Fixed Partial Dentures and Crowns Supported by Very Small ...

Fixed Partial Dentures and CrownsSupported by Very Small Diameter Dental

Implants in Compromised SitesDennis Flanagan, DDS

After trauma or years of boneresorption patients can presentfor implant treatment with

variable amounts of bone volume,length and height of ridge, and in-terocclusal space. Some sites cannotaccept the standard sizes of manyavailable implants without site devel-opment. Bone augmentation is an op-tion for increasing the available bonevolume if a standard diameter implantis required by the clinician. Standarddiameter implants are in the range of3.75 to 4.2 mm. However, in the non-esthetic zone an increase in bone vol-ume by augmentation procedures maynot be required. There is some debateas to the true supportive quality ofgrafted bone.1 Extra-cortical graftedbone has been known to resorb afterplacement.1 Bone formed in graftedareas can become trabecular but thereis no evidence that grafted boneprogresses to cortical bone. Implantsupport depends on cortical bone. Ifgrafted bone does not resist occlusalforces then the presenting natural baseof bone is the sole means of supportfor the restoration.1

Some residual ridges are very thinand will not accept a standard diame-ter (3.75–4.1 mm) implant within theconfines of the available bone with a 1to 2 mm of bone circumferential thick-ness. Small coronal dehiscences maybe grafted or ignored by placing theimplant slightly deeper to account forany anticipated osseous crest resorp-

tion. A smaller diameter implant maybe considered. There are small diam-eter implants available in a range from3.0 to 3.3 mm. Also available are verysmall or “mini” 1.8 to 2.5 mm diam-eter implants. These implants havebeen used primarily in multiples toretain complete removable overden-tures in the maxilla and mandible.2,3

The term mini has also been used todescribe very short length implantswith standard or larger diameters.4

There are case reports that demon-strate where compromised sites are re-stored with 1.8 to 3.3 mm diameterimplants that support fixed partial den-ture prostheses.5–7 These implantshave been used primarily as transi-tional or as temporary implants to sup-port temporary prostheses althoughlarger implants are undergoingosseointegration.

However, these very small diameterimplants, when used individually or inmultiples or in combination with largersized implants, may offer adequate sup-

port for crowns or fixed partial denturesin selected circumstances.

CASE GPThe patient, a 42-year-old man, pre-

sented for restoration of his missingteeth #24 and 25 (Figs. 1–3) (Table 1).5

Retained deciduous central incisorswere without succedaneous incisors.Radiographs and study casts were madefor analysis. His occlusion was a ClassII division 2 with a 100% overbite com-promising the interocclusal availablespace. Occlusal abrasion had occurred,further reducing the available interoc-clusal space. After the deciduous teethwere removed the ridge contour wasmapped using a bone sounding tech-nique. The site had adequate height butthe width was too narrow and length ofthe ridge was 11 mm. Clearly, standardwidth implants would not fit in the spaceavailable without orthodontic treatmentbut after a consultation the patient de-clined treatment. The ridge length

Private practice, Willimantic, CT.

ISSN 1056-6163/08/01702-182Implant DentistryVolume 17 • Number 2Copyright © 2008 by Lippincott Williams & Wilkins

DOI: 10.1097/ID.0b013e31817776cf

Very small diameter (1.8 –3.3mm) dental implants may be suc-cessfully used to support fixed par-tial dentures in edentulous sites ofcompromised bone width or length.Very small implants can be success-fully used in highly selected siteswhere there is adequate bone densityand bone volume for immediate im-plant stability. Adequate or aug-mentable attached gingiva may be arequirement. A small diameter im-plant presents less of an obstacle forangiogenesis and there is less percuta-neous exposure and bone displacement

as compared with standard sized im-plants. In posterior sites, roundedand narrow prosthetic teeth presentsmall occlusal tables to minimize ax-ial and off-axial directed forces.Multiple splinted implants may benecessary to minimize metal fatiguefrom cyclic loading. Anterior resto-rations supported by mini implantsmay need occlusal relief to minimizethe effects of cyclic loading.(Implant Dent 2008;17:182–191)Key Words: mini implant, occlusalscheme, bone density, bone ridge

