Complications During Surgical Insertion of Miniimplants

Editorial

anna Znamirowska-Bajowska, tomasz ogiński, Janina Szeląg

Complications During Surgical Insertion

of Miniimplants

Powikłania podczas umieszczania miniimplantów

department of Facial abnormalities, department of Maxillofacial orthopedics and orthodontics, Wroclaw Medical University, Poland

Abstract

Miniscrews have been introduced as a temporary cortical anchorage device in orthodontic treatment. despite all the advantages, miniscrews are burdened by some complications. treatment with miniimplants can fail for vari-ous reasons, including improper surgical techniques during placement.the possibilty complication during surgi-cal insertion are: dental root, blood vessels and nerves injuries, perforation of maxillary sinus and nasal cavity, miniimplant instability and fracture, slippage. Fortunately, proper proceeding during implantation may reduce or even eliminate potential complication. the aim of this article was to consider complications that occur during the insertion of miniimplants (Dent. Med. Probl. 2011, 48, 1, 11–18).

Key words: orthodontic miniimplants, implantation, complications.

Streszczenie

Miniśruby zostały wprowadzone w leczeniu ortodontycznym jako środek do otrzymania tymczasowego zako-twienia kortykalnego. Mimo ich wszystkich zalet, miniśruby są również obciążone pewnymi wadami. leczenie z użyciem miniimplantów może się nie powieść z wielu powodów, włączając w to niewłaściwą technikę chirurgicz-nej implantacji. Możliwe powikłania podczas umieszczania miniimplantów to: zranienie korzenia, naczyń krwio-nośnych i nerwów, perforacja zatoki szczękowej i jamy nosowej, niestabilność pierwotna, złamanie i „poślizg” miniimplantu. Właściwa procedura postępowania w czasie zabiegu pozwala zmniejszyć lub nawet wyeliminować wystąpienie powikłań. Celem pracy było omówienie możliwych powikłań, jakie mogą pojawić się podczas umiesz-czania miniimplantów (Dent. Med. Probl. 2011, 48, 1, 11–18).

Słowa kluczowe: miniimplanty ortodontyczne, implantacja, powikłania.

dent. Med. Probl. 2011, 48, 1, 11–18

iSSN 1644-387X © Copyright by Wroclaw Medical University and Polish dental Society

For many years methods of maximum chorage to prevent undesirable movement of an-chorage teeth have been searched. anan-chorage is a critical and important issue in successful orth-odontic treatment [1]. Commonly used methods do not eliminate the movement of the anchoring teeth, may cause some side effects and therapeu-tic succses is often dependent on cooperation with the patient. in 1997 Kanomi [2] described mini-implants – titanic screws designed for orthodontic purpose. Since that time miniscrews have been in-troduced as a temporary cortical anchorage device (tCad) in orthodontic treatment – intraoral, ex-tradental and indirect anchorage. the term tCad describes all sorts of screws, implants, pins, posts

and onplants used to provide skeletal anchorage and removed after ending of therapy and usually made of titanium alloy [3]. in contradiction to the prosthetic implants, osseointegration of orthodon-tic miniscrews is undesirable.

tCads enable corrections of vertical (eg. intrusion of incisors in deep bite malocclusion or molar intrusion in open bite malocclusion) and anterio−posterior positions (eg. protraction of posterior teeth, retraction of anterior teeth or molars distalization in class ii malocclusion) of teeth [4]. Miniscrews are also inserted whenever dental displacements are essential and the orth-odontic therapy based on miniimplants can pre-cede prosthodotic therapy.

there are two types of miniimplants [5]. Self- -tapping ones are inserted into a guide-hole, which is made by a drill bit (pre-drilling method). Self-drilling ones, used in the drill-free metod, are in-serted directly into the intact cortical bone [6].

they have a lot of advantages such as: small size, versatility, no need for laboratory work, pos-sibility of immediate loading, easy insertion and removal, independence on patient’s cooperation, treatment time reduction, patient’s comfort and relatively low cost [6–10]. despite all the advan-tages miniscrews are burdened by some compli-cations. treatment with miniimplants can fail for various reasons including improper surgical techniques during placement [11]. the aim of this article was to consider complications that occur during the insertion of miniimplants.

