Generic Root Form Component Terminology · available, offering countless combinations of implant body design, platform shapes, diameter, length, prosthetic con-nections, surface conditions,

32

A n endosteal implant is an alloplastic material surgi-cally inserted into a residual bony ridge primarily asa prosthodontic foundation.1 The prefix endo means

“within,” and osteal means “bone.”2 The major subcategory ofendosteal implants covered in this text are root form implants.The term endosseous also is used in the literature. Because theterm osseous also indicates bone, either term is acceptable.However, endosteal, periosteal, and transosteal are preferred.

Root form implants are the design most often used inrestoration of the partial or completely edentulous patient.The desire has always been to replace missing teeth withsomething similar to a tooth. Root form implant historydates back thousands of years and includes civilizationssuch as the ancient Chinese, who 4000 years ago carvedbamboo sticks the shape of pegs and drove them into thebone for fixed tooth replacement. The Egyptians, 2000 yearsago, used precious metals in a similar method, and a skullwas found in Europe with a ferrous metal tooth insertedinto a skull in similar fashion. Incas from Central Americatook pieces of sea shells and tapped them into the bone toreplace missing teeth3 (Fig. 3-1). In other words, to replacea tooth with an implant has always made sense. In reality,if the lay public was given a choice to replace a missingtooth with an implant or to grind down several adjacentteeth and connect them to a bridge to replace a missingtooth, making it harder to clean, and attempting to makethe adjacent teeth look similar to the condition before theirpreparation, the implant would be the obvious choice.

Maggiolo4 introduced the more recent history of implantdentistry in 1809 using gold in the shape of a tooth root. In1887 Harris5 reported the use of teeth made of porcelain intowhich lead-coated platinum posts were fitted. Many materialswere tested, and in the early 1900s Lambotte6 fabricatedimplants of aluminum, silver, brass, red copper, magnesium,gold, and soft steel plated with gold and nickel. He identi-fied the corrosion of several of these metals in body tissuesrelated to electrolytic action. The first root form design thatdiffered significantly from the shape of a tooth root was theGreenfield latticed-cage design in 1909, made of iridoplat-inum.7 The surgery was designed to use a calibratedtrephine bur to maintain an inner core of bone within theimplant. The implant crown was connected to the implantbody with an internal attachment after several weeks.Reports indicate this implant had a modicum of success.

Generic Root FormComponent Terminology

CHAPTER

3Carl E. Misch

Figure 3-1 Implant dentistry is the second oldest disciplinein dentistry (oral surgery [exodontia] is the oldest). Implants dateback more than 4000 years, when the Chinese carved bamboostakes and hammered them into the bone for fixed tooth replace-ment. This mandible, dated AD 600, was found in Honduras. IncaIndians carved sea shells into stakes and tapped them into thebone, such as this jaw with three incisors implanted. Calculus for-mation on these three implants indicate this was not a burial cere-mony, but a fixed, functional, and esthetic tooth replacement.

Surgical cobalt chromium molybdenum alloy was intro-duced to oral implantology in 1938 by Strock8 when hereplaced a maxillary left incisor single tooth, an implantthat lasted more than 15 years. In 1946 Strock designed atwo-stage screw implant that was inserted without a per-mucosal post. The abutment post and individual crownwere added after complete healing.9 The desired implantinterface at this time was described as ankylosis, which maybe equated to the clinical term rigid fixation. The first sub-merged implant placed by Strock was still functioning40 years later10 (Fig. 3-2).

Bone fusing to titanium was first reported in 1940 byBothe et al.11 Brånemark12 began extensive experimentalstudies in 1952 on the microscopic circulation of bone mar-row healing. These studies led to dental implant applicationin early 1960; 10-year implant integration was established in

Generic Root Form Component Terminology 33

dogs without significant adverse reactions to hard or soft tis-sues. Studies in human beings began in 1965, were followedfor 10 years, and were reported in 1977. Osseointegration, asfirst defined by Brånemark, denotes at least some direct con-tact of living bone with the surface of an implant at the lightmicroscopic level of magnification.13 The percentage ofdirect bone-implant contact varies. The term osseointegrationhas become a common term in the implant discipline,which describes not only a microscopic condition but also aclinical condition. A more generic term, osteointegration alsois used widely by the profession. To determine true osteoin-tegration by the original definition, the implant must beremoved and evaluated under a microscope. In reality, rigidfixation defines the clinical aspect of this microscopic bonecontact with an implant and is the absence of mobility with1 to 500 g force applied in a vertical or horizontal direction.Rigid fixation is the clinical result of a direct bone interfacebut also has been reported with a fibrous tissue interface.

