983; Linge Î·È Linge 1991; Mirabella Î·È Artun, 1995a; Brezniak Î·È Wasserstein, 1993a; Brin Î·È Û˘Ó., 2003; Artun Î·È Û˘Ó., 2005). ™Â Ì›· Û˘ÛÙËÌ·-ÙÈ΋ ÌÂϤÙË ·Ó·Ê¤ÚÂÙ·È ·ÎfiÌË fiÙÈ 5% ÙÔ˘ Û˘ÓfiÏÔ˘ ÙˆÓ ÔÚıÔ‰ÔÓÙÈÎÒÓ ·ÛıÂÓÒÓ ·ÚÔ˘ÛÈ¿˙ÂÈ ÂÚÈÛÛfiÙÂÚÔ ·fi 5 mm ÂÏ¿ÙÙˆÛË ÙÔ˘ Ì‹ÎÔ˘˜ Ù˘ Ú›˙·˜ (Taithongchai Î·È Û˘Ó., 1996). ™ÙËÓ ÚÔÛ¿ıÂÈ· ÂÚÌËÓ›·˜ ÙÔ˘ Ê·ÈÓfiÌÂÓÔ˘ ·˘ÙÔ‡, ÂÓÔ¯ÔÔÈ‹ıËÎ·Ó ‰È¿ÊÔÚÔÈ ÁÂÓÂÙÈÎÔ› (Newman, 1975; Hartsfield Î·È Û˘Ó., 2004), Î·È Û˘ÛÙËÌ·ÙÈÎÔ› ·ÈÙÈÔÏÔÁÈ-ÎÔ› ·Ú¿ÁÔÓÙ˜, ÚÔ‚Ï‹Ì·Ù· ÂÓ‰ÔÎÚÈÓÒÓ ·‰¤ÓˆÓ fiˆ˜ Ô ˘Ôı˘ÚÂÔÂȉÈÛÌfi˜ ‹ ‰È¿ÊÔÚ˜ ÔÚÌÔÓÈΤ˜ ‰È·-Ù·Ú·¯¤˜, ηıÒ˜ Î·È Ë ‰È·ÙÚÔÊ‹ ·fi ¤ÏÏÂÈ„Ë ·Û‚ÂÛÙ›-Ô˘ Î·È ‚ÈÙ·Ì›Ó˘ D (Becks, 1939; Goldie Î·È King, 1984; Malmgren Î·È Û˘Ó., 1982; Linge Î·È Linge, 1983; Andreasen 1985; Sharp Î·È Û˘Ó., 1987; Levander Î·È Malmgren, 1988; Tronstad, 1988; McFadden Î·È Û˘Ó., 1989; Goldin, 1989; Spurrier Î·È Û˘Ó., 1990; Brin Î·È Û˘Ó., 1991; Linge Î·È Linge, 1991; Kaley Î·È Phillips, 1991; Brezniak Î·È Wasserstein, 1993 a,b; Kjaer, 1995; Mirabella Î·È Artun, 1995b; Vlaskalic Î·È Û˘Ó., 1998; Horiuchi Î·È Û˘Ó., 1998; Kojima Î·È Û˘Ó., 2002; Hartsfield Î·È Û˘Ó., 2004; Smale Î·È Û˘Ó., 2005; Abuabara, 2007). ∂›Û˘ ÂÓÔ¯ÔÔÈ‹ıËÎ·Ó Î·È ‚ÈÔÏÔÁÈÎÔ› ·Ú¿ÁÔÓÙ˜, fiˆ˜ ÙÔ Ê‡ÏÔ (Kjaer, 1995; Spurrier Î·È Û˘Ó., 1990; Baumrind Î·È Û˘Ó., 1996), Ë ËÏÈΛ· (McFadden Î·È Û˘Ó., 1989; Goldin, 1989; Hendrix Î·È Û˘Ó., 1994), ÙÔ ÛÙ¿‰ÈÔ ·Ó¿Ù˘Í˘ Ù˘ Ú›˙·˜ (Linge Î·È Linge, 1983, 1991), o Ù‡Ô˜ ÙÔ˘ ‰ÔÓÙÈÔ‡ (Sharpe Î·È Û˘Ó., 1987), Ë ÌÔÚÊÔÏÔÁ›· Ù˘ Ú›˙·˜ (Kjaer, 1995; Levander Î·È Û˘Ó., 1998b), Ë ·fiÎÏÈÛË Ù˘ Ú›˙·˜ (Levander Î·È Malmgren 1988; Mirabella Î·È Artun, 1995b), Ë ÂÁÁ‡ÙËÙ· Ù˘

age (McFadden et al., 1989; Goldin, 1989; Hendrix et al., 1994), the stage of root development (Linge and Linge, 1983, 1991), the type of tooth (Sharpe et al., 1987), root morphology (Kjaer, 1995; Levander et al., 1998b), root deviation (Levander and Malmgren 1988; Mirabella and Artun 1995b), proximity of root with cortical bone (Kaley and Phillips, 1991; Horiuchi et al., 1998), traumatized teeth (Linge and Linge 1983; Andreasen, 1985; Brin et al., 1991), endodontically treated teeth (Wickwire et al., 1974) – which have been not implicated by others (Mirabella and Artun, 1995a,b; Spurrier et al., 1990), denture anomalies, like ectopia (Kojima et al., 2002), ankylosis (Andersson et al., 1984), and multiple agenesis (Kjaer, 1995; Levander et al., 1998b) - which have been also not implicated by others (Lee et al., 1999), maxillo-facial anomalies like open bite (Harris and Butler, 1992), undesirable habits like nails biting (Odenrick and Brattstrom, 1985), allergy (Owman-Moll and Kurol, 2000), tongue and lip dysfunction (Linge and Linge, 1991), resorption existing before orthodontic treatment (Kaley and Phillips, 1991), medicines like aspirin (Kameyama et al., 1994), and periodontal diseases (Kinomoto et al., 2002).

Finally, an important degree of their involvement in root resorption has been attributed to several qualitative or/and quantitative characteristics of orthodontic treat-ment, like the duration of orthodontic treatment (Harry and Sims, 1982; Linge and Linge, 1983; Sharpe et al., 1987; Levander and Malmgren, 1988; Goldin, 1989; McFadden et al., 1989), the type of orthodontic appli-ances and the technique used (Linge and Linge, 1983; Malmgren and Omblus, 1985; Beck and Harris, 1994), the type of tooth movement like intrusion (Harry and Sims, 1982; Dermaut and De Munck, 1986; Parker and Harris, 1998) or torque (Kaley and Phillips, 1991; Parker and Har-ris, 1998), the magnitude of the applied forces (Hollen-der et al., 1980; Linge and Linge, 1983; Sharpe et al., 1987; Levander et al., 1994), and the use of elastics com-bined with rectangular wires (Linge and Linge, 1983, 1991; Mirabella and Artun, 1995b).

According to the above mentioned issues, it is obvious that orthodontic treatment plays an important role in the etiology of root resorption of the teeth undergoing movements.

With this review based on the published data, the temporary knowledge and the new developments con-cerning orthodontic movement, an attempt is made to discuss and critical analyze the mechanical factors asso-ciated with orthodontic treatment and implicated in the formation of root resorption.