Systemic Complications

Surgical technique of the tCad is simple and requires only a local anesthetsia. Most complica-tions that may occur during any surgical proce-dure are minor. occasionally, systemic complica-tion may occur which can lead to life-threatening situations [12]. these medical emergencies such as cardiac or respiratory arrest are usually unex-epected and rare. despite this, every doctor should know and follow basic life support skills. in order to avoid complications and undergo an effective treatment with miniscrew, every patient should be questioned on their medical and dental his-tory. detailed information should be obtained on respiratory and cardiac diseases, diabetes, current and past drugs intake (including steroids, anti- -coagulants), pregnancy, drug allergies, excessive bleeding after injuries, previous general and local anaesthetic experience.

theoretically, during placing of a miniscrew into the palate, the miniscrew may be accidentally swallowed or inhaled. this situation may occur due to a sudden movement (especially at nervous patient or in case of inadequate depth of anesthe-sia), especially without adequate airway protec-tion. this may cause the need for gastroscopic or bronchoscopic removal of a foreign body.

Dental Root Injury

Miniscrews are usually placed interradicular-ly. improper placement of miniscrew runs a risk of accidental injury of the dental root and perio-dontium or bone damage. Sometimes root wound-ing provides loss of tooth vitality, root resorption, dentoalveolar ankylosis or osteosclerosis [13–16].

Healing of the periodontal structure is possible when the root injury is limited to the cementum or the dentin [14–15].

Histological examination showed an almost complete repair of periodontal ligament, cemen-tum and bone in 12 weeks after removal of the miniimplant [15]. Under unfavorable conditions (such as pulpal invasion or inflammatory infil-tration), regeneration of the damaged attachment apparatus and healing proces is interrupted [14]. Cheng et al. [17] suggested that the risk of infection significantly increases when screws are placed into the alveolar mucosa. invasion of the pulp chamber allows access of the pathogens which may lead to the root resorption, bone destruction and tooth de-vitalization. this situation can require extraction if endodontic treatment of the injured tooth fails [14]. Some orthodontists recommended manual inser-tion for a good tactile control [18] and possibility to sense when the implant touches the root. if during manual insertion clinician notices increase in resis-tance, he should back out and redirect the implant [19]. Position after insertion may be controlled by radiographic examination – periapical radiograms in two oblique and one perpendicular projections [20]. Unfortunately, errors and distortions in par-allel technique of radiograms could produce “false negative” and “falce positieve” pictures.

Various recommendations are suggested for tCad placement to protect surrounding struc-tures, from 1.0 mm between the periodontal ligament and the miniimplants, 2.5 mm of bone around the tCad, to 5.0 mm between adjacent roots of tCad. to allow displacement up to 1.5 mm of miniscrew during loading liou et al suggested minimal distance of 2.0 mm between the root and the tCad [13].

there are also general guidelines – a map of safe zones – during the placement of miniscrew but they do not include individual differences in ana-tomical structures and root morphology [21–22]. Kyung-Seok et al. [23] recommend the safest area for miniscrew placement as space between second premolar and first molar 6–8 mm above the cer-vical line in the maxilla and between a first and second molar, less than 5 mm from the cervical line in the mandible.

Perforation of Maxillary

Sinus and Nasal Cavity

Perforation of a maxillary sinus is a rare com-plication during placement of tCads. Maxil-lary sinus floor elevation anteriorly extends to the canine and premolar area. the apices of the molars and premolars can penetrate or touch this

floor [24]. the perforation of maxillary sinuses is possible during miniimplant placement in the zy-gomatic and maxillary posterior dentoalveolar re-gions. the major predispositions of this complica-tion are: posterior maxillary atrophy [25–26], a very high screw placement [19, 27], sinus size increasing with age if the alveolar is edentulous [28], increased sinus pneumatization [29], increased miniimplant length, extrusion of the maxillary molar [30]. late symptoms of the sinus perforation may be post-operative maxillary sinusitis or creation of chronic oroantral fistula [31]. the likelihood of their devel-opment is largely dependent on the size of the co-munication. Small communications (2 mm or less) heal by themselves and require only routine post-operative observation [32–33]. Fortunately, most current miniimplants diameters do not exceed 2 mm, therefore the chance of these complications is small and does not affect miniimplant stability [34]. therefore, in the case of this complication miniscrew does not require removal if the sinus is asymptomatic [31] and orthodontic treatment can be continued. Planning for anchoring in the maxillary incisal region and along the midpalatal suture carries the potential risk of perforation of the nasal cavity [35–36]. the implant is not placed directly into the midpalatal suture which can con-sist of connective tissue, but in paramedian region (the lateral side of the palatal suture). to reduce the risk of perforation, miniscrews should be placed on the palate mesially to the second molar [25]. in the posterior edentulous maxilla and anterior maxillary region, the clinician should consider the angle of insertion approximately 90 degrees to the occlusal plane during placement, parallel to the paranasal sinus floor [31]. Kang et al. [36] made maps of mean palatal bone thickness for selection of the miniscrew lenght and for visual comparison of placement locations. they recommended com-putered tomographic images for safety beacause of individual variation in bone thickness and sig-nificant differences between the male and female groups. the thickest bone is available in the area of 1 mm of the midline, in the posterior palate. the thickness tended to decrease posteriorly and later-ally. they recommend to use shorter miniscrew in case if miniscrew could deviate more than 1 mm from the midpalatal area. in that case miniscrew should be placed not far posteriorly.