182 FIXED PARTIAL DENTURES AND CROWNS IN COMPROMISED SITES

would not allow proper placement ofsmall diameter 3.25 mm implants. Thereideally needs to be 3 mm between eachimplant and 1.5 mm between each im-plant and its adjacent tooth, totaling 12.5mm including the diameter of the im-

plants, exceeding the 11 mm availablelength. Options for treatment were dis-cussed. The placement of small 1.8 mmimplants and subsequent construction ofa fixed prosthesis replacing teeth #24and 25 was then decided upon. The pa-tient accepted the treatment plan andthat no provisional restoration would beplaced during the healing integration orprosthetic construction phases.

The area was infiltrated in the an-terior mandible, facially and lingually,with 1.8 mL of articaine. A vacu-formed surgical guide was used. Asplit thickness apically positioned flapwas raised with a #15C scalpel to in-crease the resulting zone of attachedgingiva. Each osteotomy was startedwith a #4 round burr. Then a 1.2 mmdrill was used to complete the osteot-omy to a 15 mm depth. Type II bonewas encountered. Only external irriga-tion was used. The implants wereplaced with a specific technique asdescribed by the manufacturer. Theimplant was placed and turned with athumb wrench device. A ratchet de-vice is used to complete the place-ment. When turning becomes difficult,after one complete turn of the implant,a waiting time of 1 minute is observedto allow the bone to recover from thecompression of the advancing implant.The implants were placed without in-cident (Fig. 1). Inventory forced theuse of 2 different coronal designs. Thepatient was instructed in after-care andprescribed chlorhexidine oral rinse.He returned at 1 week for follow-upand had healed well with no compli-cations. An integration/healing phaseof 11 weeks was observed, whereuponhe returned for construction of a fixedprosthesis. The anterior mandible wasagain infiltrated with a small amountof articaine (0.4 mL) (Septocaine) forgingival anesthesia. The coronal por-tion of each implant was slightly pre-pared with a fine diamond burr toachieve parallelism and to acceptsplinted crowns (Fig. 2). Impressionswere made with a polyvinyl siloxanematerial. No provisional prosthesiswas made. A 2-unit porcelain fused tonoble alloy metal splint was con-structed that avoided direct centric andexcursive contacts. The dental labora-tory technician was instructed to applyan extra layer of die separator to insurea passive fit. Two weeks later the es-

thetics and function of the constructedprosthesis were evaluated. The prosthesiswas cemented with zinc phosphatecement. The patient has successfullyfunctioned with the prosthesis with nocomplications for 4 years (Fig. 3).

CASE SRA 61-year-old women had a cari-

ous tooth #30 extracted (Figs. 4–6)(Table 1). After 4 months of healing,two 2 � 1.5 mm implants (Intra Lock,Ultimatics, Ardmore, OK) wereplaced and restored with a 2 unit por-celain fused to metal crown splint.

CASE VMA 42-year-old women lost #30

due to failed endodontic therapy (Figs.7–10) (Table 1). The tooth was sec-tioned and atraumatically extractedand the site allowed to heal for 4months. Two one-piece 3 mm � 12mm (BioHorizons) were placed flap-lessly by infiltration local anesthesia(articaine). After 4 months waiting forosseointegration, the coronal ends wereprepared for splinted crowns. Thecrowns were cemented with zinc phos-phate cement. The patient has beenfunctioning successfully for 2 years.

CASE JCA 40-year-old man had lost his

mandibular right posterior teeth (Figs.11–13) (Table 1). The site at #28 wasadequate but the edentulous site at#29–32 was very narrow, precludingimplant placement without extra-cortical bone grafting. Four 2 � 1.5mm (IntraLock) and a 4 � 0 mm (3-I)implants were placed and restoredwith a splinted fixed partial denture.

