prosthetic considerations for orthodontic implant site development

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    Oral Maxillofac Surg7:82-88, 2009, Suppl 3

    Prosthetic Considerations forOrthodontic Implant Site Development in

    the Adult PatientAlexandra I. Holst, DMD,* Emeka Nkenke, MD, DDS, PhD,

    Markus B. Blatz, DMD, PhD, Hans Geiselhringer, CDT, MDT,

    and Stefan Holst, DMD, PhD

    Proper site development is a key factor for long-term clinical success of dental implants. Whereas surgicaland restorative techniques have been refined to ensure predictable functional and esthetic outcome,individual clinical prerequisites do not always allow proper placement of implants when prosthetic andmaterial properties are considered. Orthodontic tooth movement may be a viable and nonsurgical sitedevelopment treatment option. With the introduction and advancements of minimal invasive and lessvisible orthodontic appliances, a growing number of adult patients are willing to obtain orthodontictreatment. The spectrum of modern appliances is broad and ranges from clear aligners to lingualbrackets. Skeletal anchorage devices such as orthodontic mini-implants often eliminate unpopularexternal anchorage devices (ie, headgear) in adult patients, This article discusses the selection of anappropriate pretreatment approach by taking patient-specific criteria into account. 2009 American Association of Oral and Maxillofacial Surgeons

    J Oral Maxillofac Surg 67:82-88, 2009, Suppl 3

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    lthough replacing missing single teeth with dentalmplants has become routine, in many cases the initiallinical situation does not provide for optimal implantositioning. Especially in adult patients with missingeeth, neighboring or opposing teeth may migrate,

    *Associate Professor, University Clinic Erlangen, Dental Clinic 3,

    epartment of Prosthodontics, Erlangen, Germany.

    Associate Professor, University Clinic Erlangen, Department of

    ral and Maxillofacial Surgery, Erlangen, Germany.

    Professor of Restorative Dentistry, Chairman, Department of Pre-

    entive and Restorative Sciences, Robert Schattner Center, University

    f Pennsylvania, School of Dental Medicine, Philadelphia, PA.

    Dental X Hans Geiselhringer GmbH & Co, Munich, Germany.

    Associate Professor, University Clinic Erlangen, Dental Clinic 2,

    epartment of Prosthodontics, Erlangen, Germany.

    Drs Alexandra I. Holst and Emeka Nkenke state no financial ar-

    angement or affiliation with a corporate organization or a manufac-

    urer of a product discussed in this article. Dr Stefan Holst has received

    onoraria from Nobel Biocare. Dr Markus B. Blatz has received re-

    earch contracts and/or grants from Nobel Biocare, Ekton/Straumann,

    eraeus Kulzer, 3M ESPE, Noritake, Kuraray, Coltene Whaledent, and

    voclar Vivadent. Dr Hans Geiselhringer has received governance and

    aid consultantship from Nobel Biocare.

    Address correspondence and reprint requests to Dr Holst:

    lueckstrasse, 91054 Erlangen, Germany; e-mail: alexandra.holst@

    k-erlangen.de

    2009 American Association of Oral and Maxillofacial Surgeons

    278-2391/09/6711-0310$36.00/0coi:10.1016/j.joms.2009.07.010

    82ilt, or extrude over years, making correct placementf implants impossible, or jeopardizing the long-termlinical success of a restoration. This is especially truef material properties are not considered and mini-

    um dimensions are ignored. In addition, the practi-ioner is challenged with increasing demands for es-hetic outcomes, which require that multiple biological,unctional, and biomechanical aspects be addressednd potential problems be identified preoperatively.he factors that have a direct influence on success or

    ailure include the amount of available alveolar ridge,oft tissue type, correct positioning of the implant inll 3 dimensions, design and material of the selectedestorative components, and adequate space for theefinitive restoration.1-3 Depending on the overallondition, an interdisciplinary team approach is indis-ensable for a predictable long-term success.Recent advancements in new materials and man-

    facturing techniques integrating computer-aidedesign/computer aided manufacturing (CAD/CAM)echnology into everyday laboratory routine allowndustrial fabrication of prosthetic components forlmost any clinical situation. Despite their many ad-antages such as biocompatibility, strength, and es-hetic properties, several requirements apply whenaterials such as oxide ceramics are used. In situa-