Ú›˙·˜ Ì ÙÔ ÊÏÔÈ҉˜ ¤Ù·ÏÔ (Kaley Î·È Phillips, 1991; Horiuchi Î·È Û˘Ó., 1998) Ù· ÙÚ·˘Ì·ÙÈṲ̂ӷ ‰fiÓÙÈ· (Linge Î·È Linge, 1983; Andreasen, 1985; Brin Î·È Û˘Ó., 1991), Ù· ÂÓ‰Ô‰ÔÓÙÈο ıÂÚ·Â˘Ì¤Ó· ‰fiÓÙÈ· (Wickwire Î·È Û˘Ó., 1974) Ù· ÔÔ›· fï˜ ·ÂÓÔ¯ÔÔÈ-‹ıËÎ·Ó ·fi ¿ÏÏÔ˘˜ Û˘ÁÁÚ·Ê›˜ (Mirabella Î·È Artun, 1995a,b; Spurrier Î·È Û˘Ó., 1990), ÔÈ ·ÓˆÌ·Ï›Â˜ Ù˘ Ô‰ÔÓÙÔÊ˘›·˜, fiˆ˜ Ë ÂÎÙÔ›· (Kojima Î·È Û˘Ó., 2002) Ë ·Á·ψÛË (Andersson Î·È Û˘Ó., 1984) Î·È Ë ÔÏÏ·-Ï‹ ·ÁÂÓÂÛ›· (Kjaer, 1995; Levander Î·È Û˘Ó., 1998b), ÔÈ Ôԛ˜ Â›Û˘ ·ÂÓÔ¯ÔÔÈ‹ıËÎ·Ó ·fi ¿ÏÏÔ˘˜ Û˘Á-ÁÚ·Ê›˜ (Lee Î·È Û˘Ó., 1999), ÔÈ ÁÓ·ıÔÚÔÛˆÈΤ˜ ·ÓˆÌ·Ï›Â˜ fiˆ˜ Ë ·ÓˆÁ̤ÓË ‰‹ÍË (Harris Î·È Butler, 1992), ÔÈ ·ÓÂÈı‡ÌËÙ˜ ¤ÍÂȘ fiˆ˜ Ë ÔÓ˘¯ÔÊ·Á›· (Odenrick Î·È Brattstrom, 1985), Ë ·ÏÏÂÚÁ›· (Owman-Moll Î·È Kurol, 2000), Ë ‰˘ÛÏÂÈÙÔ˘ÚÁ›· Ù˘ ÁÏÒÛÛ·˜ Î·È ÙˆÓ ¯ÂÈϤˆÓ (Linge Î·È Linge, 1991), Ë ÚÔ¸¿Ú-¯Ô˘Û· ·ÔÚÚfiÊËÛË ÚÈÓ ·fi ÙËÓ ÔÚıÔ‰ÔÓÙÈ΋ ıÂÚ·-›· (Kaley Î·È Phillips, 1991), Ê¿Ú̷η fiˆ˜ Ë ·ÛÈ-Ú›ÓË (Kameyama Î·È Û˘Ó., 1994), ηıÒ˜ Î·È ÔÈ ÓfiÛÔÈ ÙÔ˘ ÂÚÈÔ‰ÔÓÙ›Ô˘ (Kinomoto Î·È Û˘Ó., 2002). ∆¤ÏÔ˜, ÛËÌ·ÓÙÈÎfi˜ ‚·ıÌfi˜ Û˘ÌÌÂÙÔ¯‹˜ ÛÙȘ ·ÔÚÚÔ-Ê‹ÛÂȘ ÙˆÓ ÚÈ˙ÒÓ ·Ô‰fiıËÎÂ Î·È ÛÙ· ‰È¿ÊÔÚ· ÔÈÔÙÈ-ο ‹/Î·È ÔÛÔÙÈÔÈÔÙÈ-ο ¯·Ú·ÎÙËÚÈÛÙÈÔÈÔÙÈ-ο Ù˘ ÔÚıÔ‰ÔÓÙÈ΋˜ ıÂÚ·›·˜, fiˆ˜ Ë ‰È¿ÚÎÂÈ· Ù˘ ÔÚıÔ‰ÔÓÙÈ΋˜ ıÂÚ·-›·˜ (Harry Î·È Sims, 1982; Linge Î·È Linge, 1983; Sharpe Î·È Û˘Ó., 1987; Levander Î·È Malmgren, 1988; Goldin, 1989; McFadden Î·È Û˘Ó., 1989), ÙÔ Â›‰Ô˜ ÙˆÓ ÔÚıÔ‰ÔÓÙÈÎÒÓ Û˘Û΢ÒÓ Î·È Ë Ù¯ÓÈ΋ Ô˘ ¯ÚËÛÈÌÔ-ÔÈÂ›Ù·È (Linge Î·È Linge, 1983; Malmgren Î·È Omblus, 1985; Beck Î·È Harris, 1994), Ô Ù‡Ô˜ Ù˘ ÌÂٷΛÓËÛ˘ ÙÔ˘ ‰ÔÓÙÈÔ‡ fiˆ˜ Ë ÂÌ‚‡ıÈÛË (Harry Î·È Sims, 1982; Dermaut Î·È De Munck, 1986; Parker Î·È Harris, 1998) Î·È Ë ÚÔ‹ (Kaley Î·È Phillips, 1991; Parker Î·È Harris, 1998), Ë ¤ÓÙ·ÛË ÙˆÓ ‰˘Ó¿ÌÂˆÓ Ô˘ ·ÛÎÔ‡ÓÙ·È (Hollender Î·È Û˘Ó., 1980; Linge Î·È Linge, 1983; Sharpe Î·È Û˘Ó., 1987; Levander Î·È Û˘Ó., 1994), ηıÒ˜ Î·È Ë ¯Ú‹ÛË ÂÏ·ÛÙÈÎÒÓ ‰˘Ó¿ÌÂˆÓ ÛÂ Û˘Ó‰˘·-ÛÌfi Ì ÔÚıÔÁÒÓÈ· Û‡ÚÌ·Ù· (Linge Î·È Linge, 1983, 1991; Mirabella Î·È Artun, 1995b). ∞fi Ù· ·Ú·¿Óˆ ηı›ÛÙ·Ù·È ÚÔÊ·Ó¤˜ fiÙÈ Ë ÔÚıÔ‰Ô-ÓÙÈ΋ ıÂÚ·›· Û˘ÌÌÂÙ¤¯ÂÈ Û ÌÂÁ¿ÏÔ ‚·ıÌfi ÛÙËÓ ·ÈÙÈÔÏÔÁ›· Ù˘ ·ÔÚÚfiÊËÛ˘ ÙˆÓ ÚÈ˙ÒÓ ÙˆÓ ‰ÔÓÙÈÒÓ Ô˘ ˘Ê›ÛÙ·ÓÙ·È ÌÂÙ·ÎÈÓ‹ÛÂȘ. ªÂ ÙËÓ ·ÚÔ‡Û· ·Ó·ÛÎfiËÛË ÂȯÂÈÚÂ›Ù·È Ì¤Û· ·fi Ù· ÎÏ·ÛÛÈο ‰Â‰Ô̤ӷ, ÙË Û‡Á¯ÚÔÓË ÁÓÒÛË Î·È ÙȘ Ӥ˜ ÂÍÂÏ›ÍÂȘ ÛÙÔ ı¤Ì· Ù˘ ÔÚıÔ‰ÔÓÙÈ΋˜ ÌÂٷΛÓËÛ˘, Ó· Á›ÓÂÈ ÌÈ· ÚÔÛ¿ıÂÈ· ÂÈηÈÚÔÔ›ËÛ˘, Û˘˙‹ÙËÛ˘ Î·È ÎÚÈÙÈ΋˜ ·Ó¿Ï˘Û˘ ÙˆÓ Ì˯·ÓÈÎÒÓ ·Ú·ÁfiÓÙˆÓ Ô˘ Û¯ÂÙ›˙ÔÓÙ·È Ì ÙËÓ ÔÚıÔ‰ÔÓÙÈ΋ ıÂÚ·›· Î·È ÂÓÔ¯Ô-M

MEECCHHAANNIICCAALL FFAACCTTOORRSS OOFF RROOOOTT RREESSOORRPPTTIIOONN T

Tyyppee ((ddiirreeccttiioonn)) ooff oorrtthhooddoonnttiicc mmoovveemmeenntt

Type or direction of orthodontic movement seems to have different results in the degree of root resorption of teeth.

Regarding the bodily tooth movement, it was found out that the extent of root resorption is limited, and this is due to the fact that during the bodily movement of the tooth, the applied forces are distributed through the whole length of its root, the stress (force per surface unit) is reduced, and thus, the harmful effect of the applied forces at the apex is reduced (Reitan, 1985). However, it has been reported that the distance covered by the tooth on the horizontal plane, especially in pre-molar extraction cases, is associated with the amount of resorption (Sharpe et al., 1987; Kaley and Phillips, 1991). Non visible root resorptions during bodily movement were discovered by Parker and Harris (1998) in a study with 110 adult patients with similar Class I bimaxillary malocclusions. Thus, it seems that the forces applied dur-ing bodily movement of teeth induce root resorptions, however, these are of limited extent and they are relat-ed to the distance coverrelat-ed by the teeth.

The studies focused on the effect of intrusion on root resorption resulted in conflicted resu;ts. According to some of them, it seems that there is no significant corre-lation between intrusion and root resorption (McFadden et al., 1989; Mirabella and Artun, 1995b), while, accord-ing to others, forces generataccord-ing intrusion of the teeth are of the most aggressive (DeShields, 1969; Dermaut and De Munck, 1986; Costopoulos and Nanda, 1996; Parker and Harris, 1998; Vlaskalic et al., 1998; Gioka and Eli-ades, 2003; Han et al., 2005; Zafeiriadis and Lambrianidis, 2008). These forces are focused on the apex and because of the profound stress applied, they induce an ischemic necrosis at the periodontal ligament and activation on cellular level of the mechanisms causing root resorption. Especially interesting is a recent study in which the authors recorded the harmful effect of intrusion forces at the apex of the teeth (Chiqueto et al., 2008). This study was based on a homogeneous sample of patients with profound deep bite and a control group with normal deep bite treated without teeth extractions. Deep bite was treated in the first group with the use of intrusion arches with acute reverse curve of Spee, whereas the control group was treated without the application of intrusion forces. The results of the research confirm the formation of resorptions in the group where intrusion

ÔÈÔ‡ÓÙ·È ÁÈ· ÙË ‰ËÌÈÔ˘ÚÁ›· ·ÔÚÚÔÊ‹ÛÂˆÓ ÙˆÓ ÚÈ˙ÒÓ ÙˆÓ ‰ÔÓÙÈÒÓ. ª ª∏∏ÃÃ∞∞¡¡ππ∫∫√√π𠶶∞∞ƒƒ∞∞°°√√¡¡∆∆∂∂™™ ∞∞¶¶√√ƒƒƒƒ√√ºº∏∏™™∏∏™™ ƒƒππ∑∑øø¡¡ ∆ ∆‡‡ÔÔ˜˜ ((Îη·ÙÙ‡‡ıı˘˘ÓÓÛÛËË)) ÙÙˢ˜ ÔÔÚÚııÔÔ‰‰ÔÔÓÓÙÙÈÈÎ΋‹˜˜ ÌÌÂÂÙÙ··ÎΛ›ÓÓËËÛÛˢ˜ √ Ù‡Ô˜ ‹ Ë Î·Ù‡ı˘ÓÛË Ù˘ ÔÚıÔ‰ÔÓÙÈ΋˜ ÌÂٷΛÓË-Û˘ Ê·›ÓÂÙ·È Ó· ¤¯ÂÈ ‰È·ÊÔÚÂÙÈο ·ÔÙÂϤÛÌ·Ù· ÛÙÔÓ ‚·ıÌfi Ù˘ ·ÔÚÚfiÊËÛ˘ ÙˆÓ ÚÈ˙ÒÓ ÙˆÓ ‰ÔÓÙÈÒÓ Ô˘ ÙȘ ˘Ê›ÛÙ·ÓÙ·È. ŸÛÔÓ ·ÊÔÚ¿ ÙËÓ ÌÂٷΛÓËÛË ÙˆÓ ‰ÔÓÙÈÒÓ Ì ·Ú¿Ï-ÏËÏË ÌÂÙ·ÙfiÈÛË (bodily movement), ‰È·Ù˘ÒıËΠfiÙÈ Ë ¤ÎÙ·ÛË Ù˘ ·ÔÚÚfiÊËÛ˘ Ù˘ Ú›˙·˜ Â›Ó·È ÂÚÈÔÚÈṲ̂-ÓË Î·È ÔÊ›ÏÂÙ·È ÛÙÔ ÁÂÁÔÓfi˜ fiÙÈ Î·Ù¿ ÙËÓ ·Ú¿ÏÏËÏË ÌÂٷΛÓËÛË ÙÔ˘ ‰ÔÓÙÈÔ‡, ÔÈ ·ÛÎÔ‡ÌÂÓ˜ ‰˘Ó¿ÌÂȘ ηٷӤÌÔÓÙ·È Û fiÏÔ ÙÔ Ì‹ÎÔ˜ Ù˘ Ú›˙·˜ ÙÔ˘, Ë ›ÂÛË (‰‡Ó·ÌË ·Ó¿ ÌÔÓ¿‰· ÂÈÊ·Ó›·˜) Â›Ó·È ÌÂȈ̤ÓË, Î·È Î·Ù¿ Û˘Ó¤ÂÈ· Â›Ó·È ÂÚÈÔÚÈṲ̂ÓË Ë ÂÈ‚Ï·‚‹˜ ‰Ú¿ÛË ÙˆÓ ·ÛÎÔ‡ÌÂÓˆÓ ‰˘Ó¿ÌÂˆÓ ÛÙÔ ·ÎÚÔÚÚ›˙ÈÔ (Reitan, 1985). øÛÙfiÛÔ ¤¯ÂÈ ·Ó·ÊÂÚı›, fiÙÈ Ë ·fiÛÙ·ÛË Ô˘ ‰È·Ó‡ÂÈ ÙÔ ‰fiÓÙÈ Î·Ù¿ ÙÔ ÔÚÈ˙fiÓÙÈÔ Â›‰Ô, ȉȷ›ÙÂÚ· Û ÂÚÈÙÒÛÂȘ Ì ÂÍ·ÁˆÁ¤˜ ÚÔÁÔÌÊ›ˆÓ, ¤¯ÂÈ Û¯¤ÛË Ì ÙÔ ‚·ıÌfi ·ÔÚÚfiÊËÛ˘ (Sharpe Î·È Û˘Ó., 1987; Kaley Î·È Phillips, 1991). ∞ÔÚÚÔÊ‹ÛÂȘ ÚÈ˙ÒÓ ÌË ‰È·-ÎÚÈÙ¤˜ ηٿ ÙËÓ ·Ú¿ÏÏËÏË ÌÂٷΛÓËÛË, ‰È·›ÛÙˆÛ·Ó ÔÈ Parker Î·È Harris (1998) Û ̛· ÌÂϤÙË Ì 110 ÂÓ‹ÏÈ-Θ ·ÛıÂÓ›˜ Ô˘ ·ÚÔ˘Û›·˙·Ó ·ÚfiÌÔȘ Û˘ÁÎÏÂÈÛÈ·-Τ˜ ·ÓˆÌ·Ï›Â˜ ∆¿Í˘ π ηٿ Angle Î·È ·ÌÊÈÚÔ‚ÔÏ‹ ÙˆÓ ÁÓ¿ıˆÓ. º·›ÓÂÙ·È Û˘ÓÂÒ˜ fiÙÈ ÔÈ ‰˘Ó¿ÌÂȘ Ô˘ ·ÛÎÔ‡ÓÙ·È Î·Ù¿ ÙËÓ ·Ú¿ÏÏËÏË ÌÂٷΛÓËÛË ‰ÔÓÙÈÒÓ ÚÔηÏÔ‡Ó ·ÔÚÚÔÊ‹ÛÂȘ ÚÈ˙ÒÓ, ˆÛÙfiÛÔ ·˘Ù¤˜ Â›Ó·È ÂÚÈÔÚÈṲ̂Ó˘ ¤ÎÙ·Û˘ Î·È Â›Ó·È Û˘Ó¿ÚÙËÛË Ù˘ ·fi-ÛÙ·Û˘ Ô˘ ı· ‰È·Ó‡ÛÔ˘Ó Ù· ‰fiÓÙÈ·. √È ÌÂϤÙ˜ Ô˘ ÂÛÙÈ¿ÛÙËÎ·Ó ÛÙËÓ Â›‰Ú·ÛË Ù˘ ÌÂٷΛ-ÓËÛ˘ ÂÌ‚‡ıÈÛ˘ (intrusion) ÛÙËÓ ·ÔÚÚfiÊËÛË ÙˆÓ ÚÈ˙ÒÓ ÙˆÓ ‰ÔÓÙÈÒÓ Î·Ù¤ÏËÍ·Ó Û ·ÏÏËÏÔÛ˘ÁÎÚÔ˘fiÌÂ-Ó˜ ·fi„ÂȘ. ™‡Ìʈӷ Ì οÔȘ ·fi ·˘Ù¤˜ Ê·›ÓÂÙ·È fiÙÈ ‰ÂÓ ˘¿Ú¯ÂÈ ÛËÌ·ÓÙÈ΋ Û¯¤ÛË ÌÂٷ͇ Ù˘ ÌÂٷΛÓË-Û˘ Ù˘ ÂÌ‚‡ıÈÌÂٷΛÓË-Û˘ Î·È Ù˘ ·ÔÚÚfiÊËÌÂٷΛÓË-Û˘ ÙˆÓ ÚÈ˙ÒÓ (McFadden Î·È Û˘Ó., 1989; Mirabella Î·È Artun, 1995b), ÂÓÒ Û‡Ìʈӷ Ì ¿ÏϘ fiÙÈ ÔÈ ‰˘Ó¿ÌÂȘ Ô˘ ÚÔηÏÔ‡Ó ÂÌ‚‡ıÈÛË ÙˆÓ ‰ÔÓÙÈÒÓ Â›Ó·È ·fi ÙȘ ϤÔÓ ÂÈıÂÙÈΤ˜ (DeShields, 1969; Dermaut Î·È De Munck, 1986; Costopoulos Î·È Nanda, 1996; Parker Î·È Harris, 1998; Vlaskalic Î·È Û˘Ó., 1998; Gioka Î·È Eliades, 2003; Han Î·È Û˘Ó., 2005; Zafeiriadis Î·È Lambrianidis, 2008). √È ‰˘Ó¿ÌÂȘ ·˘Ù¤˜ ÂÛÙÈ¿˙ÔÓÙ·È ÛÙÔ ·ÎÚÔÚÚ›˙ÈÔ Î·È ÏfiÁˆ Ù˘ ¤ÓÙÔÓ˘ ›ÂÛ˘ Ô˘ ·ÛΛٷÈ, ‰ËÌÈÔ˘Ú-ÁÔ‡Ó ÈÛ¯·ÈÌÈ΋ Ó¤ÎÚˆÛË ÛÙÔÓ ÂÚÈÔ‰ÔÓÙÈÎfi Û‡Ó‰ÂÛÌÔ