Blood Vessels

and Nerves Injuries

also blood vessels and nerves can be injured during the miniscrew placement. those occur rare, as vessels and nerves generally lie away from

insertion sites [37]. an ideal implant position is in a non-tooth-bearing site, without any pathway or foramen of major blood vessels and nerves [27]. in-creased care should be taken in particular regions on the palatal slope such as the pathways of the nervus palatinus major, the arteria palatina major and nervus incisivus. also the retromolar region, the retromolar pad and buccal dentoalveolus in the mandible, places where the nervus and arteria alveolaris inferior, the nervus and arteria mentalis, the long buccal nerve and the lingual nerve are lo-calized, should be embraced as particular regions of nerves and blood vessels injury [38]. the tough-est bone and specific shape of the mandible in the retromolar area require much attention during implantation to prevent injury to the mandibular canal which is close to this area and the lingual nerve travels on the inner side of the ramus.

it is preferable that implantation and surgical extraction of an impacted third molar are per-formed together. Flap surgery increase visability and accessibility of the retromolar area. Predrill-ing bone can reduce the risk of miniscrew fracture and surgical trauma.

Placement of tCads in the palatal slope risk potential damage of the greater palatine nerve and the greater palatine artery. to minimalize this miniscrews should be inserted mesially to the sec-ond molar in the palatal slope [25, 31, 39].

Nerve injury may result in parasthesia, dys-ethesia, anesthesia or combination of the symp-toms. Usually, nerve damage heals spontaneously without medications, with gradual regeneration of sensation in several weeks or even months. But if the symptoms do not diminish in 8 weeks, patients require pharmacotherapy: B group vi-tamins, NSaid, corticosteroids, antihistamine, vasodilatators, diuretics, laser therapy or in same cases micronerosurgery with the nerve decompre-sion and grafting [40–41].

to avoid this complication various methods have been attempted, among which are proper radiographic planning and placement technique and localization of miniscrews. investigations al-lowed to create special anatomical maps to deter-mine safer locations and control insertion angle [42–43]. the literature advises to use radiographic examination before microscrew anchorage, which provides a topographical survey of the anatomi-cal structures. the most common techniques are panoramic and periapical dental radiographs. or-thopantomography provides information about bone quality and density, root angulation and localisation of vessels, nerves, sinus spaces, and dental germs in growing patients [42]. Same or-thodontist recommended using computed tomog-raphy before insertion to show all structures for

the three space levels [21]. it is suggested to use a surgical guide when miniscrews are placed near delicate anatomical structures such nerve, sinus or root to precisely locate the vector and the place-ment point [44].

Miniimplant Instability

and Fracture

Primary stability is the screw’s initial anchor-age in the bone. it is essential, as orthodontic miniscrews are loaded immediately after the in-sertion [45]. the factors that influence primary stability are: insertion modalities, bone quality and implant design. lack of primary stability usu-ally leads to progressive miniscrew mobility and failure [46–47]. High insertion torque has been attributed to high primary stability of miniim-plant [48]. a smaller pilot hole diameter may in-crease insertion torque but also may lead to screw fracture [49]. to achieve maximum primary stabil-ity and minimize the possibilstabil-ity of screw fracture, the ideal size of pilot drilling should be consid-ered carefully and individually to each screw type. the diameter of a pilot hole should be adequate to the screw’s diameter and length and the bone’s quality. it is recommended that the diameter of the pre-drill hole is 80% of the screw diameter or match the thread’s internal diameter [50]. it is also believed that other screw factors such as diameter, lenght, screw thread form are also important for initial stability [51].