DISCUSSION

Small diameter implants havebeen used for retention of completeremovable maxillary and mandibularoverdentures but there are also re-ports for their use in fixed prosthet-ics (Fig. 14).5

Table 1 lists 25 patients who weretreated with very small implants thatsupport fixed partial dentures and havebeen in service for at least 2 years. Thepatients received a multiple of verysmall diameter or combination of small,very small, and standard-sized diameter

Fig. 1. Two mini implants were placed toreplace absent succedaneous mandibularincisors.Fig. 2. The coronal portions of the implantswere slightly prepared for parallelism.Fig. 3. A 2 unit splinted fixed partial denturewas constructed and cemented with zincphosphate cement. There has now been 4years of uneventful function.

IMPLANT DENTISTRY / VOLUME 17, NUMBER 2 2008 183

implants. These cases demonstrate thatsingle and multiple very small implantsmay successfully support crowns orfixed partial dentures where there is ap-propriate bone and occlusal consider-ations. These sites are usually found inthe posterior mandible and anteriormaxilla and mandible.

Because bone volume and qualityand ridge length can present the implan-tologist with a challenge for restorativetreatment, creative but effective solu-tions may need to be considered. Anup-to-date knowledge of the array ofimplant sizes and shapes is an asset fortreatment.

There are implant diameters avail-able from 1.8 to 7 mm, intuitively; asmaller diameter implant may presentless of an impediment or obstacle forangiogenesis to the peri-implant bone.However, there also should be ade-quate bone density to resist occlusalforces placed on the implants via fixedprostheses. The smaller surface areaand volume of these implants places

more force per square millimeteragainst the encasing bone than largerdiameter implants, so there needs to beocclusal force control.

Bone density of type I, II or III,bone site length of at least 4 mm, boneavailable height of at least 10 mm andat least 1 mm of attached or augment-able gingiva are desirable. Any in-traoral location that exhibits thesequalities may be appropriate. How-ever, less dense bone may require theuse of longer small diameter implantsto resist occlusal forces and presentless per square millimeter of bonecompression during service. That is,during function, lateral occlusal forceswill exert a greater per square milli-meter force against the supportingbone with smaller diameter implantsthan larger diameter implants. If thebone cannot resist this lateral com-pressive force the implant may movein the bone and fibrous replacementmay be initiated resulting in implantfailure.

Conversely, there may be physio-logic advantages to very small diame-ter implants. An advantage that verysmall diameter implants have overstandard diameter implants is thelesser amount of linear or circumfer-ential percutaneous exposure and bonedisplacement. The circumference of a2 mm implant is (� � diameter) 6.28mm whereas the circumference of astandard 4.0 mm diameter implant is12.56 mm. The very small implant hashalf of the linear percutaneous expo-sure thus exposing less of the implant-gingival attachment to bacterial attack.

There is also a smaller silhouetteof the very small diameter implant thatmay present a barrier to angiogenesisand osteogenesis. Because dental im-plants are cylinders or near-cylinders,a mathematic calculation of the outlineform or the silhouette area, of a 2 � 10mm implant may be compared with a4 � 10 mm implant. Where the area isdiameter (width) � height. So, 2 � 10mm � 20 mm2 and 4 � 10 mm � 40

Table 1. Table of Patients Treated With Very Small Diameter Implants That Support Fixed Partial Dentures and Crowns

PatientNo.