mechanics were applied.

The forces generating extrusion of teeth and their asso-ciation with root resorption were subjected to limited research work (Mirabella and Artun, 1995b; Parker and Harris, 1998), possibly because extrusion forces do not charge teeth at the apex and thus, they do not consti-tute a resorption inducing factor. However, an animal study demonstrated resorption at the apical third of the root after extrusion of teeth (Weekes and Wong, 1995). In addition, in an interesting comparative study, after the application of intrusion and extrusion forces on the pre-molars of the same patient, it was found that intrusion forces cause 4 times more resorption than extrusion forces (Han et al., 2005). It seems therefore that extru-sion can cause root resorptions in a limited extent, how-ever, more studies are necessary in order to draw safer conclusions.

With regard to torque forces, root resorption has been observed on the lingual and labial surfaces following their application for root or crown toque (Ten Hoeve and Mulie, 1976; Williams, 1984; Reitan, 1985; Goldin, 1989). According to a subsequent study, it seems that lingual root torque combined with intrusion, are the most pre-dictable factors inducing root resorption (Parker and Har-ris, 1998). In a recent study, resorption percentage was assessed for Tip-Edge technique before and after torque application (van Loenen et al., 2007). Findings showed similar percentages of root resorption on the teeth stud-ied in both cases. As a result, the authors concluded that torque movement constitutes an aggravating and not an emitting factor of root resorption, attributing the induc-tion of this phenomenon primarily to genetic factors. Regarding the forces generating teeth rotation, they rotate the teeth around their axis inducing minimal stress on their roots surface and consequently limited root resorption, as it was observed in animal studies (Brain, 1969; Redlich et al., 1996). However, in a relative-ly recent clinical study, cenotopia were observed on the surfaces of all premolars undergoing rotation, while at the same time these resorption surfaces were located on the middle third of the root, namely, on surfaces where root morphology has the most profound projection (Jimenez-Pellegrin and Arana-Chavez, 2004).

Finally, jiggling of teeth was implicated as one more mechanical factor inducing root resorption. Jiggling movements cause occlusal trauma that can activate the mechanism initiating root resorption (Linge and Linge 1983, 1991; Levander et al., 1998a; Killiany, 1999; Brez-niak and Wasserstein, 1993b; BrezBrez-niak and Wasserstein, 2002b). Moreover, it was found that root resorption of