    ions where available space does not allow for mini-um required thickness of components, materialroperties can result in catastrophic failure under

    linical function. This is especially important when

    mailto:alexandra.holst@uk-erlangen.demailto:alexandra.holst@uk-erlangen.de

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    HOLST ET AL 83estoring posterior implants where functional occlu-al loads are the highest. In many cases, long-termdentulism results in elongation of the opposingeeth, limiting the availability of vertical height forroper restorations.4,5 Meticulous treatment planning

    s also a necessity in the anterior maxilla, where theunctional and esthetic outcome is significantly influ-nced by available hard and soft tissue morphology.The increasing acceptance of orthodontics in adult

    atients enables the creation of more favorable clini-al conditions before dental implants are being placed.he advantages are not only an improved estheticutcome but more stable tissue architecture. Pre-pros-hetic tooth alignment may also prevent the necessityor root canal treatment in cases in which elongatedeeth have to be prepared for full-coverage crowns,roviding sufficient space for all-ceramic restorations.mplant site development is typically limited to aefined region in most patients. Therefore, extensiveull-arch bonding is not warranted in most cases. The

    most easily applied orthodontic techniques for lo-alized orthodontic pretreatment are forced orth-dontic eruption and the application of orthodonticini-implants. An alternative approach is the use of

    efinitive osseointegrated dental implants as orth-dontic anchors. Although various types of orthodon-ic appliances may be attached to an abutment inhese situations, the technique requires adequatepace for primary implant positioning and can bepplied predominantly for uprighting tilted molars oresiodistal movements of teeth.The aim of this article is to present and discuss

    rthodontic options for implant site development ando discuss their limitations and potential risk factors indult patients.

    rthodontic Miniscrews for Localizedite Development

    The clinical use of orthodontic mini-implants oriniscrews is becoming increasingly popular. These

    ools are used as bone-retained anchorage devices toupport orthodontic tooth movement and to resisteciprocal reaction to applied orthodontic forces.6,7

    here are various screw systems available on thearket, with differing designs, dimensions, and inser-

    ion techniques.8 Orthodontic mini-implants havereatly increased the treatment options for dental andkeletal malocclusions because of the simplicity oflacement and removal, minimal invasiveness, andelatively low cost.9 In addition, the option of im-ediate loading and the elimination of shortcom-

    ngs frequently associated with extraoral anchorageevices (eg, patients noncompliance) result in in-reasing acceptance and clinical application in

    rthodontics.10 Currently, the greatest shortcoming Ef mini-implants is an unpredictable clinical failureate, ranging from less than 10% to greater than0%.11 Multiple scientific studies report that success

    s determined by a multitude of external factors, suchs bone quality and quantity and surrounding ana-omic structures,12-14 oral hygiene, insertion torque,15

    nsertion angle, root proximity,16 involvement of theeriodontal ligament,17 applied loads, and screw de-ign.18 This unpredictability is confirmed by severallinical studies. Chuang et al19 reported that place-ent of screws in nonkeratinized mucosa was associ-

    ted with clinical failure. In a study by Moon et al,20

    ignificant differences in success rate in adult patientsas related to placement site. The lowest success rateas seen between the second premolar and first mo-

    ar in young patients in both jaws. Although Park etl21 found better success rates in the maxilla, My-waki et al22 found no difference in the success rateor the maxilla and mandible. The underlying cause ofhe inconsistent results when comparing maxillarynd mandibular implants remains unclear. Reports inhe scientific literature agree that a predominant rea-on for failure of screws inserted into the alveolarone is excessive micromovement upon load applica-ion. Although theoretical ratios exist for dental im-lants,23 these values cannot be transferred to orth-dontic mini-implants because of the significantlyeduced size with resulting small surface area and theow horizontal forces being applied. The reason forhe lack of relevant data in orthodontic applications isaused by the difficulty in measuring displacementccurring in the low-micrometer range. This lack ofelevant data underlines the need for additional scien-ific research on this specific topic.

    The time of load application is discussed controver-ially in the literature. Recent reports conclude that aealing time seems unnecessary for mini-implants.oncluding from a review, Chen et al24 stated that

    ailures also happened before loading and several ex-erimental studies revealed that immediate loading ofhe threaded implant does not

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