No other person in recent history has influenced rootform implant concepts more than Brånemark. The docu-mentation of past clinical case studies, research of surgeryand bone physiology, healing of soft and hard tissues, andrestorative applications from Brånemark’s laboratory wereunprecedented. Adell et al.13 published their 15-year clinicalcase series report in 1981 on the use of implants in com-pletely edentulous jaws. About 90% of the reported anteriormandibular implants that were in the mouths of patientsafter the first year were still in function 5 to 12 years later.However, lower survival rates were observed in the anteriormaxilla. No implants were inserted into the posteriorregions of the mouth in the original clinical trials.

The use of dental implants to treat complete and partialedentulism has become an integral treatment modality inrestorative dentistry.14-17 A 1990 survey indicated more than90% of oral and maxillofacial surgeons, periodontists, andprosthodontists and more than 50% of general dentists hadattended a professional development course on implantsduring the preceding 3 years.18 The 1988 National Institutesof Health consensus panel on dental implants recognizedthat restorative procedures using implants differ from thoseof traditional dentistry and stressed the necessity foradvanced education.19

Many practitioners are taught the use of a specific man-ufacturer’s implant system rather than the theory and com-prehensive practice of implant dentistry. The increasingnumber of manufacturers entering the field use trade namesfor their implant components (often unique to a particularsystem), and such names have proliferated to the point ofcreating confusion. Several different terms or abbreviationsnow exist that describe similar basic components.20-23

To make conditions worse, in the team approach toimplant treatment the widening referral base often requiresthat the restoring practitioner be knowledgeable regardingmany implant systems. With the required knowledge of mul-tiple systems and the lack of uniformity in component names,communication is hampered among manufacturers, dentists,staff, laboratory technicians, students, and researchers. Inaddition, the incorporation of implant dentistry into thecurriculum of most predoctoral and postdoctoral programsfurther emphasizes the need for standardization of termsand components in implant dentistry.24 This chapter pro-poses a generic terminology, first introduced by Misch forendosteal implants, that attempts to blend the continuity andfamiliarity of many implant systems with established defini-tions from the Illustrated Dictionary of Dentistry and the glos-saries of the Academy of Prosthodontics and the AmericanAcademy of Implant Dentistry.1,2,25,26

GENERIC IMPLANT BODYTERMINOLOGY

Root form implants are a category of endosteal implants thatare designed to use a vertical column of bone, similar to theroot of a natural tooth. Although many names have beenapplied, the 1988 National Institutes of Health consensusstatement on dental implants and the American Academy ofImplant Dentistry recognize the term root form1,19 (Fig. 3-3).The exponential growth of implant use over the last 20years has been paralleled by an explosion of the implantmanufacturing field. Currently, more than 90 designs areavailable, offering countless combinations of implant bodydesign, platform shapes, diameter, length, prosthetic con-nections, surface conditions, and interfaces.26-47

The most common root form design combines a separateimplant body and prosthodontic abutment to permit theimplant placement under the soft tissue during initial bonehealing. A second surgical procedure is required to uncoverthe implant as a two-stage surgical approach, separated bythe hard tissue healing process. The design philosophy is toachieve clinical rigid fixation that corresponds to a micro-scopic direct bone-to-implant interface without interveningfibrous tissue occurring over any significant portion of theimplant body.

More recently, implant body designs with a permucosalsection have been developed to allow a one-stage (unsub-merged) approach. Also, the immediate load techniques arereported more widely on two-piece and one-piece implantdesigns.

The macroscopic body design can be a cylinder, thread,plateau, perforated, solid, hollow, or vented; the surface canbe smooth, machined, coated, or textured. The designs areavailable in submergible and nonsubmergible forms in avariety of biocompatible materials. Three primary types of rootform endosteal implants are available based on design.26

Figure 3-2 Al Strock, from Boston, Mass., invented a seriesof two-stage endosteal implants in 1948. This patient received oneof these implants to replace a maxillary lateral incisor. The patientpresented in 1986 with the implant still in function 38 years later.