ImplantsImplantSites Implant Sizes

Deemed BoneType Comments

PW 3 18, 19 2 � 10 II FlaplessPW-2 3 30, 31 2 � 10 II FlaplessGP 2 24–25 1.8 � 15 II Apically positioned flapTS 3 17, 18, 19 Two-2 � 10, 2 � 11.5 III FlaplessJC 5 28–32 3 � 13, 2 � 10 II #28 Immed. siteMS 3 24, 25, 26 Two-3.25 � 13, 1.8 � 18 II #24 � 2 Immed. sitesMD 2 19 2 � 13 II FlaplessSM 3 28, 29, 30 Two-2 � 10, 2 � 13 III FlaplessBN 3 18, 19, 20 4 � 10, 3.25 � 10, 2 � 10 III Apically positioned flapBN-2 2 25, 27 3.25 � 13, 2 � 15 II Apically positioned flapFS 2 19 2 � 10 II FlaplessRK 3 30, 31, 32 2 � 10 III Apically positioned flapCM 2 24, 25 2 � 15 III FlaplessBL 2 19, 20 2 � 10 II Apically positioned flapPS 3 28–31 3 � 12, two-2 � 10 II Apically positioned flapPS-2 2 18, 19 2 � 10 II FlaplessRG 2 19 2 � 10 III Free gingival graftRG-2 2 30 2 � 10 III FlaplessBM 2 19 3.25 � 10, 2 � 10 III FlaplessAS 4 19–25 Two-3.25 � 10, two-2 � 10 I Apically positioned flapBD 2 30 2 � 10 II Apically positioned flapmL 2 30, 31 4 � 7, 2 � 10 II Apically positioned flapLH 2 19,20 2 � 10, 4 � 10 II #20 Delayed placementCR 4 25–29 Three-1.8 � 15, 2 � 15 III FlaplessRH 3 23–25 1.8 � 18 II Immed. placementCS 2 24, 25 2 � 15 II Apically positioned flapAP 3 8, 9, 10 3.25 � 13, 2 � 13, 4 � 15 III Immed. functional loadBR 3 29, 30, 31 2 � 10 II Apically positioned flapVM 2 30 3 � 12 II Flapless

All prostheses have been in uneventful service for at least 2 years.


mm2. The 2 mm diameter implant pre-sents a barrier to the osseous physiol-ogy that is half that of the 4 mmdiameter implant.

With respect to volume of the cyl-inder, where volume � (� � 3.14) �(radius squared) � (cylinder height),then 3.14 � square mm � 10 mm �31.4 mm3 and, 3.14 � square mm �10 mm � 125.6 cm3.

So to compare these volumes:125.6/31.4 � 4.

The 4 mm diameter implant has 4times the osseous displacement ascompared with the 2 mm diameter

implant. This difference may be im-portant. Intuitively, this may be aphysiologic advantage for the verysmall diameter implant in that theremay be more of an available osseousblood supply for the implant support-ing bone or less of a barrier. In largerdiameter implants this larger barrier toblood supply or angiogenesis maycontribute to the classic “resorption tothe first thread” in the larger implant.The larger barrier may hinder angio-genesis and subsequent osteogenesisaround a newly placed implant. Bloodsupply at the osseous crest may behindered by the larger implant andproduce the characteristic resorptionto the first thread. This phenomenondoes not seem to be prevalent with the2 mm diameter implants. Figure 15shows 3 implants of different diameterthat were placed together in a row invarying widths of bone (Fig. 15). Thewidest 4.1 mm diameter implant on theleft demonstrates bone loss to the firstthread. The implant located in the mid-dle is a 2 mm diameter implant and

shows little or no radiographic boneloss. The right implant is a 3 mm diam-eter implant and shows slight bone loss.The 2 smaller diameter implants are 1piece, that is, they have no screw re-tained abutment. There has been somediscussion about the gap between theimplant fixture and the implant abut-ment, the so called “microgap” that maybe a bacterial reservoir that may causebone resorption to the first thread. Therelative importance of the implant diam-eter versus abutment microgap has yetto be elucidated.

This crest bone resorption phe-nomenon does not occur in submergedimplants but only after second stageuncovery and placement of an abut-ment. With the very small 2 mm di-ameter implants this does not seem tobe prevalent. This may be the result ofthe smaller diameter and/or the lack ofan abutment with a microgap.