Î·È ÂÓÂÚÁÔÔ›ËÛË Û ΢ÙÙ·ÚÈÎfi Â›Â‰Ô ÙˆÓ ÂÎÏ˘ÙÈÎÒÓ Ì˯·ÓÈÛÌÒÓ ·ÔÚÚfiÊËÛ˘ ÙˆÓ ÚÈ˙ÒÓ. π‰È·›ÙÂÚ· ÂӉȷ-ʤÚÔ˘Û· Â›Ó·È ÌÈ· ÚfiÛÊ·ÙË ÌÂϤÙË ÛÙËÓ ÔÔ›· ÔÈ Û˘ÁÁÚ·Ê›˜ ηٷÁÚ¿ÊÔ˘Ó ÙË ‚Ï·‚ÂÚ‹ ‰Ú¿ÛË ÙˆÓ ‰˘Ó¿ÌÂˆÓ ÂÌ‚‡ıÈÛ˘ ÛÙÔ ·ÎÚÔÚÚ›˙ÈÔ ÙˆÓ ‰ÔÓÙÈÒÓ (Chiqueto Î·È Û˘Ó., 2008). ∏ ÌÂϤÙË ·˘Ù‹ ‚·Û›ÛÙËΠ۠ÔÌÔÈÔÁÂÓ¤˜ ‰Â›ÁÌ· ·ÛıÂÓÒÓ Ì ¤ÓÙÔÓË ˘ÂÚÛ‡-ÁÎÏÂÈÛË Î·È ¤Ó· ‰Â›ÁÌ· ÂϤÁ¯Ô˘ ÌÂ Ê˘ÛÈÔÏÔÁÈ΋ ηٷ-ÎfiÚ˘ÊË ÂÈÎ¿Ï˘„Ë, Ù· ÔÔ›· ıÂÚ·‡ÙËÎ·Ó ¯ˆÚ›˜ ÂÍ·ÁˆÁ¤˜ ‰ÔÓÙÈÒÓ. ∏ ˘ÂÚÛ‡ÁÎÏÂÈÛË ÛÙË ÚÒÙË ÔÌ¿‰· ıÂÚ·‡ÙËΠ̠ÙfiÍ· ÂÌ‚‡ıÈÛ˘ Ì ¤ÓÙÔÓË ·ÓÙ›-ÛÙÚÔÊË Î·Ì‡ÏË ÙÔ˘ Spee, ÂÓÒ Ë ÔÌ¿‰· ÂϤÁ¯Ô˘ ıÂÚ·‡ÙËΠ¯ˆÚ›˜ ÙËÓ ÂÊ·ÚÌÔÁ‹ ‰˘Ó¿ÌÂˆÓ ÂÌ‚‡ıÈ-Û˘. ∆· ·ÔÙÂϤÛÌ·Ù· Ù˘ ¤Ú¢ӷ˜ ÂȂ‚·ÈÒÓÔ˘Ó ÙËÓ ‰ËÌÈÔ˘ÚÁ›· ·ÔÚÚÔÊ‹ÛÂˆÓ ÛÙËÓ ÔÌ¿‰· fiÔ˘ ÂÊ·Ú-ÌfiÛÙËÎ·Ó ÔÈ Ì˯·ÓÈÛÌÔ› ÂÌ‚‡ıÈÛ˘. √È ‰˘Ó¿ÌÂȘ Ô˘ ÚÔηÏÔ‡Ó ˘ÂÚ¤ÎÊ˘ÛË (extrusion) ÙˆÓ ‰ÔÓÙÈÒÓ Î·È ÔÈ Û¯¤ÛÂȘ ÙÔ˘˜ Ì ÙËÓ ·ÔÚÚfiÊËÛË ÙˆÓ ÚÈ˙ÒÓ ·ÔÙ¤ÏÂÛ·Ó ·ÓÙÈΛÌÂÓÔ ÂÚÈÔÚÈÛÌ¤ÓˆÓ ÂÚ¢ÓÒÓ (Mirabella Î·È Artun, 1995b; Parker Î·È Harris, 1998), ›Ûˆ˜ ÂÍ’ ·ÈÙ›·˜ ÙÔ˘ ÁÂÁÔÓfiÙÔ˜ fiÙÈ ÔÈ ‰˘Ó¿ÌÂȘ ˘ÂÚ¤ÎÊ˘Û˘ ‰ÂÓ ÂÈÊÔÚÙ›˙Ô˘Ó Ù· ‰fiÓÙÈ· ÛÙÔ ·ÎÚÔÚÚ›˙ÈÔ Î·È Û˘ÓÂÒ˜ ‰ÂÓ Û˘ÓÈÛÙÔ‡Ó ·Ú¿ÁÔÓÙ· ÚfiÎÏËÛ˘ ·ÔÚÚÔÊ‹ÛˆÓ. øÛÙfiÛÔ, ÌÈ· ÌÂϤÙË Û ÂÈÚ·Ì·Ùfi˙ˆ· ·¤‰ÂÈÍ fiÙÈ ÌÂÙ¿ ÙËÓ ÌÂٷΛÓËÛË ˘Â-Ú¤ÎÊ˘Û˘ ‰ÔÓÙÈÒÓ ‰È·ÈÛÙÒıËΠ·ÔÚÚfiÊËÛË ÛÙÔ ·˘¯ÂÓÈÎfi ÙÚÈÙËÌfiÚÈÔ Ù˘ Ú›˙·˜ ÙÔ˘˜ (Weekes Î·È Wong, 1995). ∂›Û˘, Û ÌÈ· ÂӉȷʤÚÔ˘Û· Û˘ÁÎÚÈÙÈ΋ ÌÂϤÙË ÂÊ·ÚÌÔÁ‹˜ ‰˘Ó¿ÌÂˆÓ ÂÌ‚‡ıÈÛ˘ Î·È ˘ÂÚ¤Î-Ê˘Û˘ Û ÚÔÁÔÌÊ›Ô˘˜ ÙÔ˘ ›‰ÈÔ˘ ÙÔ˘ ·ÛıÂÓ‹ ‚Ú¤ıËΠfiÙÈ ÔÈ ‰˘Ó¿ÌÂȘ ÂÌ‚‡ıÈÛ˘ ÚÔηÏÔ‡Ó 4 ÊÔÚ¤˜ ÂÚÈÛ-ÛfiÙÂÚË ·ÔÚÚfiÊËÛË ·fi fiÙÈ ÔÈ ‰˘Ó¿ÌÂȘ ˘ÂÚ¤ÎÊ˘-Û˘ (Han Î·È Û˘Ó., 2005). º·›ÓÂÙ·È Û˘ÓÂÒ˜ fiÙÈ Î·È Ë ˘ÂÚ¤ÎÊ˘ÛË Â›Ó·È ÌÈ· ΛÓËÛË Ô˘ ÌÔÚ› Ó· ÚÔηϤ-ÛÂÈ ·ÔÚÚÔÊ‹ÚÔηϤ-ÛÂȘ ÙˆÓ ÚÈ˙ÒÓ ÙˆÓ ‰ÔÓÙÈÒÓ Û ÂÚÈÔÚÈ-Ṳ̂ÓË ¤ÎÙ·ÛË, ˆÛÙfiÛÔ ÁÈ· ÙËÓ ÂÍ·ÁˆÁ‹ ·ÛÊ·ÏÒÓ Û˘ÌÂÚ·ÛÌ¿ÙˆÓ Â›Ó·È ··Ú·›ÙËÙ˜ ÂÈϤÔÓ ÌÂϤÙ˜. ŸÛÔ ·ÊÔÚ¿ ÙȘ ‰˘Ó¿ÌÂȘ ÛÙÚ¤„˘ (torque) ¤¯ÂÈ ·Ú·-ÙËÚËı› ·ÔÚÚfiÊËÛË ÙˆÓ ÚÈ˙ÒÓ ÙfiÛÔ Î·Ù¿ ÙËÓ ÂÊ·Ú-ÌÔÁ‹ ÙÔ˘˜ ÁÈ· ÙË ÛÙÚ¤„Ë Ù˘ Ú›˙·˜ ‹ Ù˘ ̇Ï˘ ÙˆÓ ‰ÔÓÙÈÒÓ ÙfiÛÔ ÁψÛÛÈο fiÛÔ Î·È ¯ÂÈÏÈο (Ten Hoeve Î·È Mulie, 1976; Williams, 1984; Reitan, 1985; Goldin, 1989). ™‡Ìʈӷ Ì ÌÈ· ÌÂÙ·ÁÂÓ¤ÛÙÂÚË ÌÂϤÙË Ê·›ÓÂÙ·È fiÙÈ Ë ÛÙÚ¤„Ë ÙˆÓ ÚÈ˙ÒÓ ÙˆÓ ‰ÔÓÙÈÒÓ ÁψÛÛÈο (lingual root torque) ÛÂ Û˘Ó‰˘·ÛÌfi Ì ÙËÓ Î›ÓËÛË Ù˘ ÂÌ‚‡ıÈÛ˘, ·ÔÙÂÏÔ‡Ó ÙÔ˘˜ ÈÔ ÚԂϤ„ÈÌÔ˘˜ ·Ú¿-ÁÔÓÙ˜ ‰ËÌÈÔ˘ÚÁ›·˜ ·ÔÚÚfiÊËÛ˘ ÚÈ˙ÒÓ (Parker Î·È Harris, 1998). ™Â ÌÈ· ÈÔ ÚfiÛÊ·ÙË ÌÂϤÙË, ·ÍÈÔÏÔÁ‹-ıËΠÙÔ ÔÛÔÛÙfi ·ÔÚÚfiÊËÛ˘ Ì ÙËÓ Ù¯ÓÈ΋ ∆ip-Edge ÚÈÓ Î·È ÌÂÙ¿ ÙË ‰ÈÂÓ¤ÚÁÂÈ· Ù˘ ÌÂٷΛÓËÛ˘

ÛÙÚ¤-upper molars was similar in cases where the ÛÙÚ¤-upper molars were used for the application of intermaxillary elastics during the night, as well as when they were used for extraoral traction, or for the application of Goshgar-ian transpalatal arch (Alwali et al., 2000). Finally, jiggling movements and occlusal traumas leading to root resorp-tion can be induced even by retenresorp-tion appliances placed after the end of orthodontic treatment (Copeland and Green, 1986).

R

Reemmoovvaabbllee aanndd ffiixxeedd oorrtthhooddoonnttiicc aapppplliiaanncceess

The use of fixed orthodontic appliances and their effect on the mechanism of inducing root resorption was for many years the subject of investigation in a plethora of studies (Ketcham, 1927; Massler and Malone, 1954; Kvam, 1972a,b; Newman, 1975; Malmgren et al., 1982; Copeland and Green, 1986; Beck and Harris, 1994; Baumrind et al., 1996; and many others). However, the studies dealing with the comparison between remov-able and fixed orthodontic appliances and their effect on root resorption are limited. In such a study, it was observed that the application of fixed appliances was more harmful for the apex of the teeth (Linge and Linge, 1983). Similar results have been drawn by anoth-er comparative study in patients 10 years aftanoth-er ortho-dontic treatment, in which root resorption was observed in the patients where fixed appliances were placed (Kennedy et al., 1983). Without doubt, the com-parison between removable and fixed appliances impli-cates the latter. However, removable appliances cannot be excluded as a possible etiological factor of root resorption, as they are implicated for the induction of occlusal traumas and jiggling movements, causing this way a harmful effect on the apex of the teeth (Linge and Linge, 1983; Odenrick and Brattstrom, 1985; Copeland and Green, 1986).

O

Orrtthhooddoonnttiicc tteecchhnniiqquueess

The significant number of techniques used today does not make feasible a comparative evaluation among them. The existing data derive sometimes from the assessment of only one technique, sometimes from the comparison between 2 techniques, while one paper refers to the comparative study among 3 techniques. With regard to the Edgewise technique, Kaley and Phillips (1991) found in a sample of 200 patients that 3% these patients presented significant resorption (greater than the _ of the root) of the root of the two upper