D E N TA L I M P L A N T P R O S T H E T I C S34

Cylinder (press fit) root form implants depend on a coatingor surface condition to provide microscopic retention andbonding to the bone and usually are pushed or tapped intoa prepared bone site. They can be straight, tapered, or con-ical. Screw root forms are threaded into a bone site and havemacroscopic retentive elements for initial bone fixation.These root forms may be machined, textured, or coated.Three basic screw-thread geometries are V-thread, buttressthread, and power (square) thread designs that are com-bined with different geometric shapes. Threaded implantsare now available in straight, tapered, conical tapered,ovoid, and expanding designs. Combination root forms havemacroscopic features of the cylinder and screw root forms.

Micro or macro thread features, alternating thread pitch,depth, and self-tapping features can be combined to createa myriad of implant designs from which to choose. Thescrew or combination root form designs also may benefitfrom microscopic retention to bone through varied surfacetreatment (machined, textured, etched, resorbable blastmedium [RBM]) and the addition of coatings or macroscopicfeatures such as baskets, vents, grooves, ledges, plateaux,and fins.48-61 Root forms also have been described by theirmeans of insertion, healing, surgical requirements, surfacecharacteristics, and interface.20-23

IMPLANT BODY REGIONS

The implant body may be divided into a crest module(cervical geometry), a body, and an apex (Fig. 3-4).

Crest module

Body

Apex

Figure 3-4 An implant body is the portion of the dentalimplant that is designed to be placed into the bone to anchorprosthetic components. The implant body has a crest module,body, and apex.

Figure 3-3 Hundreds of different implant body designs are available in the world today.These generally relate to three different categories: cylinder implants (top row), screw designimplants (middle row), or a combination (bottom row), which usually are pressed into position andhave a macro body design similar to a thread form. (Courtesy Charles English, Little Rock, AR.)

Generic Root Form Component Terminology

Implant Body

A solid screw implant body design with a blunt apex offerssignificant advantages to the practitioner with limitedexperience or limited availability of different implantsystems. A solid screw is defined as an implant of a circularcross section without any vents or holes penetrating theimplant body. A number of manufacturers provide thisdesign. The V-shaped threaded screw has a long history ofclinical use12,13; the most common thread outer diameter is3.75 mm, with a 0.4 mm depth of thread and a crest mod-ule about 2 mm in height and crestal diameter of 4.1 mm.The various lengths range from 7 to 20 mm; lengths from10 to 16 mm are the most widely used. This design now isoffered in a variety of diameters (narrow, standard, wide) tobetter answer the mechanical, esthetic, and anatomicalrequirements in different areas of the mouth.62,63

A solid screw permits the preparation and placement ofthe implant in dense cortical bone and in fine trabecularbone. The surgery may be modified easily to accommodateboth extremes of bone density. The solid screw permits theimplant to be removed at the time of surgery if placementis not ideal. A solid implant may perforate the inferiorborder of the mandible, nares, or maxillary sinus withoutinherent complication if the apex is smooth or blunted.The solid screw may be plasma spray-coated with titaniumor hydroxyapatite to marginally increase the functionalsurface area, microlock the bone, and take advantage ofbiochemical properties related to the surface coating(e.g., bone bonding or bone growth factors).

Manufacturers also may provide slightly smaller or largerimplant diameters for use in limited anatomical situationsor surgical complications. A solid screw also permits theimplant to be removed at the Stage II surgery if angulationor crestal bony contours are not adequate for long-termprosthesis success.

The functional surface area of a threaded implant isgreater than a cylinder implant by a minimum of 30% andmay exceed 500%, depending on the thread geometry. Thisincrease in functional implant surface area decreases thestress imposed on the implant bone interface and alsodepends on thread geometry.

A cylinder implant design system offers the advantage ofease of placement, even in difficult access locations. Forexample, in the very soft D4 bone of the posterior regionsof the maxilla, a 70 : 1 handpiece, rather than a handwrench, is needed to insert a threaded implant design. Verysoft bone otherwise may be displaced during the handratchet procedure, and the implant will not be rigid.A cylinder implant may be pressed into the bone by handin hard or soft bone. The cylinder system also has somebenefits for the single-tooth implant application, especiallyif the crown height of the adjacent teeth is large. Extendersare needed for the screw implant placement in these situa-tions, as well as additional armamentarium to insert thecover screw of the implant. Cylinder systems also are easierand faster to place because bone tapping is not required.The speed of implant rotation during insertion and theamount of apical force in implant insertion are also lessrelevant.