Florvaag et al. reported that initial stability improved after drill-free method [47]. Miniscrew stability can be affected also by microcracks in the bone formed during the placement as a result of increased torsional stress. Self-drilling tCad, larger diameter and conical or tapered shape might cause overcompression by excessive torque. this can lead to microdamage to the cortical bone [47, 52]. tads placed at a higher torque may pro-duce high stress, therefore to achieve higher suc-cess, a lower implant placement torque (5–10 Ncm) is suggested [56]. it is belived that the majority of primary stability of tCads comes from cortical bone, with lesser degree by medullary bone[54]. “High angle” patients tended to have thinner buc-cal cortibuc-cal bone. in this case or when the place of insertion has inadequate amount of compact bone, it is reccomended to use a bigger miniimplant [55]. another reason for inadequate primary stabil-ity are pilot hole overenlargement and pilot drill overheating [56]. the main reason for too large predrilled passageway is the orthodontist’s inabil-ity to hold the handpiece stable and keep a drill in one and same plane without lateral movement

during drilling. if primary mobility is present at the time of placement, then relocation should be considered immediately.

the miniimplants should exhibit biocompat-ibility, excellent corrosion resistance and mechani-cal strength. Mechanimechani-cal strength must be enough to resist torsinal stresses developed during place-ment and removal. despite the developplace-ment of technologies and rising experience with miniscrew treatment, fracture of miniscrew implants during placement or removal may occur [57]. it seems that this is largely related to the morphologic design of the implant [58] and the strength of titanium or a titanium alloy, which depends on its microstruc-ture. Microstructure is influenced by the machin-ing process of the miniimplants, heat treatment and composition [58]. Screws with a smaller diam-eter are easier to inserted between the roots. Unfor-tunately a small decrease in diameter significantly increases the torsional strength and the risk of fracture especially in the thick cortical bone of the mandible [10]. Park et al. [38] in order to minimize the risk of fracture recommends use of screws with a diameter of 2 mm or more and a steady implan-tation technique. others have argued that in order to avoid this complication a pilot hole should be made in dense cortical bone, even for self-drilling miniscrews and placed slowly and with minimal pressure [59]. a smaller pilot hole diameter may be used to increase insertion torque, thus improving primary stability but may cause of screw fracture. to achieve maximum primary stability and mini-mize the risk of fracture, this dimension should be considered individually to each screw type [47]. also the long mini-implant may provide higher stability but they may break due to high insertion torque [64]. in the case of miniscrew fracture at the level of the bone, it may be advisable to leave the screw in place. the orthodontist should place a new miniscrew in the site adjacent to the frac-tured minimplant. after the surgery postoperative radiograph is performed [29].

Other Complications

there are same areas of increased cortical bone thickness and density. the densed structure of the bone with heavy forces during implantation lead to problems during initial insertion, because of slipping miniscrew along the periosteum [30]. Critical regions include the buccal cortical shelf, the zygomatic buttress, the retromolar pad, man-dibular buccal alveolar region, the maxillary buccal exostosis. in this cases even placing a self- -driling tCad may require pre-drilling. Some cli-nicians make a pit perpendicularly in the cortical

bone with a small round or fissure bur before us-ing pilot drillus-ing. the others begin insertion at an obtuse angle to create a purchase point with the tip of the tCad. then, after tCad reach the cortical bone steepen the angle to complete the insertion [31, 61]. Steeper angulation (< 30 degree) increases the risk of slippage but minimizes the risk of root injury [31].

Fibrous capsulation of the screw, bone necro-sis and implant failure may be caused by excessive surgical trauma and thermal injury [62]. Self-drill-ing miniscrews have cuttSelf-drill-ing flutes at the tip to cut bone that allows screw to enter the bone. Some or-thodontists made also a pit perpendicular in corti-cal plate using round burs before insertion. these procedures should be done with saline cooling [3] and judicious care to prevent the bone from over-heating, because most of the energy is not used in the cutting process but it is transformed into heat. a temperature over 47 degree only for more than 1 minute leads to bone necrosis [63]. the amount of friction is dependent on the thickness and den-sity of the cortical plate where the tCad must be placed. in the mandibule, where this layer is thick-er and more dense than in maxilla, more fiction and heat are created [11].

Sometimes miniscrew is needed to be inserted in the place covered by unattached gingiva. in this case a tissue punch or cutting off the mucosa and periosteum should be performed, because of ten-dency to wind around the pillot drill or the body of miniscrew which causes soft tissue injury and trauma [64].

Subcutaneous emphysema arises from the introduction of air or other gases into softs tis-sues [65]. it is caused by high pressure air instru-ments, air-water syringes, air-driven, high-speed handpieces or spray or jet devices [66–67]. Gas-eous invasion may be restricted to the connective tissues immediately adjacent to the entry site, but passage and accumulation of air between tissue spaces or fascial planes may also lead to tissue-space emphysema [68]. the specific symptoms are: immediate mucosal swelling with crepi-tus [69], the absence of erythema, which appears in a few seconds or minutes after air has entered the submucosal space significant tenderness, or lymphadenopathy edema [68]. additionally pa-tient may also experience other symptoms such as mild discomfort, cervicofacial and orbital swelling, airway obstruction with difficulty in breathing, ear pain, hearing loss, interproximal and interseptal alveolar necrosis [70], intense