cen-„˘ (van Loenen Î·È Û˘Ó., 2007). ∆· Â˘Ú‹Ì·Ù· ¤‰ÂÈÍ·Ó ·ÚfiÌÔÈ· ÔÛÔÛÙ¿ ·ÔÚÚfiÊËÛ˘ ÚÈ˙ÒÓ ÛÙ· ˘fi Âͤ-Ù·ÛË ‰fiÓÙÈ· Î·È ÛÙȘ ‰‡Ô ¯ÚÔÓÈΤ˜ ÛÙÈÁ̤˜, Ì ·ÔÙ¤ÏÂ-ÛÌ· ÔÈ Û˘ÁÁÚ·Ê›˜ Ó· Û˘ÌÂÚ¿ÓÔ˘Ó, fiÙÈ Ë ÌÂٷΛÓËÛË ÛÙÚ¤„˘ ·ÔÙÂÏ› ÂÈ‚·Ú˘ÓÙÈÎfi Î·È fi¯È ÂÎÏ˘ÙÈÎfi ·Ú¿-ÁÔÓÙ· ÁÈ· ÙËÓ ·ÔÚÚfiÊËÛË ÙˆÓ ÚÈ˙ÒÓ, ·Ô‰›‰ÔÓÙ·˜ ¤ÙÛÈ ÙË ‰ËÌÈÔ˘ÚÁ›· ÙÔ˘ Ê·ÈÓÔ̤ÓÔ˘ ΢ڛˆ˜ Û ÁÂÓÂÙÈ-ÎÔ‡˜ ·Ú¿ÁÔÓÙ˜. ŸÛÔÓ ·ÊÔÚ¿ ÙȘ ‰˘Ó¿ÌÂȘ Ô˘ ÚÔηÏÔ‡Ó ÂÚÈÛÙÚÔÊ‹ (rotation) ÛÙ· ‰fiÓÙÈ·, ·˘Ù¤˜ ÛÙÚ¤ÊÔ˘Ó ÙÔ ‰fiÓÙÈ Á‡Úˆ ·fi ÙÔÓ ›‰ÈÔ ÙÔ˘ ÙÔÓ ¿ÍÔÓ· ÚÔηÏÒÓÙ·˜ ¤ÙÛÈ ÂÏ¿¯È-ÛÙ˜ ȤÛÂȘ ÛÙËÓ ÂÈÊ¿ÓÂÈ· ÙˆÓ ÚÈ˙ÒÓ ÙÔ˘˜ Î·È Î·Ù¿ Û˘Ó¤ÂÈ· ÂÚÈÔÚÈṲ̂ÓË ·ÔÚÚfiÊËÛË ÚÈ˙ÒÓ fiˆ˜ Ê¿ÓËΠ۠ÌÂϤÙ˜ Û ÂÈÚ·Ì·Ùfi˙ˆ· (Brain, 1969; Redlich Î·È Û˘Ó., 1996). øÛÙfiÛÔ, Û ÌÈ· ÚfiÛÊ·ÙË Û¯ÂÙÈο ÎÏÈÓÈ΋ ÌÂϤÙË ·Ú·ÙËÚ‹ıËÎ·Ó ÎÂÓÔÙfiÈ· ·ÔÚÚfiÊËÛ˘ ÛÙȘ ÂÈÊ¿ÓÂȘ ÙˆÓ ÚÈ˙ÒÓ fiÏˆÓ ÙˆÓ ÚÔÁÔÌÊ›ˆÓ Ô˘ ˘¤ÛÙËÛ·Ó ÂÚÈÛÙÚÔÊ‹, ÂÓÒ ·Ú¿Ï-ÏËÏ· ·˘Ù¤˜ ÔÈ ÂÚÈÔ¯¤˜ ·ÔÚÚfiÊËÛ˘ ÂÓÙÔ›˙ÔÓÙ·Ó ÛÙÔ Ì¤ÛÔ ÙÚÈÙËÌfiÚÈÔ Ù˘ Ú›˙·˜, Û ÂÚÈÔ¯¤˜ ‰ËÏ·‰‹ fiÔ˘ Ë ÌÔÚÊÔÏÔÁ›· Ù˘ Ú›˙·˜ ¤¯ÂÈ ÙËÓ ÌÂÁ·Ï‡ÙÂÚË ÚÔ‚ÔÏ‹ (Jimenez-Pellegrin Î·È Arana-Chavez, 2004). ∆¤ÏÔ˜, ÔÈ ÌÂÙ·ÎÈÓ‹ÛÂȘ ·ÏÈÓ‰ÚÔÌÈÎÔ‡ Ù‡Ô˘ (jiggling) ÙˆÓ ‰ÔÓÙÈÒÓ ÂÓÔ¯ÔÔÈ‹ıËÎ·Ó ˆ˜ ¤Ó·˜ ·ÎfiÌË Ì˯·ÓÈ-Îfi˜ ·Ú¿ÁÔÓÙ·˜ ÚfiÎÏËÛ˘ ·ÔÚÚfiÊËÛ˘ ÙˆÓ ÚÈ˙ÒÓ. √È ÌÂÙ·ÎÈÓ‹ÛÂȘ ·ÏÈÓ‰ÚÔÌÈÎÔ‡ Ù‡Ô˘ ‰ËÌÈÔ˘ÚÁÔ‡Ó Û˘ÁÎÏÂÈÛÈ·Îfi ÙÚ·‡Ì· ÙÔ ÔÔ›Ô ÌÔÚ› Ó· ÚÔηϤÛÂÈ ÙËÓ ÂÓÂÚÁÔÔ›ËÛË ÙÔ˘ Ì˯·ÓÈÛÌÔ‡ ¤Ó·Ú͢ ·ÔÚÚfi-ÊËÛ˘ ÙˆÓ ÚÈ˙ÒÓ ÙˆÓ ‰ÔÓÙÈÒÓ (Linge Î·È Linge 1983, 1991; Levander Î·È Û˘Ó., 1998a; Killiany, 1999; Brezniak Î·È Wasserstein, 1993b; Brezniak Î·È Wasserstein, 2002b). ∂ÈÚfiÛıÂÙ·, ‰È·ÈÛÙÒıËΠfiÙÈ Ë ·ÔÚÚfiÊËÛË ÙˆÓ ÚÈ˙ÒÓ ÙˆÓ ¿Óˆ ÁÔÌÊ›ˆÓ Â›Ó·È ·Úfi-ÌÔÈ·, ÙfiÛÔ ÛÙȘ ÂÚÈÙÒÛÂȘ Ô˘ ÔÈ ¿Óˆ ÁÔÌÊ›ÔÈ ¯ÚË-ÛÈÌÔÔÈÔ‡ÓÙ·È Î·Ù¿ ÙËÓ ‰È¿ÚÎÂÈ· Ù˘ Ó‡¯Ù·˜ ÁÈ· ÂÊ·Ú-ÌÔÁ‹ ÂÏ·ÛÙÈÎÒÓ ‰È·ÁÓ·ıÈÎÒÓ ‰˘Ó¿ÌˆÓ, fiÛÔ Î·È ÛÙȘ ÂÚÈÙÒÛÂȘ Ô˘ ¯ÚËÛÈÌÔÔÈÔ‡ÓÙ·È ÁÈ· Â͈ÛÙÔÌ·ÙÈ΋ ¤ÏÍË, ‹ ÁÈ· ÂÊ·ÚÌÔÁ‹ ˘ÂÚÒÈ·˜ ‰ÔÎÔ‡ ÙÔ˘ Ù‡Ô˘ Goshgarian (Alwali Î·È Û˘Ó., 2000). ∆¤ÏÔ˜, ÌÂÙ·ÎÈÓ‹-ÛÂȘ ·ÏÈÓ‰ÚÔÌÈÎÔ‡ Ù‡Ô˘ Î·È Û˘ÁÎÏÂÈÛȷο ÙÚ·‡Ì·Ù· Ì Â·ÎfiÏÔ˘ıÔ ÙË ‰ËÌÈÔ˘ÚÁ›· ·ÔÚÚÔÊ‹ÛÂˆÓ ÚÈ˙ÒÓ ÌÔÚÔ‡Ó Ó· ÚÔÎÏËıÔ‡Ó ·ÎfiÌË Î·È ·fi ÙȘ Û˘ÁÎÚ·ÙË-ÙÈΤ˜ Û˘Û΢¤˜ Ô˘ ÙÔÔıÂÙÔ‡ÓÙ·È ÌÂÙ¿ ÙÔ ¤Ú·˜ Ù˘ ÔÚıÔ‰ÔÓÙÈ΋˜ ıÂÚ·›·˜ (Copeland Î·È Green, 1986). ∫ ∫ÈÈÓÓËËÙÙ¤¤˜˜ Îη·ÈÈ ··ÎΛ›ÓÓËËÙÙ˜˜ ÔÔÚÚııÔÔ‰‰ÔÔÓÓÙÙÈÈÎΤ¤˜˜ ÛÛ˘˘ÛÛÎ΢˘¤¤˜˜ ∏ ¯Ú‹ÛË ·ÎÈÓ‹ÙˆÓ ÔÚıÔ‰ÔÓÙÈÎÒÓ Û˘Û΢ÒÓ Î·È Ë Â›-‰Ú·ÛË ÙÔ˘˜ ÛÙÔÓ Ì˯·ÓÈÛÌfi ¤Ó·Ú͢ Ù˘ ·ÔÚÚfiÊË-Û˘ ÙˆÓ ÚÈ˙ÒÓ ·ÂÙ¤ÏÂÛ ÁÈ· ÔÏÏ¿ ¯ÚfiÓÈ·

·ÓÙÈΛÌÂ-tral incisors, whereas for the rest of the teeth, such a great resorption was observed only in 1% of the patients. Levander et al. (1998b) observed that root resorption was more significant in patients with multiple congenital missing teeth (4-16 missing teeth) than in patients having 1-3 missing teeth, as well as in cases with teeth having abnormal root structure.

A comparison between Begg and Tweed techniques revealed that there is no difference between them in the extent of induced resorption (Beck and Harris, 1994), while the comparison between Begg and ∂dgewise tech-niques revealed that orthodontic treatment with Begg technique induce 2.3 times more resorption on the roots of the posterior teeth than ∂dgewise technique (McNab et al., 2000). Moreover, when extractions have been per-formed during treatment, root resorption was 3.7 times greater.

In a comparative study between Standard Edgewise and Straight Wire techniques in a homogeneous sample of patients with Class I malocclusions treated with extractions of at least two upper first premolars, it was found that the upper central incisors presented stati-cally more significant root resorption when the Stan-dard Edgewise technique was used, while there was no difference between the two techniques in root resorp-tion of the upper lateral incisors (Mavragani et al., 2000). In a more recent study, however, no statistically significant difference was found between Standard Edgewise and Straight Wire techniques in root resorp-tion of the central and lateral incisors (Mohandesan et al., 2007).

From the comparative study among 3 techniques, the Simplified Standard Edgewise, the Straight Wire and the Bioefficient Therapy, it was found that the group of the patients treated with the Bioefficient Therapy pre-sented the least root resorptions. These findings were attributed to the use of superelastic archwires and the corresponding brackets used with each technique, to the use of rectangular stainless steel archwires with a smaller cross-section (0.018x0.025 inch placed in brack-ets with 0.022x0.028 inch slot) for the distalization of the incisors, as well as to the procedures taking place with each one of the techniques during the last phase of the orthodontic treatment (finishing) (Janson et al., 2000).

According to the above mentioned findings it seems that up until today it cannot be concluded that a specific technique is more advantageous than the others con-cerning the phenomenon of root resorption of ortho-dontically moved teeth.