However, most cylinder implants are essentially smooth-sided and bullet-shaped implants that require a bioactive orincreased surface area coating for retention in the bone.If these same materials were placed on a threaded design,

35

the surface area of bone contact would be more than30% higher compared with the smooth cylinder design.The greater the functional surface area of the bone implantcontact, the better the support system for the prosthesis. Inaddition, if bone loss occurs around a coated implant, abiological smear layer attaches to the coating. The contami-nated coating often must be removed for the bone toreadapt to the implant. However, once the coating isremoved, the cylindrical implant primarily imposes shearloading to the bone implant interface. Bone is 65% weakerin shear force compared with compression. As a result,future bone loss is even more likely. Once the surface isdecontaminated and bone is regenerated next to the implant,the threaded implant still can transmit compression andtensile forces to bone. Hence surgical correction of boneloss has better prognosis with screw-type implants.

Crest Module

The crest module of an implant is that portion designed toretain the prosthetic component in a two-piece system; italso represents the transition zone from the implant bodydesign to the transosteal region of the implant at the crestof the ridge. The crest module also may be designed to exitthe soft tissue in some implant systems (e.g., the ITIimplant system). The abutment connection area often has aplatform on which the abutment is set; the platform offersphysical resistance to axial occlusal loads. An antirotationfeature often is included on the platform (external hexa-gon) but may extend within the implant body (internalhexagon, Morse taper, internal grooves). The implant bodyhas a macroscopic design (e.g., threads or large spheres),whereas the crest module is often smoother to impairplaque retention if crestal bone loss occurs. The apicaldimension of the crest module varies greatly from onesystem to another (0.5 mm to 5 mm).

The platform features a coupling that is above or belowthe crestal bone level. Nonrotational features are typicallypart of this element. The classic connection above the plat-form is an external hexagon of dimensions varying withmanufacturers and implant diameter.

A high-precision fit of the external hexagon, flat-to-flatdimension is paramount to the stability of the implantbody–abutment connection.62-66 Internal connections canbe of the internal hexagon or octagon type. Other geomet-rics include octagonal, cone screw, cylinder hexagon,spline, cam tube, and pin slots. The connection is receivedby slip-fit or friction-fit with butt or bevel joint. All aim atproviding a precise mating of the two components withminimal tolerance. A multitude of patents have been filedtouting the merits of a particular design, and one canexpect the field will see more creative versions as the fieldfurther expands.

Implant Collar

A cervical collar may be incorporated: its design varies fromstraight to flared neck, beveled, reverse bevel, tapered,smooth, surfaced, or microthreaded. Designs that incorpo-rate a microscopic component into the implant bodies bycoatings with hydroxyapatite or titanium often have animplant collar at the superior aspect of the crest module.Prevention of hydroxyapatite exposure above the bone maybe one solution to decrease the potential bacterial liability.

From observations of a number of hydroxyapatite-coatedcylinder Integral implants exhibiting morbidity, Block andKent67 made recommendations to reduce complications,including (1) caution in placing implants in thin bone orextraction sites without adequate bony coverage or graftingand (2) primary closure to prevent premature exposure andpossible bone loss. However, the amount of bone remodel-ing following implant placement is difficult to predict. Theinclusion of a metal collar allows functional remodeling tooccur to a more consistent region on the implant.68 Studieson osseous healing around implants69,70 suggest that crestalremodeling is limited to the smooth region of the collar.As a result of this remodeling, the sulcular epitheliummigrates to the base of the implant collar. However, no sig-nificant differences in the probing depths between healthyimplants with and without coronal collars have beennoted69 probably because of the close adaptation of circularfibers encircling the implant neck.71

Besides the possible prevention of hydroxyapatite expo-sure, an additional advantage of using a machined coronalportion is the potential for an improved interface at theabutment connection. Although the machined collarregion may provide this advantage, the collar contributeslittle to the biomechanical support at the bony crest wherestresses are most severe; one must consider this factor intreatment planning and prosthesis design. Therefore themachined collar limited in height to 0.5 to 1 mm providesthe biological and abutment connection advantages andlimits the biomechanical disadvantage.