dysphonia (whispering and husky voice) [68], optic nerve damage [67], sometimes pain caused by tension present in tissues [71]. the differen-tial diagnosis should consider allergic reaction, angioedema, hematoma and infection. during a sudden swelling an allergic reaction should be considered [67]. to avoid these unpleasant com-plications, implantation should be made with a slow-speed and low-pressure, for both drilling a pilot hole through the mucosa and purchasing a point. Excessive bleeding and salivation should be removed with a sterile gauze or a suction. Par-ticular care should be taken when placing im-plants in the deep gum pockets [65], and several regions: maxillary zygomatic, buccal mandibular posterior and retromolar one. By the time swell-ing appears, all performed procedures should be discontinued. depending on the area, the suitable X-rays are taken: periapical, pantomo graphic, head and neck, in order to confirm the diagno-sis and determine extent of the changes [65]. in cases of mild to moderate emphysema treatment is limited to reinsurance and observation of the patient [72]. to prevent secondary infections pro-phylactic administration of antibiotics is recom-mended (preferentially amoxicillin with clavu-lanic acid) [73]. after 5 to 10 days the majority of patients resolve spontaneously. However, in some cases, emphysema may lead to the development of symptoms of potentially life-threatening [65]. Patient should not perform activities that in-crease the intraoral pressure, such as blowing nose or playing musical instruments [74]. the literature describes subcutaneous emphysema, pneumomediastinum, pneumopericardium, and pneumothorax as complications following dental procedures [75]. in case of thorax and back pain a thorax X-ray should be also performed [76].

tCads are very helpful in obtaining anchor-age especially in non-compliance patients. With the possibility of therapeutic gain increasing recognition and use throughout the world, often solving therapeutic problems, which hitherto have been the cause of failures in treatment. despite the multitude of possible complications, they rarely occur and produce permanent, irreversible dam-age or health problems. the surgical technique is simple and does not require the use of multiple tools. through clinical and experimental trials, technique and mechanical properties of miniim-plants are continuously improved. Proper pro-ceeding during implantation may reduce or even eliminate potential complication.

References

[1] Chen Y.J., Chang H.H., Huang C.Y., Hung H.C., lai E.H., Yao C.C.: a retrospective analysis of the failure rate of three different orthodontic skeletal anchorage systems. Clin. oral implants res. 2007, 18, 768–775.

[2] Kanomi r.: Mini-implant for orthodontic anchorage. J. Clin. orthod. 1997, 11, 763–767.

[3] Mah J., Bergstrand F.: temporary anchorage devices: a status report. J. Clin. orthod. 2005, 39, 132–136. [4] raftowicz-Wójcik K., antoszewska J., Kawala B.: leczenie nieekstrakcyjne klasy ii/1 z zastosowaniem

zam-ków samoligaturujących Quick oraz miniimplantów ortodontycznych – opis przypadku. dent. Med. Probl. 2009, 46, 365–370.

[5] Baumgaertel S., razavi M.r., Hans M.G.: Mini-implant anchorage for the orthodontic practitioner. am. J. orthod. dentofacial orthop. 2008, 133, 621–627.

[6] Wang Y.C., liou E.J.W.: Comparison of the loading behavior of self-drilling and predrilled mini-screws thro-ughout orthodontic loading. am. J. orthod. dentofacial orthop. 2008, 133, 38–43.

[7] tseng Y.C., Hseh C.H., Chen C.H., Shen Y.S., Huang i.Y., Chen C.M.: the application of mini-implants for orthodontic anchorage. int. J. oral Maxillofac. Surg. 200, 35, 704–707.

[8] Cetinsahin a., arman a.: application of implants for orthodontic anchorage. turk. orthodont. derg. 2005, 18, 77–89.

[9] Wilmes B., drescher d.: a miniscrew system with interchangeable abutments. J. Clin. orthod. 2008, 42, 574–580. [10] reynders r., ronchi l., Bipat S.: Mini-implants in orthodontics: a systematic review of the literature. am. J. orthod.

dentofacial orthop. 2009, 135, 564, e1–564, e19.

[11] Park H.S., Jeong S.H., Kwon o.W.: Factors affecting the clinical success of screw implants used as orthodontic anchorage. am. J. orthod. dentofacial orthop. 2006, 130, 18–25.

[12] avoiding complications in minor oral surgery. in: Maxillofacial Surgery Eds.: Ward-Booth P., Hausaman J-E., Schendel S., Churchill livingstone, Edinburgh 1999, 1591–1610.