The available bone for an implantsite in many cases can leave much tobe desired. In these cases, the occlu-sion, a reduced vertical dimension and

Fig. 4. Two implants were placed to support2 unit splinted crowns to replace #30.Fig. 5. The coronal portions of the implantswere slightly prepared for parallelism.Fig. 6. A 2 unit porcelain fused to noble alloysplint was constructed. The splint was con-structed with a flat rounded occlusal table tominimize off-axial forces and cemented withzinc phosphate cement.

Fig. 7. Two 3 mm diameter implants (BioHorizons) were placed to restore #30.Fig. 8. Radiograph of two 3 mm diameter implants placed to replace #30.Fig. 9. Coronal portions of the implants were slightly prepared for parallelism.Fig. 10. A 2 unit porcelain fused to noble alloy splint was constructed. The splint was con-structed with a flat rounded occlusal table to minimize off-axial forces and cemented with zincphosphate cement.


ridge length can present a dimensionalproblem for space. Very small diame-ter implants can fit into many of theseatrophic sites with adequate interim-plant and interocclusal spacing. Es-thetics may be a problem in certainsites and caution is advised here.

There needs to be adequate bonedensity and volume for implant stabil-ity and protective attached gingiva toaccept an implant supported restora-tion. These very small diameter im-plants can fit into sites that cannotaccept standard diameter implantswithout augmentation. The implants inthese case series were generally placedflaplessly or with a split thickness api-cally positioned flaps thus retainingthe periosteum and its blood supplyand retaining or increasing the at-tached gingiva. The bone in these atro-phic sites is typically type I or II andwell suited for initial implant stability.

Very small diameter implantshave been used for many years incompletely edentulous cases to retain

overdentures without bone grafting.Extracortical bone augmentation graft-ing may delay implant placement andthe resulting grafted bone may not betruly supportive for the implant formany months or years or possibly never.

The bone at the crest of a thinatrophic ridge may be dense corticalbone, which can be very supportivefor implants. Posterior sites in themandible, not in the esthetic zone,may be appropriate for very small di-ameter implants that support a fixedpartial denture. The forces in the pos-terior jaws can be greater than 1000 Nof force but this magnitude is in theaxial direction of the implant.8 Theoff-axial vector directive of theseforces is much less.

The cyclic loading that character-izes human occlusion may induce metalfatigue in very small diameter implants.Very small diameter implants may needto be used in multiples to preclude cy-clic loading metal fatigue and implantfracture in the posterior mandible9 (Figs.7, 11). Unpublished proprietary com-pany (Intralock) data and unpublisheddata from the author suggests that single2 mm diameter implants can withstandcyclic direct horizontal coronal loads of200 N of more than a million cycles.This force represents the maximumforce in the anterior jaws that may behumanly generated in the vertical oroccluso-apical direction but this forcewas applied directly horizontally orfacio-lingually for the test.

In anterior sites that have ade-quate width but inadequate length, avery small implant may be appropriatefor a single implant.5,10 The forces inthe anterior jaws can be about a thirdof the posterior forces, 50 to 200 N.These forces in occlusion, however,are delivered not axially but off axi-ally, a vulnerable direction for the im-plant. This may require more densebone to resist the higher per squaremillimeter force placed on the bone bythe smaller diameter implant body.Denser bone may preclude micro-movement of the implant and failureof the implant by fibrous replacement.The crowns in these cases may be bestleft slightly or somewhat out of occlu-sal contact in centric position and allexcursions.

Case selection is critical for theuse of very small diameter implants

Fig. 11. Two different brands (3-I and In-traLock) and diameters (4.1 and 2 mm, re-spectively) were used to appropriately fit intothe edentulous site. Adequate bone volumeat site #28 enabled placement of the stan-dard sized implant. The narrow edentulouswidth at sites #29–32 only accepted verysmall diameter implants.Fig. 12. These implants support a splinted 5unit fixed partial denture opposing naturaldentition.Fig. 13. A radiograph of the multiple smalldiameter implant with the splinted prosthesisin place.