ÓÔ ¤Ú¢ӷ˜ ÌÈ·˜ ÏËıÒÚ·˜ ÂÚÁ·ÛÈÒÓ (Ketcham, 1927; Massler Î·È Malone, 1954; Kvam, 1972a,b; Newman, 1975; Malmgren Î·È Û˘Ó., 1982; Copeland Î·È Green, 1986; Beck Î·È Harris, 1994; Baumrind Î·È Û˘Ó., 1996; Î·È ÔÏÏÔ› ¿ÏÏÔÈ). øÛÙfiÛÔ, ÔÈ ÌÂϤÙ˜ Ô˘ ·ÊÔÚÔ‡Ó ÙË Û‡ÁÎÚÈÛË ÌÂٷ͇ ÎÈÓËÙÒÓ Î·È ·Î›ÓËÙˆÓ ÔÚıÔ‰ÔÓÙÈ-ÎÒÓ Û˘Û΢ÒÓ Î·È ÙËÓ Â›‰Ú·Û‹ ÙÔ˘˜ ÛÙËÓ ·ÔÚÚfi-ÊËÛË ÙˆÓ ÚÈ˙ÒÓ Â›Ó·È ÂÚÈÔÚÈṲ̂Ó˜. ™Â Ì›· ·Ó¿ÏÔÁË Ù¤ÙÔÈ· ÌÂϤÙË ‰È·ÈÛÙÒıËΠfiÙÈ Ë ÂÊ·ÚÌÔÁ‹ ·ÎÈÓ‹ÙˆÓ Û˘Û΢ÒÓ ‹Ù·Ó ÈÔ ÂÈ‚Ï·‚‹˜ ÁÈ· ÙÔ ·ÎÚÔÚÚ›˙ÈÔ ÙˆÓ ‰ÔÓÙÈÒÓ (Linge Î·È Linge, 1983). ∞Ó¿ÏÔÁ· Û˘ÌÂÚ¿-ÛÌ·Ù· ÚÔ¤Ú¯ÔÓÙ·È Î·È ·fi ¿ÏÏË Û˘ÁÎÚÈÙÈ΋ ÌÂϤÙË ·ÛıÂÓÒÓ 10 ¯ÚfiÓÈ· ÌÂÙ¿ ÙËÓ ÔÚıÔ‰ÔÓÙÈ΋ ıÂÚ·›·, fiÔ˘ ·Ú·ÙËÚ‹ıËΠ·ÔÚÚfiÊËÛË ÚÈ˙ÒÓ ÛÙo˘˜ ·ÛıÂ-Ó›˜ ÛÙÔ˘˜ ÔÔ›Ô˘˜ ÙÔÔıÂÙ‹ıËÎ·Ó ·Î›ÓËÙ˜ Û˘Û΢¤˜ (Kennedy Î·È Û˘Ó., 1983). ∞Ó·ÌÊ›‚ÔÏ·, Ë Û‡ÁÎÚÈÛË ÌÂٷ͇ ÎÈÓËÙÒÓ Î·È ·ÎÈÓ‹ÙˆÓ Û˘Û΢ÒÓ, ÂÓÔ¯ÔÔÈ› ÙȘ ‰Â‡ÙÂÚ˜. øÛÙfiÛÔ Î·È ÔÈ ÎÈÓËÙ¤˜ Û˘Û΢¤˜ ‰ÂÓ ÂÍ·È-ÚÔ‡ÓÙ·È ˆ˜ Èı·Ófi˜ ·ÈÙÈÔÏÔÁÈÎfi˜ ·Ú¿ÁÔÓÙ·˜ Ù˘ ·ÔÚÚfiÊËÛ˘ ÙˆÓ ÚÈ˙ÒÓ, ·fi ÙË ÛÙÈÁÌ‹ Ô˘ ÂÓÔ¯Ô-ÔÈÔ‡ÓÙ·È ÁÈ· ÚfiÎÏËÛË Û˘ÁÎÏÂÈÛÈ·ÎÒÓ ÙÚ·˘Ì¿ÙˆÓ Î·È ÌÂÙ·ÎÈÓ‹ÛÂȘ Ù·Ï¿ÓÙˆÛ˘, ÂȉÚÒÓÙ·˜ Ì ·˘Ùfi ÙÔÓ ÙÚfiÔ ‚Ï·ÙÈο ÛÙÔ ·ÎÚÔÚÚ›˙ÈÔ ÙˆÓ ‰ÔÓÙÈÒÓ (Linge Î·È Linge, 1983; Odenrick Î·È Brattstrom, 1985; Copeland Î·È Green, 1986). √ √ÚÚııÔÔ‰‰ÔÔÓÓÙÙÈÈÎΤ¤˜˜ ÙÙ¯¯ÓÓÈÈÎΤ¤˜˜ √ ÛËÌ·ÓÙÈÎfi˜ ·ÚÈıÌfi˜ ÙˆÓ ‰È·ÊfiÚˆÓ Ù¯ÓÈÎÒÓ Ô˘ ¯ÚËÛÈÌÔÔÈÔ‡ÓÙ·È Û‹ÌÂÚ·, ‰ÂÓ Î·ıÈÛÙ¿ ÂÊÈÎÙ‹ ÌÈ· Û˘ÁÎÚÈÙÈ΋ ÌÂϤÙË ÌÂٷ͇ ÙÔ˘˜. ∆· ˘¿Ú¯ÔÓÙ· ‰Â‰Ô̤-Ó· ÚÔ¤Ú¯ÔÓÙ·È ¿ÏÏÔÙ ·fi ÙËÓ ·ÍÈÔÏfiÁËÛË ÌÈ·˜ ÌfiÓÔ Ù¯ÓÈ΋˜, ¿ÏÏÔÙ ·fi ÙË Û‡ÁÎÚÈÛË 2 Ù¯ÓÈÎÒÓ, ÂÓÒ Ì›· ÂÚÁ·Û›· ·Ó·Ê¤ÚÂÙ·È ÛÙË Û˘ÁÎÚÈÙÈ΋ ÌÂϤÙË 3 Ù¯ÓÈÎÒÓ. ŸÛÔÓ ·ÊÔÚ¿ ÙËÓ Ù¯ÓÈ΋ Edgewise, ÔÈ Kaley Î·È Phillips (1991) ‰È·›ÛÙˆÛ·Ó fiÙÈ Û ¤Ó· ‰Â›ÁÌ· 200 ·ÛıÂÓÒÓ, ÔÛÔÛÙfi 3% ·ÚÔ˘Û›·Û ÛËÌ·ÓÙÈ΋ ·ÔÚ-ÚfiÊËÛË (ÌÂÁ·Ï‡ÙÂÚË ·fi ÙÔ 1/4 ÙÔ˘ Ì‹ÎÔ˘˜) Ù˘ Ú›˙·˜ ÙˆÓ ‰‡Ô ¿Óˆ ÎÂÓÙÚÈÎÒÓ ÙÔ̤ˆÓ, ÂÓÒ ÛÙ· ˘fiÏÔÈ· ‰fiÓÙÈ· Ù¤ÙÔÈ·˜ ¤ÎÙ·Û˘ ·ÔÚÚfiÊËÛË ‰È·ÈÛÙÒıËΠÌfiÓÔ Û ÔÛÔÛÙfi 1% ÙˆÓ ·ÛıÂÓÒÓ. √È Levander Î·È Û˘Ó. (1998b), ·Ú·Ù‹ÚËÛ·Ó fiÙÈ Ë ·ÔÚÚfiÊËÛË Ù˘ Ú›˙·˜ ‹Ù·Ó ÛËÌ·ÓÙÈÎfiÙÂÚË Û ·ÛıÂÓ›˜ Ì ÔÏÏ·Ϥ˜ Û˘ÁÁÂÓ›˜ ÂÏÏ›„ÂȘ ‰ÔÓÙÈÒÓ (4-16 ÂÏÏ›ÔÓÙ· ‰fiÓÙÈ·) ·fi fiÙÈ Û ·ÛıÂÓ›˜ Ô˘ ›¯·Ó 1-3 ÂÏÏ›ÔÓÙ· ‰fiÓÙÈ·, ηıÒ˜ Î·È ÛÙȘ ÂÚÈÙÒÛÂȘ ‰ÔÓÙÈÒÓ Ô˘ ·ÚÔ˘Û›·˙·Ó ·ÓÒÌ·ÏË ‰ÔÌ‹ Ú›˙·˜. ™˘ÁÎÚ›ÓÔÓÙ·˜ ÙËÓ Ù¯ÓÈ΋ Begg Î·È ÙËÓ Ù¯ÓÈ΋ Tweed, ‰È·ÈÛÙÒıËΠfiÙÈ ‰ÂÓ ˘¿Ú¯ÂÈ ‰È·ÊÔÚ¿ ÌÂٷ͇ ÙˆÓ ‰‡Ô Ù¯ÓÈÎÒÓ ÛÙÔ Â‡ÚÔ˜ Ù˘ ·ÔÚÚfiÊËÛ˘ Ô˘ ˘Ê›-O

Orrtthhooddoonnttiicc wwiirreess

During orthodontic treatment, hyperelastic Ni-Ti and stainless steel wires are commonly used. During the peri-od of deactivation, a stable light force is transmitted for a longer period with the hyperelastic wires, whereas with the stainless steel wires, the applied force is of greater magnitude and it reduces very quickly (Reitan, 1985, Miura et al., 1986; Reitan and Rygh, 1994; Maltha and Dijkman, 1996; Faltin et al., 2001). According to a study with a laser scanning electron microscope, in which a comparison of root resorption of premolars in adolescents with a mean age of 12.5 years was per-formed, after the use of hyperelastic and stainless steel wires, it was found that the surface, as well as the perimeter and the volume of resortion’s cenotopia were significant greater (in a percentage of 140%) when the teeth were removed with hyperelastic wires compared with stainless steel wires. This result was attributed to the possibility of high force application (0.8-1.0 ¡) used in this study (Weiland, 2003). However, it is reported that the action of these wires further depends on the magni-tude and the duration of the applied forces, as well as on individual variations (Linge and Linge, 1983; Maltha and Dijkman, 1996; Weiland, 2003, 2006).

T

Tyyppee ooff oorrtthhooddoonnttiicc ffoorrcceess

Several researches seem to lead to conflicting conclu-sions concerning the type of orthodontic force that should be applied in order to minimize the phenomenon of root resorption.

Owman-Moll et al. (1995) did not found any significant differences in the extent of root resorptions caused by the application of continuous or interrupted forces. In contrast, Maltha and Dijkman (1996) and Maltha et al. (2004) found out in experimental studies in dogs that interrupted forces induce root resorptions of less extent compared to continuous forces. Acar et al. (1999) came to similar conclusions after a clinical study in patients treated with extractions of first premolars.

The differences among the above mentioned findings could possibly attributed to the fact that these studies are not comparable, as they differ in the technique used and the duration of the applied forces. For example, the findings of Owman-Moll et al. (1995) derive from the application of continuous forces for 24 hours and inter-rupted forces for one every four weeks, the findings of Maltha and Dijkman (1996) refer to interrupted forces applied for 16 hours per day, whereas these of Acar et al.