[13] Hembree M., Buschang P.H., Carrillo r., Spears r., rossouw P.E.: Effects of intentional damage to the roots and surrounding structures with miniscrew implants. am. J. orthod. dentofacial orthop. 2009, 135, 280.e1–280.e9. [14] Briceno C., Buschang P., Carrillo r., Spears r.: Healing of the root and surrounding structures after

inten-tional damage with a miniscrew implant. am. J. orthod. dentofacial orthop. 2009, 135, 292–301.

[15] asscherickx K., Vannet B.V., Wehrbein H., Sabzevar M.M.: root repair after injury from miniscrew. Clin. oral implants res. 2005, 16, 575–578.

[16] Kuroda S., Yamada K., deguchi t., Hashimoto t., Kyung H.M., takano-Yamamoto t.: root proximity is a major factor for screw failure in orthodontic anchorage. am. J. orthod. dentofacial orthop. 2007, 131, 68–73. [17] Cheng S.J., tseng i.Y., lee J.J., Kok S.H.: a prospective study of the risk factors associated with failure of

mini-implants used for orthodontic anchorage. int. J. oral Maxillofac. mini-implants. 2004, 19 100–106. [18] Melsen B.: Mini-implants? Where are we? J. Clin. orthod. 2005, 39, 539–547.

[19] Carano a., Velo S., incorvati C., Poggio P.: Clinical applications of the mini-screw-anchorage-system (M.a.S.) in the maxillary alveolar bone. Prog. orthod. 2004, 5, 212–235.

[20] antoszewska J., Kawala B., Sarul M.: Factors affecting stability of orthodontic implants. a Wroclaw method. Forum ortodont. 2010, 6, 1, 5–14.

[21] Poggio P.M., incorvati C., Velo S., Carano a.: ‘‘Safe zones’’: a guide for miniscrew positioning in the maxillary and mandibular arch. angle orthod. 2006, 76, 191–197.

[22] ishii t., Nojima K., Nishii Y., takaki t., Yamaguchi H.: Evaluation of the implantation position of mini-screws for orthodontic treatment in the maxillary molar area by a micro Ct. Bull. tokyo dent. Coll 2004, 45, 165–172. [23] Hu K.S., Kang M.K., Kim t.W., Kim K.H., Kim H.J.: relationships between dental roots and surrounding tissues

for orthodontic miniscrew installation. angle orthod. 2009, 79, 37–45.

[24] testori t., del Fabbro M.: anathomy of the maxillary sinus. in: Maxillary sinus surgery and alternatives in treat-ment. Eds.: testori t., Wallace S., del Fabbro M., Weinstein r., Quintessence Publishing, london 2009, 7–22. [25] tamamura N., Kuroda S., Sugawara Y., takano-Yamamoto t., Yamashiro t.: Use of palatal miniscrew

anchorage and lingual multi-bracket appliances to enhance efficiency of molar scissors-bite correction. angle orthod. 2009, 79, 577–584.

[26] Calvo-Guirado J.l., Saez-Yuguero r., Pardo-Zamora G.: Compressive osteotomes for expansion and maxilla sinus floor lifting. Med. oral Patol. oral Cir. Bucal. 2006, 11, 52–55.

[27] liou E.J.W., Pai B.C.J., lin J.C.Y.: do miniscrews remain stationary under orthodontic forces? am. J. orthod. dentofacial orthop. 2004, 126, 42–47.

[28] Woo i., le B.t.: Maxillary sinus floor elevation: review of anatomy and two techniques. impl. dent. 2004, 13, 28–32. [29] Graham J., Cope J.: Miniscrew troubleshooting. orthod. Products 2006, 4–5, 26–32.

[30] Park C.H., Park i.K., Woo Y., Kim t.W.: Complications and their management. in: orthodontic Miniscrew implants: Clinical applications. Mosby 2008, 245–254.

[31] Kravitz N.d., Kusnoto B., tsay t.P., Hohlt W.F.: the use of temporary anchorage devices for molar intrusion. J. am. dent. assoc. 2007, 138, 56–64.

[32] reiser G.M., rabinovitz Z., Bruno J., damoulis P.d., Griffin t.J.: Evaluation of maxillary sinus membrane response following elevation with the crestal osteotome technique in human cadavers. int. J. oral Maxillofac. implants. 2001, 16, 833–840.

[33] ardekian l., oved-Peleg E., Mactei E.E., Peled M.: the clinical significance of sinus membrane perforation during augmentation of the maxillary sinus. J. oral Maxillofac. Surg. 2006, 64, 277–282.