Fig. 14. Multiple very small diameter implantshave been used for many years in clinicalpractice to retain mandibular overdentures.For successful treatment, adequate bonedensity, bone volume and attached gingivaare appropriate.

Fig. 15. Radiographic bone loss, typical to4.1 mm standard diameter implants, is evi-dent on the far left implant, and slight radio-graphic bone loss is seen on the 3 mmdiameter implant at the far right, but no ap-parent bone loss is evident on the 2 mm di-ameter implant in the middle.


supporting fixed partial dentures. Apatient may be a candidate for theseimplants if there are milder jaw forces,sites with denser bone with adequateattached gingiva.

The laboratory should be madeaware of the very small abutment andthe specifics of the occlusal scheme.Laboratory die material may be madeof polyurethane (PolyDie, Guilford,CT). This polymeric die material isinjected into the impression and thethin coronae of the implants can bereproduced for the working cast. Theresulting hard cast is then prepared forconventional crown and bridge tech-niques. A metal cervical collar and ahalf lingual coverage may be neededto support the porcelain of a porcelainfused-to-metal crown or fixed partialdenture.

In very dense bone during place-ment, the implant may need to beturned in 1 rotation increments with a1 minute rest between each. This is toallow the dense bone to recover orrecoil from the advancing self-tappingimplant to prevent bone overcompres-sion or implant fracture. An incisionmay or may not be necessary. Ade-quate attached gingiva is appropriatefor these implants.

Very small implants may be usedin conjunction with standard diameter(3.75–4.1 mm) implants to support afixed prosthesis where there is an areaof thin bone next to or near an areathat will accept a standard diameterimplant.

The cost of very small diameterimplants can about 20% to 50% lessthan standard diameter implants mak-ing treatment less expensive.

Placing very small diameter im-plants requires careful osseous, gingi-val, esthetic, and occlusal analysis butvery small diameter implants can beconsidered for use in a very selectivenumber of sites.

If during the osteotomy of a smalldiameter implant there is an unfore-seen bone density or site inadequacy,the use of a slightly larger diameterimplant that is able to attain betterinitial stability remains an option,given adequate space and density orbone manipulation techniques such asridge expansion or splitting. Conse-quently, it may be better to have a biasto placement of smaller diameter than

larger diameter implants. Larger diam-eter implants may be better suited inthe esthetic zone to provide for theemergence profile of the crown. How-ever, in anterior compromised sites,especially where there has been sitelength attenuation, smaller diameterimplants may be appropriate when theocclusal forces can be minimized oreliminated.

When placing very small im-plants, it is the experience of this au-thor that placement torque should notexceed 50 Ncm. Over compression ofthe bone may lead to osseous com-pression necrosis and the implant mayfail to integrate. Additionally, highertorque forces may cause fracture of theimplant shaft.

Although the forces of occlusionare less in the anterior jaws than in theposterior, chronically directed, offaxial, forces may cause implant orcomponent fatigue fracture or loss ofintegration of an implant. The prosthe-sis can be relieved in centric occlusionso as to avoid the chronic occlusalcontact (cyclic loading) and reduce theocclusal force impact.

Teeth may intrude as much as 250�m whereas an osseointegrated im-plant may intrude as much as 7 �m inbone. As the natural teeth functionallymove into bone, the opposing teethmay directly contact the prosthesis andthe discrepancy of movement mayproduce a loss of integration of thebone to implant contact and result infailure of the implant. There may beroom for error in that the opposingteeth also intrude giving the prostheticimplant less of a firm force against it.If the teeth adjacent to the supportingimplant intrude up to 250 �m and thencontact is made with the opposingteeth and they can intrude 250 �m aswell, then the sum of these intrusionsmay be as much as 500 �m before asolid contact is made. Should fixedprostheses be constructed shy of oc-clusion by 0.5 mm? Probably not, butthe exact amount of the relief, at thispoint in the technology, is an unan-swered question. Additionally, verysmall diameter implants may be proneto metal fatigue fracture if the prosthe-sis is placed in an inappropriate occlusalscheme. There is no evidence-basedimplant specific concept of occlusionbut metal fatigue may be an issue.11,12