ÛÙ·ÓÙ·È Ù· ‰fiÓÙÈ· (Beck Î·È Harris, 1994), ÂÓÒ Û˘ÁÎÚ›-ÓÔÓÙ·˜ ÙȘ Ù¯ÓÈΤ˜ Begg Î·È ∂dgewise, ‰È·ÈÛÙÒıËΠfiÙÈ Ë ÔÚıÔ‰ÔÓÙÈ΋ ıÂÚ·›· Ì ÙËÓ Ù¯ÓÈ΋ Begg ÚÔη-Ï› 2,3 ÊÔÚ¤˜ ÂÚÈÛÛfiÙÂÚË ·ÔÚÚfiÊËÛË ÛÙȘ Ú›˙˜ ÙˆÓ ÔÈÛı›ˆÓ ‰ÔÓÙÈÒÓ Û ۯ¤ÛË Ì ÙËÓ Ù¯ÓÈ΋ ∂dgewise (McNab Î·È Û˘Ó., 2000). ∂ÈϤÔÓ, fiÙ·Ó Î·Ù¿ ÙËÓ ‰È¿ÚÎÂÈ· Ù˘ ıÂÚ·›·˜ ¤ÁÈÓ·Ó ÂÍ·ÁˆÁ¤˜, Ë ·ÔÚÚfiÊËÛË ÙˆÓ ÚÈ˙ÒÓ ‹Ù·Ó 3,7 ÊÔÚ¤˜ ÌÂÁ·Ï‡ÙÂÚË. ™Â Ì›· Û˘ÁÎÚÈÙÈ΋ ÌÂϤÙË ÌÂٷ͇ Ù˘ Ù¯ÓÈ΋˜ Standard Edgewise Î·È Ù˘ Ù¯ÓÈ΋˜ Straight Wire Û ¤Ó· ÔÌÔÈÔÁÂ-Ó¤˜ ‰Â›ÁÌ· ·ÛıÂÓÒÓ ÌÂ Û˘ÁÎÏÂÈÛȷΤ˜ ·ÓˆÌ·Ï›Â˜ ∆¿Í˘ ππ, ηÙËÁÔÚ›·˜ 1 ηٿ Angle Ô˘ ıÂÚ·‡ÙËÎ·Ó Ì ÂÍ·ÁˆÁ¤˜ ÙÔ˘Ï¿¯ÈÛÙÔÓ ÙˆÓ ‰‡Ô ¿Óˆ ÚÒÙˆÓ ÚÔÁÔÌÊ›ˆÓ, ·Ú·ÙË-Ú‹ıËΠfiÙÈ ÔÈ ¿Óˆ ÎÂÓÙÚÈÎÔ› ÙÔÌ›˜ ·ÚÔ˘Û›·˙·Ó ÛÙ·ÙÈÛÙÈ-ο ÛËÌ·ÓÙÈÎfiÙÂÚË ·ÔÚÚfiÊËÛË ÚÈ˙ÒÓ Ì ¯Ú‹ÛË Ù˘ Ù¯ÓÈ-΋˜ Standard Edgewise, ÂÓÒ ‰ÂÓ ˘‹ÚÍ η̛· ‰È·ÊÔÚ¿ ÛÙËÓ ·ÔÚÚfiÊËÛË ÚÈ˙ÒÓ ÙˆÓ ¿Óˆ Ï·Á›ˆÓ ÙÔ̤ˆÓ ÌÂÙ·-͇ ÙˆÓ ‰‡Ô Ù¯ÓÈÎÒÓ (Mavragani Î·È Û˘Ó., 2000). ŸÌˆ˜ Û ÌÈ· ÈÔ ÚfiÛÊ·ÙË ÌÂϤÙË ‰ÂÓ ‚Ú¤ıËΠÛÙ·ÙÈÛÙÈο ÛËÌ·-ÓÙÈ΋ ‰È·ÊÔÚ¿ ÌÂٷ͇ Ù˘ Ù¯ÓÈ΋˜ Standard Edgewise Î·È Straight Wire ÛÙËÓ ·ÔÚÚfiÊËÛË Ô˘ ·ÚÔ˘Û›·˙·Ó ÔÈ Ú›˙˜ ÙˆÓ ÎÂÓÙÚÈÎÒÓ Î·È Ï·Á›ˆÓ ÙÔ̤ˆÓ (Mohandesan Î·È Û˘Ó., 2007). ∞fi ÙËÓ Û˘ÁÎÚÈÙÈ΋ ÌÂϤÙË ÌÂٷ͇ 3 Ù¯ÓÈÎÒÓ, ÙËÓ Simplified Standard Edgewise, ÙËÓ Straight Wire Î·È ÙËÓ Bioefficient Therapy, ‰È·ÈÛÙÒıËΠfiÙÈ Ë ÔÌ¿‰· ·ÛıÂÓÒÓ Ô˘ ıÂÚ·‡ÙËÎ·Ó Ì ÙËÓ Bioefficient Therapy ·ÚÔ˘Û›·-˙·Ó ÙȘ ÌÈÎÚfiÙÂÚ˜ ·ÔÚÚÔÊ‹ÛÂȘ ÚÈ˙ÒÓ. ∆· Â˘Ú‹Ì·Ù· ·˘Ù¿ ·Ô‰fiıËÎ·Ó ÙfiÛÔ ÛÙË ¯Ú‹ÛË ÙˆÓ ˘ÂÚÂÏ·ÛÙÈÎÒÓ Û˘ÚÌ¿ÙˆÓ Î·È ÙˆÓ ·ÓÙÈÛÙÔ›¯ˆÓ ·ÁÎ˘Ï›ˆÓ Ô˘ ¯ÚËÛÈÌÔ-ÔÈÔ‡ÓÙ·È ÛÙËÓ Î¿ı Ù¯ÓÈ΋, fiÛÔ Î·È ÛÙË ¯Ú‹ÛË ÌÈÎÚfiÙÂ-Ú˘ ‰È·ÙÔÌ‹˜ ÙÂÙÚ¿ÁˆÓˆÓ Û˘ÚÌ¿ÙˆÓ ·ÓÔÍ›‰ˆÙÔ˘ ¯¿Ï˘-‚· (‰È·ÙÔÌ‹˜ 0.018x0.025 inch ÙÔÔıÂÙË̤ӷ Û ·Á·ÏÈ· Ì ‰È·ÙÔÌ‹ 0.022x0.028 inch), Ù· ÔÔ›· ¯ÚËÛÈÌÔÔÈ‹ıË-Î·Ó ÁÈ· ÙËÓ ÚÔ˜ Ù· ¿ˆ ÌÂٷΛÓËÛË ÙˆÓ ÙÔ̤ˆÓ, fiˆ˜ Â›Û˘ Î·È ÛÙȘ ‰È·‰Èηۛ˜ Ô˘ Ï·Ì‚¿ÓÔ˘Ó ¯ÒÚ· Ì ÙËÓ Î¿ı ÌÈ· Ù¯ÓÈ΋ ÛÙÔ ÙÂÏÂ˘Ù·›Ô ıÂÚ·¢ÙÈÎfi ÛÙ¿‰ÈÔ Ù˘ ÔÚıÔ‰ÔÓÙÈ΋˜ ıÂÚ·›·˜ (finishing) (Janson Î·È Û˘Ó., 2000). ∞fi Ù· ·Ú·¿Óˆ Ê·›ÓÂÙ·È Û˘ÓÂÒ˜ fiÙÈ Ì¤¯ÚÈ Î·È Û‹ÌÂÚ· ‰ÂÓ ÌÔÚ› Ó· ÙÂÎÌËÚȈı› fiÙÈ ÌÈ· Û˘ÁÎÂÎÚÈ̤ÓË Ù¯ÓÈ΋ ˘ÂÚÙÂÚ› ÛËÌ·ÓÙÈο ¤Ó·ÓÙÈ Î¿ÔÈ·˜ ¿ÏÏ˘ fiÛÔÓ ·ÊÔÚ¿ ÙÔ Ê·ÈÓfiÌÂÓÔ Ù˘ ·ÔÚÚfiÊËÛ˘ ÙˆÓ ÚÈ˙ÒÓ ÙˆÓ ‰ÔÓÙÈÒÓ Ù· ÔÔ›· ÌÂÙ·ÎÈÓÔ‡ÓÙ·È ÔÚıÔ‰ÔÓÙÈο. √ √ÚÚııÔÔ‰‰ÔÔÓÓÙÙÈÈÎο¿ ÛÛ‡‡ÚÚÌÌ··ÙÙ·· ∫·Ù¿ ÙË ‰È¿ÚÎÂÈ· Ù˘ ÔÚıÔ‰ÔÓÙÈ΋˜ ıÂÚ·›·˜, ¯ÚËÛÈÌÔ-ÔÈÔ‡ÓÙ·È Û˘Ó‹ıˆ˜ ˘ÂÚÂÏ·ÛÙÈο Û‡ÚÌ·Ù· ÓÈÎÂÏ›Ô˘-ÙÈÙ·-Ó›Ô˘ Î·È ¿Î·ÌÙ· Û‡ÚÌ·Ù· ·ÓÔÍ›‰ˆÙÔ˘ ¯¿Ï˘‚·. ∫·Ù¿

(1999) refer to the application of elastic forces in the same patient either for 24 hours (continuous forces) or for 12 hours per 24-hour (interrupted forces)

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According to the existing research data, it seems that it is not possible to give a well documented answer regard-ing the selection of usregard-ing light or heavy orthodontic forces. The use of light forces minimize the risk of root resorption according to Reitan (1985), whereas histolog-ical findings of other studies do not support a difference between light and heavy orthodontic forces (Owman-Moll, 1995; Owman-Moll et al., 1996a,b).

It is reported that the heavier the applied forces the higher the applied stress per root surface unit, and thus the more severe the root resorption (Harry and Sims, 1982; Mayoral, 1982; Reitan, 1985; Linge and Linge, 1991; Reitan and Rygh, 1994). However, even after the application of continuous light forces of 50 gr, it seems that no matter how small the applied force is, root resorptions are observed, possibly due to the duration of force application (Kurol et al., 1996). There are, however, some conflicting data. For example, in an histological study performed by Owman-Moll et al. (1996a,b) on pre-molars, it was found that despite the duplication or the quadruplication of the force magnitude from 50 to 200 gr, no statistical significant difference was found in the amount of the root resorption observed. Similar conclu-sions have reached other researchers who did not found any correlation between root resorption and the magni-tude of the applied force, and for that reason they ascribe root resorption mainly to genetic and predisposi-tion factors (Al-Qawasmi et al., 2003; Artun et al., 2005; van Loenen et al., 2007). In a more recent study with scanning electron microscope (SEM), in which root resorptions of first premolars were volumetric assessed after the application of light and heavy forces, greater resorption was found after the application of heavy forces (Darendeliler et al., 2004; Chan and Darendeliler, 2005). To similar conclusions came also other studies using SEM in rats (Gonzales et al., 2008) and microcom-puted tomography in humans (Cheng et al., 2009), in which less root resorption was observed using light than heavy orthodontic forces.

T

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The number of published studies investigating the degree of root resorption induced by orthodontic