[34] Sugawara J., Baik U.B., Umemori M., Nagasaka H., Kawamura H., Mitani H.: treatment of posttreatment dentoalveolar changes following intrusion of mandibular molars with application of a skeletal anchorage system (SaS) for open bite correction. int. J. adult orthodon. orthognath. Surg. 2002, 17, 243–253.

[35] Keles a., Erverdi N., Sezen S.: Bodily distalization of molars with absolute anchorage. angle orthod. 2003, 73, 471–482.

[36] Kang S., lee S.J., ahn S.J., Heo M.S., Kimd t.W.: Bone thickness of the palate for orthodontic mini-implant anchorage in adult. am. J. orthod. dentofacial orthop. 2007, 131, 4, Supll., 74–81.

[37] lombardoa l., Graccoa a., Zampinib F., Stefanonic F., Mollicad F.: optimal palatal configuration for mini-screw applications. angle orthod. 2010, 80, 145–152.

[38] Park Y.C., lee S.Y., Kim d.H., Jee S.H.: intrusion of posterior teeth using mini-screw implants. am. J. orthod. dentofacial orthop. 2003, 12, 690–694.

[39] al-Fraidi a.a., Zawawi K.W.: Selective intrusion of overerupted upper first molars using a temporary anchorage device: case report. J. Can. dent. assoc. 2010, 76, a9.

[40] Kubilius r., Sabalys G., Juodzbalys G., Gedrimas V.: traumatic damage to the inferior alveolar nerve susta-ined in course of dental implantation. Possibility of prevention. Stomatologija 2004, 6, 106–110.

[41] Smith M.H., lung K.E.: Nerve injuries after dental injection: a review of the literature. J. Can. dent. assoc. 2006, 72, 559–564.

[42] Hernandez l.C., Montoto G., Puente rodrıguez M., Galban l, Martınez V.: ‘‘Bone map’’ for a safe place-ment of miniscrews generated by computed tomography. Clin. oral implants res. 2008, 19, 576–581.

[43] Cho U.H., Yu W., Kyung H.M.: root contact during drilling for microimplant placement. affect of surgery site and operator expertise. angle orthod. 2010, 81, 130–136.

[44] Kim S.H., Choi Y.S., Hwang E.H., Chung K.r., Kook Y.a., Nelson G.: Surgical positioning of orthodontic mini-implants with guides fabricated on models replicated with cone-beam computed tomography. am. J. orthod. dentofac. orthop. 2007, 131, 82–89.

[45] Melsen B., Costa a.: immediate loading of implants used for orthodontic anchorage. Clin. orthod. res. 2000, 3, 23–28.

[46] Mischkowski r.a., Kneuertz P., Florvaag B., lazar F., Koebke J., Zöller J.E.: Biomechanical comparison of four different miniscrew types for skeletal anchorage in the mandibulo-maxillary area. int. J. oral Maxillofac. Surg. 2008, 37, 948–954.

[47] Florvaag B., Kneuertz P., lazar F., Koebke J., Zöller J.E., Braumann B., Mischkowski r.a.: Biomechanical properties of orthodontic miniscrews. an in vitro study. J. orofac. orthop. 2010, 71, 53–67.

[48] Wilmes B., rademacher C., olthoff G., drescher d.: Parameters affecting primary stability of orthodontic miniimplants. J. orofac. orthop. 2006, 67, 162–174.

[49] Sakoh J., Wahlmann U., Stender E., Nat r., al-Nawas B., Wagner W.: Primary stability of a conical implant and a hybrid, cylindric screw-type implant in vitro. int. J. oral Maxillofac. implants. 2006, 21, 560–566.

[50] Gantous a., Philipps J.H.: the effects of varying pilot hole size on the holding power of miniscrews and micro-screws. Plast. reconstr. Surg. 1995, 95, 1165–1169.

[51] lim S., Cha J., Hwang C.: insertion torque of orthodontic miniscrews according to changes in shape, diameter and length. angle orthod. 2008, 78, 234–240.

[52] lee N.K., Baek S.H.: Effects of the diameter and shape of orthodontic mini-implants on microdamage to the cor-tical bone. am. J. orthod. dentofacial orthop. 2010, 138, 1, 8.e1–8.e8.

[53] Motoyoshi M., Hirabayashi M., Uemura M., Shimizu N.: recommended placement torque when tightening an orthodontic mini-implant. Clin. oral implants res. 2006, 17, 109–114.

[54] dalstra M., Cattaneo P.M., Melsen B.: load transfer of miniscrews for orthodontic anchorage. orthod. 2004, 1, 53–62.

[55] Miyawaki S., Koyama i., inoue M., Mishima K., Sugahara t., takano-Yamamoto t.: Factors associated with the stability of titanium screws placed in the posterior region for orthodontic anchorage. am. J. orthod. dentofacial orthop. 2003, 124, 373–378.