Tarnow et al13 determined thatthere is a 1.4 mm circumferential bonecrest resorption about implants. Thismay mean that the appropriate implantsite width is the diameter of the pro-posed implant plus the 1.4 mm cir-cumferential bone resorption at eachperspective. Thus, a 4.0 mm diameterimplant would require: 4.0 mm � 1.4mm (facially) � 1.4 mm (lingually) �6.8 mm bone width. Very small 2 mmdiameter implants do not seem to dem-onstrate this phenomenon. Because ofthis information smaller diameter im-plants may be more appropriate formany compromised sites.14

Patients who present with a com-plete maxillary denture with remain-ing only mandibular anterior teethmay benefit from this modality. Thesepatients usually have thin atrophicposterior residual ridges that will notaccept a standard diameter implantwithout osseous grafting. Because theforces generated by these completedenture patients is generally less thanwith natural dentition, very small di-ameter implants may very successfullysupport fixed posterior splinted partialdentures. This treatment may preventthese patients from developing combi-nation syndrome, where there is super-eruption of the remaining anteriorteeth, fibrous replacement of the ante-rior maxilla and continued atrophy ofthe posterior edentulous ridges.

Knowledge of the available arrayof implant sizes is an asset for theimplantologist. Sites accepting thesesmall diameter implants in this caseseries were perceived to be of denserbone types I, II and III. There will bean increased per square millimeterforce exerted on the supporting boneby the implants during function. So,multiple implants may be necessary todissipate forces among the implants tominimize osseous stress.

Posterior prosthetic teeth weremade in these cases with roundedcusps and narrow occlusal tables thatpresent a small area for functional oc-clusal impact and to minimize off-axial forces. Zinc phosphate cement(Flecks) was used to lute all caseslisted but resin modified glass ionomeror resin cement can also be used.

Because these implants are notused with conventional osteotomy


drills but with very thin drills. If thethin ridge is split and expanded with a#15 scalpel the appropriate bone widthfor a proposed site may be the sum ofpostoperative peri-implant bone crestresorption of 1.4 mm at facial andlingual, or 2.8 mm. However, theremay not be as much resorption as astandard sized implant and the osseousresorption of 1.4 mm seems to notapply to mini implants. This type ofosseous crest resorption may not beprevalent with these implants possiblybecause of less impedance of theblood supply. So a very narrowerridge may successfully accommodatethe mini implant.

Very small diameter implants maybe used for single crowns where oc-clusal accommodations are made sothat there are no occlusal contacts. Ad-ditionally, very small diameter im-plants may be used to support fixedpartial dentures in multiples or in tan-dem with larger diameter implants.Occlusal schemes can be designedwith contact only in centric and noexcursive contacts.

Because the surgical placement ofmini implants is much less traumaticas compared with standard sized im-plants they may be useful for medi-cally compromised or elderly patients.

Complications and Caveats

There are caveats and complica-tions that need to be considered whenplacing very small diameter implants.Overcompression of the bone can re-sult in a failure to osseointegrate.However, it has been this author’s ex-perience that, with the use of a torquecontrolled handpiece, with less than50 Ncm insertion torque, this problemhas not been seen. Manual ratchetplacement use, where the placementtorque is unknown, may result in os-seous overcompression and loss of theimplant. Additionally, the use of ex-cessive placement torque may fracturethe narrow implant.

The osteotomy drill is very thinand may fracture during the osteot-omy. Careful drill manipulation is aconcern. If this occurs, multiple radio-graphic views, including computer-ized tomography, may be taken to ex-actly ascertain the drill fragment’sposition. Retrieval by osseous explo-ration is not a recommended course ofaction. Once the drill position is radio-graphically ascertained, the piece maythen be retrieved.