treat-ÙËÓ ÂÚ›Ô‰Ô Ù˘ ·ÂÓÂÚÁÔÔ›ËÛ˘, Ì ٷ ˘ÂÚÂÏ·ÛÙÈο Û‡ÚÌ·Ù· ÌÂÙ·‚È‚¿˙ÂÙ·È ÌÈ· ÛÙ·ıÂÚ‹ ‰‡Ó·ÌË ‹È·˜ ¤ÓÙ·-Û˘ ÁÈ· ÌÂÁ·Ï‡ÙÂÚÔ ¯ÚÔÓÈÎfi ‰È¿ÛÙËÌ·, ÂÓÒ Ì ٷ Û‡ÚÌ·-Ù· ·ÓÔÍ›‰ˆÙÔ˘ ¯¿Ï˘‚· Ë ·ÛÎÔ‡ÌÂÓË ‰‡Ó·ÌË Â›Ó·È ÌÂÁ·-χÙÂÚ˘ ¤ÓÙ·Û˘ Î·È ÂÏ·ÙÙÒÓÂÙ·È Ù·¯‡Ù·Ù· (Reitan, 1985, Miura Î·È Û˘Ó., 1986; Reitan Î·È Rygh, 1994; Maltha Î·È Dijkman, 1996; Faltin Î·È Û˘Ó., 2001). ™‡Ìʈӷ Ì ÌÈ· ÌÂϤÙË Ì ÌÈÎÚÔÛÎfiÈÔ Û¿ÚˆÛ˘ Ì laser, fiÔ˘ ¤ÁÈÓ ۇÁÎÚÈÛË Ù˘ ·ÔÚÚfiÊËÛ˘ ÙˆÓ ÚÈ˙ÒÓ ÙˆÓ ÚÔÁÔÌÊ›ˆÓ Û ¤ÊË‚Ô˘˜ Ì ̤ÛË ËÏÈΛ· 12.5 ¤ÙË, ÌÂÙ¿ ·fi ¯Ú‹ÛË ˘Â-ÚÂÏ·ÛÙÈÎÒÓ Û˘ÚÌ¿ÙˆÓ Î·È Û˘ÚÌ¿ÙˆÓ ·fi ·ÓÔÍ›‰ˆÙÔ ¯¿Ï˘‚·, ‰È·ÈÛÙÒıËΠfiÙÈ ÙfiÛÔ Ë ÂÈÊ¿ÓÂÈ·, fiÛÔ Ë ÂÚ›-ÌÂÙÚÔ˜ Î·È Ô fiÁÎÔ˜ ÙˆÓ ÎÂÓÔÙÔ›ˆÓ ·ÔÚÚfiÊËÛ˘ ‹Ù·Ó ÛËÌ·ÓÙÈο ÌÂÁ·Ï‡ÙÂÚ· (Û ÔÛÔÛÙfi 140%) fiÙ·Ó Ù· ‰fiÓÙÈ· ÌÂÙ·ÎÈÓ‹ıËÎ·Ó Ì ˘ÂÚÂÏ·ÛÙÈο Û‡ÚÌ·Ù·, Û ۇÁÎÚÈÛË Ì ÙÔ˘ ·ÓÔÍ›‰ˆÙÔ˘ ¯¿Ï˘‚·, ·Ô‰›‰ÔÓÙ·˜ ÙÔ ·ÔÙ¤ÏÂÛÌ· ·˘Ùfi, ÛÙËÓ Èı·ÓfiÙËÙ· ÂÊ·ÚÌÔÁ‹˜ ÌÂÁ¿Ï˘ ‰‡Ó·Ì˘ (0,8-1,0 ¡) ÛÙË ÌÂϤÙË ·˘Ù‹ (Weiland, 2003). øÛÙfiÛÔ, ·Ó·Ê¤-ÚÂÙ·È fiÙÈ Ë ‰Ú¿ÛË ·˘Ù‹ ÙˆÓ Û˘ÚÌ¿ÙˆÓ, ÂÍ·ÚÙ¿Ù·È Î·È ·fi ÙËÓ ¤ÓÙ·ÛË Î·È ÙËÓ ¯ÚÔÓÈ΋ ‰È¿ÚÎÂÈ· ÙˆÓ ÂÍ·ÛÎÔ‡ÌÂÓˆÓ ‰˘Ó¿ÌˆÓ, ηıÒ˜ Î·È ·fi ·ÙÔÌÈΤ˜ ‰È·Î˘Ì¿ÓÛÂȘ (Linge Î·È Linge, 1983; Maltha Î·È Dijkman, 1996; Weiland, 2003, 2006). ∂ ∂››‰‰ÔÔ˜˜ ÔÔÚÚııÔÔ‰‰ÔÔÓÓÙÙÈÈÎÎÒÒÓÓ ‰‰˘˘ÓÓ¿¿Ì̈ˆÓÓ √È ‰È¿ÊÔÚÔÈ ÂÚ¢ÓËÙ¤˜ Ê·›ÓÂÙ·È Ó· ηٷϋÁÔ˘Ó Û ·ÓÙÈ-ÎÚÔ˘fiÌÂÓ˜ ·fi„ÂȘ fiÛÔÓ ·ÊÔÚ¿ ÙÔ Â›‰Ô˜ Ù˘ ÔÚıÔ‰ÔÓÙÈ-΋˜ ‰‡Ó·Ì˘ Ô˘ ı· Ú¤ÂÈ Ó· ÂÊ·ÚÌÔÛÙ› ÚÔÎÂÈ̤ÓÔ˘ Ó· ÂÏ·¯ÈÛÙÔÔÈËı› ÙÔ Ê·ÈÓfiÌÂÓÔ Ù˘ ‰ËÌÈÔ˘ÚÁ›·˜ Ù˘ ·ÔÚÚfiÊËÛ˘ ÙˆÓ ÚÈ˙ÒÓ. ŒÙÛÈ, Ô Owman-Moll Î·È Û˘Ó. (1995) ‰ÂÓ ·Ú·Ù‹ÚËÛ·Ó ÛËÌ·ÓÙÈΤ˜ ‰È·ÊÔÚ¤˜ ÛÙÔ Ì¤ÁÂıÔ˜ Ù˘ ·ÔÚÚfiÊËÛ˘ ÙˆÓ ÚÈ˙ÒÓ ÙˆÓ ‰ÔÓÙÈÒÓ Ô˘ ÚÔηÏÔ‡ÓÙ·È ÌÂÙ¿ ·fi ÂÊ·ÚÌÔ-Á‹ Û˘Ó¯ÒÓ ‹ ‰È·ÎÔÙfiÌÂÓˆÓ ‰˘Ó¿ÌˆÓ. ∞ÓÙ›ıÂÙ·, ÔÈ Maltha Î·È Dijkman (1996) Î·È Maltha Î·È Û˘Ó. (2004) ‰È·›ÛÙˆÛ·Ó Û ÂÈÚ·Ì·ÙÈΤ˜ ÌÂϤÙ˜ Û Û·ÏÔ˘˜ fiÙÈ ÔÈ ‰È·ÎÔÙfiÌÂÓ˜ ‰˘Ó¿ÌÂȘ ÚÔηÏÔ‡Ó ÌÈÎÚfiÙÂÚ˘ ¤ÎÙ·Û˘ ·ÔÚÚÔÊ‹ÛÂȘ ÚÈ˙ÒÓ ·fi fiÙÈ ÔÈ Û˘Ó¯›˜ ‰˘Ó¿ÌÂȘ. ™Â ·ÚfiÌÔÈ· Û˘ÌÂÚ¿ÛÌ·Ù· η٤ÏËÍ·Ó Î·È ÔÈ Acar Î·È Û˘Ó. (1999) Û ÌÈ· ÎÏÈÓÈ΋ ÌÂϤÙË Û ·ÛıÂÓ›˜ ÛÙÔ˘˜ ÔÔ›Ô˘˜ Ú·ÁÌ·ÙÔÔÈ‹ıËÎ·Ó ÂÍ·ÁˆÁ¤˜ ÙˆÓ ÚÒÙˆÓ ÚÔÁÔÌÊ›ˆÓ ÛÙ· Ï·›ÛÈ· Ù˘ ÔÚıÔ‰ÔÓÙÈ΋˜ ÙÔ˘˜ ıÂÚ·›·˜. √È ‰È·ÊÔÚ¤˜ ÌÂٷ͇ ÙˆÓ ·Ú·¿Óˆ ¢ÚËÌ¿ÙˆÓ ı· ÌÔ-ÚÔ‡Û·Ó Èı·Ó¿ Ó· ·Ô‰ÔıÔ‡Ó ÛÙÔ ÁÂÁÔÓfi˜ fiÙÈ ÔÈ ÌÂϤÙ˜ ·˘Ù¤˜ ‰ÂÓ Â›Ó·È Û˘ÁÎÚ›ÛÈ̘ ηı’ fiÛÔÓ ‰È·ÊÔÚÔÔÈÔ‡ÓÙ·È ÙfiÛÔ ˆ˜ ÚÔ˜ ÙËÓ Ù¯ÓÈ΋ fiÛÔ Î·È ÛÙË ¯ÚÔÓÈ΋ ‰È¿ÚÎÂÈ· ÙˆÓ ÂÊ·ÚÌÔ˙fiÌÂÓˆÓ ‰˘Ó¿ÌˆÓ. ŒÙÛÈ, Ù· Â˘Ú‹Ì·Ù· ÙÔ˘ Owman-Moll Î·È Û˘Ó. (1995) ÚÔ¤Ú¯ÔÓÙ·È ·fi ÂÊ·ÚÌÔÁ‹ ÙfiÛÔ Û˘Ó¯ÒÓ ‰˘Ó¿ÌÂˆÓ Â› 24ˆÚ˘ ‚¿Û˘, fiÛÔ Î·È

‰È·-ment in relation to the type of malocclusion is limited and their results lead to conflicting conclusions. Mirabel-la and Artun (1995b) did not found any correMirabel-lation between initial malocclusion and root resorption. Similar results found also Fritz et al. (2003). On the contrary, Taner et al. (1999) observed in patients with Class I and Class II malocclusions treated with premolars extrac-tions, that the upper incisors in Class II Division 1 patients presented a higher amount of root resorption compared to Class I patients. Similar results found by Brin et al. (2003), who retrospectively evaluated ortho-dontic treatment of Class II patients and concluded that there is a good correlation between root resorption and the amount of the initial overjet as well as the time peri-od that the patient was under treatment with fixed appliances.

The studies assessing root resorptions following treat-ment of Class III malocclusion are also limited. Kaley and Phillips (1991) who studied root resorption after ortho-dontic treatment in patients with Class III malocclusion observed that the upper central incisors in a percentage of 90%, as well as the upper lateral incisors in a some-what smaller percentage, had undergone severe resorp-tion, which was visible after careful examination of panoramic radiographs. This was attributed to the possi-bility of heavy pressure of these teeth against the corti-cal bone during orthodontic treatment, because of the profound labial inclination that these teeth frequently show after the end of orthodontic treatment in order to compensate the skeletal Class III jaw relationship. Finally, open bite treatment also seems to be a risk fac-tor for induction of root resorption, something that could be attributed to the jiggling movements of the incisors or the diminished bone anchorage mainly at the anterior teeth, combined with tongue dysfunction (Odenrick and Brattstrom, 1985; Linge and Linge, 1991; Harris and Butler, 1992). However, this is in contrast to the findings of Katsaros and Berg (1993), who reported that only a small number of patients with open bite showed root resorption after orthodontic treatment (greater than 10% of the initial root length). These patients had a history of trauma or atypical root shape. D

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Many researchers support the idea that root resorption risk increases as the duration of the orthodontic treat-ment increases. In clinical studies it has been observed that there is root resorption even after the first 6 months of active orthodontic treatment, with a consequent

ÎÔÙfiÌÂÓˆÓ ÁÈ· Ì›· ‚‰ÔÌ¿‰· οı 4 ‚‰ÔÌ¿‰Â˜, Ù· Â˘Ú‹Ì·Ù· ÙˆÓ Maltha Î·È Dijkman (1996) ·ÊÔÚÔ‡Ó ‰È·-ÎÔÙfiÌÂÓ˜ ‰˘Ó¿ÌÂȘ Ô˘ ÂÊ·ÚÌÔ˙fiÙ·Ó 16 ÒÚ˜ ÙËÓ Ë̤ڷ, ÂÓÒ ÙˆÓ Acar Î·È Û˘Ó. (1999) ·ÊÔÚÔ‡Ó ÂÊ·ÚÌÔÁ‹ ÂÏ·ÛÙÈÎÒÓ ‰˘Ó¿ÌÂˆÓ ·fi ÙÔÓ ›‰ÈÔ ÙÔÓ ·ÛıÂÓ‹, ›Ù Â› 24ˆÚ˘ ‚¿Û˘ (Û˘Ó¯›˜ ‰˘Ó¿ÌÂȘ), ›Ù ÁÈ· 12 ÒÚ˜ ÙÔ 24ˆÚÔ (‰È·ÎÔÙfiÌÂÓ˜ ‰˘Ó¿ÌÂȘ). ª ª¤¤ÁÁÂÂııÔÔ˜˜ ÔÔÚÚııÔÔ‰‰ÔÔÓÓÙÙÈÈÎÎÒÒÓÓ ‰‰˘˘ÓÓ¿¿Ì̈ˆÓÓ ∆ÂÎÌËÚȈ̤ÓË ·¿ÓÙËÛË Û¯ÂÙÈο Ì ÙËÓ ÂÈÏÔÁ‹ ¯Ú‹Û˘ ‹ÈˆÓ ‹ ÈÛ¯˘ÚÒÓ ‰˘Ó¿ÌˆÓ, Ê·›ÓÂÙ·È fiÙÈ Û‡Ìʈӷ ÙÔ˘-Ï¿¯ÈÛÙÔÓ Ì ٷ ˘¿Ú¯ÔÓÙ· ÂÚÂ