GENERIC PROSTHETIC COMPONENTTERMINOLOGY

Misch and Misch26 developed a generic language forendosteal implants in 1992. This language is presented in anorder following the chronology of insertion to restoration(Fig. 3-5). In formulating the terminology, five commonlyused implant systems in the United States were referenced.

Ten years later, the dramatic evolution of the U.S.implant market has resulted in the complete disappearanceof some and the multiplication and mutation of othersthrough mergers and name changes. To make mattersworse, even if the company remained the same, changes inthe implant line and component design (dimensions orconnection types) may have taken place. A 1998 articlereported that in the U.S. alone the profession now has tochoose from more than 1300 implants and 1500 abutmentsin various materials, shapes, sizes, diameters, lengths,surfaces, and connections.62 More than ever, a commonlanguage is needed. Just as in pharmacology in which themultiplicity of pharmaceutical components makes itimpossible to list them all by proprietary names but by cat-egory, implant components still can be classified into broadapplications/indications categories, and the practitionershould be able to recognize a certain component categoryand know its indications and limitations.

At the time of insertion of the implant body or Stage Isurgery, a first-stage cover is placed into the top of theimplant to prevent bone, soft tissue, or debris from invad-ing the abutment connection area during healing. If thefirst-stage cover is screwed into place, the term cover screwmay be used.

D E N TA L I M P L A N T P R O S T H E T I C S36

A B

A B C

A B

Prosthesis screw

Coping

Analog

Transfer coping(abutment or implant body)

Hygiene screw

Abutment

Second-stage permucosal extension or healing abutment

First-stage cover screw

Implant body

Implant bodyAbutment

A.B.

A.B.

IndirectDirect

A.B.C.

For screw retentionFor cement retentionFor attachment

Figure 3-5 Implant components most often have terms thatare different for each company. Misch and Misch26 published ageneric language that applies to any product. This language per-mits improved communication between referring doctors andlaboratories, which often must be familiar with several differentsystems. (From Misch CE: Contemporary implant dentistry, ed 2,St Louis, 1999, Mosby.)

After a prescribed healing period sufficient to allow asupporting interface to develop, a second-stage proceduremay be performed to expose the implant or to attach atransepithelial portion.25 This transepithelial portion istermed a permucosal extension because it extends the implantabove the soft tissue and results in the development ofa permucosal seal around the implant. This implant compo-nent also is called a healing abutment because Stage II uncov-ery surgery often uses this device for initial soft tissuehealing (Figs. 3-6 and 3-7).

In the case of a one-stage procedure, the surgeon mayhave placed the permucosal extension at the time ofimplant insertion or may have selected an implant bodydesign with a cervical collar of sufficient height to besupragingival. In the case of immediate load, the permu-cosal healing abutment may not be used at all if a tempo-rary prosthesis is delivered on the day of surgery or maybe used until the suture removal appointment and the

Generic Root Form Component Terminology 37

Figure 3-7 An intraoral view of eight second-stage permu-cosal extensions that were inserted into the implant bodies.

Figure 3-6 The permucosal extension (PME) attaches to theimplant body and allows the soft tissue to heal and mature aroundthe future implant abutment. The PME may be the same size as thecrest module of the implant body (left) or slightly larger (right) andhelps develop the emergence contour of the implant crown.

Abutment for screw

Figure 3-8 An abutment for screw retention is used for ascrew-retained bar or fixed prosthesis. (Courtesy BioHorizons,Birmingham, Ala.)

temporary teeth delivery. The healing abutment is availablein multiple heights to accommodate soft tissue variationsand also can be straight or flared or anatomical to assist inthe soft tissue healing sculpture.

The abutment is the portion of the implant that supportsor retains a prosthesis or implant superstructure.25 A super-structure is defined as a metal framework that fits theimplant abutment(s) and provides retention for a removableprosthesis1 (e.g., a cast bar retaining an overdenture withattachments) or provides the framework for a fixed prosthesis.Three main categories of implant abutment are described,according to the method by which the prosthesis or super-structure is retained to the abutment: (1) an abutment forscrew retention uses a screw to retain the prosthesis or super-structure; (2) an abutment for cement retention uses dentalcement to retain the prosthesis or superstructure; and (3) anabutment for attachment uses an attachment device to retain aremovable prosthesis (such as O-ring attachment) (Figs. 3-8to 3-10). Many manufacturers classify the prosthesis as fixed

One-pieceabutment

Abutment forcement

Angledabutment

Profileabutment

Figure 3-9 Abutment for cement retention may be onepiece (far left) or two pieces, which are retained by a separateabutment screw.