[56] Heidemann W., terheyden H., Gerlach K.l.: analysis of the osseous metal interface of drill free screws and self-tapping screws. J. Craniomaxillofac. Surg. 2001, 29, 69–74.

[57] Buchter a., Wiechmann d., Koerdt S., Wiesmann H.P., Piffko J., Meyer U.: load-related implant reaction of mini-implants used for orthodontic anchorage. Clin. oral implants res. 2005, 16, 473–479.

[58] iijima M., Muguruma t., Brantley W.a., okayama M., Yuasa t., Mizoguchid i.: torsional properties and microstructures of miniscrew implants. am. J. orthod. dentofacial orthop. 2008, 134, 333.e1–333.e6.

[59] Kravitz N.d., Kusnoto B.: risks and complications of orthodontic miniscrews. am. J. orthod. dentofacial orthop. 2007, 131, S43–51.

[60] Holmgren E.P., Seckinger r.J., Kilgren l.M., Mante F.: Evaluating parameters of osseointegrated dental implants using finite element analysis: a two-dimensional comparative study examining the effects of implant diameter, implant shape, and load direction. J. oral implantol. 1998, 24, 80–88.

[61] Kravitz N.d.: Placing tads. orthod. Products 2009, 8, 112–118.

[62] albrektsson t., Eriksson r.: thermally induced bone necrosis in rabbits: relation to implant failure in humans. Clin. orthop. 1985, 195, 311–312.

[63] Eriksson r.a., albrektsson t.: the effect of heat on bone regeneration: an experimental study in the rabbit using the bone growth chamber. J. oral Maxillafac. Surg. 1984, 42, 705–711.

[64] Hoste S., Vercruyssen M., Quirynen M., Willems G.: risk factors and indications of orthodontic temporary anchorage devices: a literature review. aust. orthod. J. 2008, 24, 140–148.

[65] Gamboa-Vidal C.a., Vega-Pizarro C.a., almeida-arriagada a.: Subcutaneous emphysema secondary to dental treatment: Case report. Med. oral Patol. oral Cir. Bucal. 2007, 12, 76–78.

[66] Nates J.l., Gertel M.: Subcutaneous and mediastinal emphysema during dental treatment under general ane-sthesia. internet J. anesthesiol. 2000, 4, 1–9.

[67] Buckley M.J., turvey t.a., Schumann S.P., Grimson B.S.: orbital emphysema causing vision loss after a dental extraction. J. am. dent. assoc. 1990, 120, 421–422.

[68] Frühauf J., Weinke r., Pilger U., Kerl H., Müllegger r.r.: Soft tissue cervicofacial emphysema after dental treatment. arch. dermatol. 2005, 41, 1437–1440.

[69] Hülsmann M., Hahn W.: Complications during root canal irrigation – literature review and case reports. int. Endod. J. 2000, 33, 186–193.

[70] Schuman N.J., owens B.M., Shelton J.t.: Subcutaneous emphysema after restorative dental treatment. Compend. Contin. Educ. dent. 2001, 22, 38–40, 42.

[71] Guest P.G., Henderson S.: Surgical emphysema of the mediastinum as a consequence of attempted extraction of a third molar tooth using an air turbine drill. Br. dent. J. 1991, 171, 283–284.

[72] Karras S.C., Sexton J.J.: Cervicofacial and mediastinal emphysema as the result of a dental procedure. J. Emerg. Med. 1996, 14, 9–13.

[73] Feinstone t.: infected subcutaneous emphysema: report of case. J. am. dent. assoc. 1971, 83, 1309–1311. [74] ali a., Cunliffe d.r., Watt-Smith S.r.: Surgical emphysema and pneumomediastinum complcating dental

extraction. Br. dent. J. 2000, 188, 589–590.

[75] Sandler C.M., libshitz H.i., Marks G.: Pneumoperitoneum, pneumomediastinum, and pneumopericardium following dental extraction. radiol. 1975, 115, 539–540.

[76] reznick J.B., ardary W.C.: Cervicofacial subcutaneous air emphysema after dental extraction. J. am. dent. assoc. 1990, 120, 417–419.

Address for correspondence:

department of Maxillofacial orthopedics and orthodontics Wroclaw Medical University

Krakowska 26 50-425 Wrocław Poland tel.: +48 71 784 02 99 E-mail: aznamirowska.b@gmail.com received: 6.10.2010 revised: 10.01.2011 accepted: 23.02.2011

Praca wpłynęła do redakcji: 6.10.2010 r. Po recenzji: 10.01.2011 r.