O-ring abutment

Figure 3-10 Abutment for attachment is used for removableprostheses that are implant retained. These may be used for com-plete dentures and/or partial dentures.

Figure 3-11 On a custom abutment, porcelain may be builtbetween the crown margin and the abutment-to-implant position.This buildup allows the crown margin to be above the bone, yetthe subgingival region has pink or tooth-colored porcelain and acustomized shape to improve esthetics.

whenever cement retains the prostheses, fixed/removablewhen screws retain a fixed prosthesis, and removable whenthe restoration can be removed by the patient. This descrip-tion implies that only screw-retained prostheses may beremoved. The description is not accurate because the den-tist also may remove a fixed-cemented prosthesis. Hence thegeneric language in this chapter separates prostheses intofixed or removable as does traditional prosthetics. The abut-ment may be screwed or cemented into the implant body,but this aspect is not delineated within the generic termi-nology. Each of the three abutment types may be classifiedfurther as straight or angled abutments, describing the axialrelationship between the implant body and the abutment.An abutment for screw retention uses a hygiene cover screwplaced over the abutment to prevent debris and calculusfrom invading the internally threaded portion of the abut-ment during prosthesis fabrication between prostheticappointments.

The paucity of abutment design of a decade ago has beenreplaced by a plethora of options. The expansion of implantdentistry, its applications for esthetic dentistry, and thecreativity of manufacturers in this competitive market areresponsible for the explosion of implant abutment stylesavailable today. In the abutment for cement category, thedoctor may choose from one- and two-piece abutments,University of California—Los Angeles (UCLA) type (plasticcastable, machined/plastic cast to cylinder, gold sleevecastable), two-piece esthetic, two-piece anatomical, two-piece shoulder, preangled (several angulations), or tele-scopic mullable ceramic (Figs. 3-9, 3-11, and 3-12). Theabutment for screw category also has been enlarged withone- and two-piece overdenture abutments of differentcontours and heights.

An impression is necessary to transfer the position anddesign of the implant or abutment to a master cast forprosthesis fabrication. A transfer coping is used in traditionalprosthetics to position a die in an impression25 (Fig. 3-13).Most implant manufacturers use the terms transfer and copingto describe the component used for the final impression.

D E N TA L I M P L A N T P R O S T H E T I C S38

Figure 3-12 A customized abutment with tooth-coloredceramic and ideal emergence profile from the implant body. If thetissue shrinks in the future, the crown will appear longer, but thetitanium color of the abutment will not be evident.

Therefore a transfer coping is used to position an analog inan impression and is defined by the portion of the implantit transfers to the master cast, either the implant body trans-fer coping or the abutment transfer coping.

Two basic implant restorative techniques are used tomake a master impression, and each uses a different designtransfer coping, based on the transfer technique performed.An indirect transfer coping uses an impression materialrequiring elastic properties.25 The indirect transfer coping isscrewed into the abutment or implant body and remains inplace when the set impression is removed from the mouth.The indirect transfer coping is parallel-sided or slightlytapered to allow ease in removal of the impression andoften has flat sides or smooth undercuts to facilitate reori-entation in the impression after removal. A direct transfercoping usually consists of a hollow transfer component,often square, and a long central screw to secure it to the abut-ment or implant body and may be used as a pickup impres-sion coping. After the impression material is set, the directtransfer coping screw is unthreaded to allow removal of theimpression from the mouth. Direct transfer copings takeadvantage of impression materials having rigid propertiesand eliminate the error of permanent deformation becausethey remain within the impression until the master modelis poured and separated (Fig. 3-14).

An analog is something that is analogous or similar tosomething else.25 An implant analog is used in the fabricationof the master cast to replicate the retentive portion of theimplant body or abutment (implant body analog, implantabutment analog). After the master impression is obtained, thecorresponding analog (e.g., implant body or abutment forscrew) is attached to the transfer coping and the assembly ispoured in stone to fabricate the master cast (Figs. 3-15, 3-16,and 3-17).

A prosthetic coping is a thin covering,25 usually designedto fit the implant abutment for screw retention and serve asthe connection between the abutment and the prosthesis or superstructure. A prefabricated coping usually is a metal

Generic Root Form Component Terminology 39

Type of restoration

Single-tooth restoration Multiple-unit restoration

Color-code scheme

Closed-tray technique Open-tray technique Closed-tray technique Open-tray technique

Direct-transfercoping screw

Direct-transfer—nonhexed

Direct-transfer—hexed

One-piece abutmentfor cement—nonhexed

Ball-topscrew

Ball-topscrew

Straight abutmentfor cement—hexed

Straight abutmentfor cement—hexed

Direct-transfercoping screw

Indirectimpressioncoping—nonhexed

Indirect analog

O-Ringabutment

O-Ring abutmentanalog

Blue5.0 mm

Green4.0 mm

Yellow3.5 mm

Figure 3-13 An indirect transfer (far left and center ) is inserted into an implant body orabutment for screw retention and a closed tray impression is made. The impression is removedand the transfers are connected to an analog and reinserted into the impression. A direct impres-sion transfer (far right ) uses an open tray to make the impression. The direct transfer copingscrew must be unthreaded before the impression is removed from the mouth. (CourtesyBioHorizons, Birmingham, Ala.)

Figure 3-14 These eight maxillary implants are connectedto two-piece indirect impression transfers, which engage the hexa-gon of the implant platform. A closed-tray impression is made, andthe indirect transfer copings are unthreaded from the implant bod-ies, connected to implant body analogs, and reinserted into theimpression before pouring of the cast.

Implant analog O-ring abutment analog

Figure 3-15 Analogs may represent an abutment forscrew retention, an implant body (left ), and/or an abutment forattachment (right ).

regardless of the implant system used; the term is descrip-tive of the function of the component rather than its pro-prietary name.

References

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10. Shulman L: Personal communication, 1990.11. Bothe RT, Beaton LE, Davenport HA: Reaction of bone to

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12. Brånemark PI: Osseointegrated implants in the treatmentof the edentulous jaw: experience from a 10-year period,Scand J Plast Reconstr Surg Suppl 16:1-132, 1977.

13. Adell R, Lekholm U, Rockler B, et al: A 15-year study ofosseointegrated implants in the treatment of the edentu-lous jaw, Int J Oral Surg 6:387, 1981.

14. Adell R, Ericsson B, Lekholm U, et al: A long-term follow-upstudy of osseointegrated implants in the treatment of totallyedentulous jaws, Int J Oral Maxillofac Implants 5:347-359,1990.

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16. Kirsch A, Ackerman KL: The IMZ osteointegrated implantsystem, Dent Clin North Am 33:733-791, 1989.

17. Misch CE: The Core-Vent implant system. In Endosteal dentalimplants, St Louis, 1991, Mosby.

18. Schnitman PA: Education in implant dentistry, J Am DentAssoc 121:330-332, 1990.

19. National Institutes of Health consensus developmentconference statement on dental implants, J Dent Educ52:824-827, 1988.

20. English CE: Part I. Cylindrical implants, Calif Dent Assoc J16:17-26, 1988.

21. English CE: Part II. Questions need answering, Calif DentAssoc J 16:26-34, 1988.

22. English CE: Part III. An overview of the systems, Calif DentAssoc J 16:34-38, 1988.

23. Christensen GE, Christensen RP: Clin Res Assoc Newsletter13:1-4, 1989.

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Figure 3-16 An indirect closed-tray impression in a“customized” impression tray, which also is related to the incisaledge of the patient to the laboratory technician. The indirectimpression transfers have been attached to implant body analogsand reinserted into the closed-tray impression.

Figure 3-17 The impression in Figure 3-16 is mountedagainst the opposing arch (with a bite registration not pictured).In this particular system the indirect transfer coping may be a one-or two-piece component. A one-piece component does notengage the hexagon and does not transfer the position of theantirotational hexagon from the mouth to the model. The two-piece indirect transfer does allow the transfer. The laboratory canremove the indirect transfer copings, insert the abutments forcement retention, and prepare them before making a transitionprosthesis. Some dentists also will make a metal casting for thefinal restoration on this model.

component machined precisely to fit the abutment. Acastable coping usually is a plastic pattern cast in the samemetal as the superstructure or prosthesis. A screw-retainedprosthesis or superstructure is secured to the implant body orabutment with a prosthetic screw (see Table 2-1).

A generic terminology has been developed to facilitate the communication between implant team members,

Generic Root Form Component Terminology

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