Metal fatigue of the implant coro-nas may be a long-term result of an“under-engineered” or a high cuspedfixed partial denture. That is, installa-tion of too few implants may not resistchronic occlusal forces, cyclic load-ing, and cause fracture of the narrowimplant coronal shaft. Additionally,placing high esthetic cusps may allowincreased lateral or off-axial forces tobe applied and thus fatigue the implantshaft.

CONCLUSIONS

In highly selected edentuloussites very small diameter, or mini,implants may be used to supportfixed prostheses.

Disclosure

The author claims to have no fi-nancial interest, directly or indirectly,in any entity that is commercially re-lated to the products mentioned in thisarticle.

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Reprint requests and correspondence to:Dennis Flanagan, DDS1671 West Main St.Willimantic, CT 06226Phone: 860-456-3153Fax: 860-456-8759E-mail: [email protected]


Abstract Translations

GERMAN / DEUTSCHAUTOR: Dennis Flanagan, DDS. Korrespondenz an: DennisFlanagan DDS.1671 West Main St., Willimantic, Conn.06226. Telefon: 860-456-3153, Fax: 860-456-8759, eMail:[email protected] Zahnimplantate mit sehr geringem Durchmessergestutzte feste Teilprothesen und -uberkronungen fur bee-intrachtigte Implantierungsbereiche

ZUSAMMENFASSUNG: Zahnimplantate von sehr gerin-gem Durchmesser (1.8–3.3 mm) konnen erfolgreich dazueingesetzt werden, feste Teilprothesen in den zahnlosen Be-reichen von beeintrachtigtem Knochengewebe mit zugeringer Breite oder Lange zu unterstutzen. Sehr kleine Im-plantate konnen in speziell ausgewahlten Bereichen erfolg-reichen Einsatz finden, vorausgesetzt, Knochendichte undKnochenvolumen reichen fur eine sofortige Stabilisierungdes Implantats aus. Entsprechend ausreichendes bzw. auf-baubares Zahnfleisch kann hierbei eine Voraussetzungdarstellen. Ein Implantat mit kleinem Durchmesser stellt eingeringeres Hindernis fur eine Gefaßbildung dar. Außerdemsind gegenuber normal großen Implantaten der Kontakt zurunverletzten Haut sowie die Gefahr einer Knochenluxationgeringer. Bei Implantierungsstellen im hinteren Mundraumbietet eine abgerundete und schmale Zahnprothetik kleineokklusale Brettchen, um daruber die in Achsenrichtung wirk-enden sowie entgegen der Achse laufenden Krafte zu min-imieren. Vielfach gespante Implantate konnen erforderlichsein, um eine durch die zyklische Belastung hervorgerufeneMetallermudung moglichst gering zu halten. Wiederherstel-lungslosungen mit Unterstutzung durch Mini-Implantate imvorderen Kieferbereich benotigen eventuell eine okklusaleEntlastung, um die Auswirkungen einer zyklischen Belastungzu minimieren.

SCHLUSSELWORTER: Mini-Implantat, okklusales Schema,Knochendichte, Knochenkamm.

SPANISH / ESPAÑOLAUTOR: Dennis Flanagan DDS.Correspondencia a: DennisFlanagan DDS, 1671 West Main St., Willimantic, Conn.06226. Telefono: 860-456-3153, Fax: 860-456-8759, Correoelectronico: [email protected] parciales fijas y coronas apoyadas por im-plantes dentales de diametro muy pequeno en lugaresproblematicos

ABSTRACTO: Los implantes dentales de muy pequeno ta-mano (1.8–3.3mm) pueden usarse con exito para apoyardentaduras parciales fijas en lugares desdentados donde elancho o largo del hueso se ha visto afectado negativamente.Los implantes muy pequenos pueden usarse con exito en

lugares altamente selectos donde existe una densidad delhueso y volumen oseo adecuados para ofrecer una estabilidadinmediata del implante. Tambien podrıa requerirse una encıaadecuada o aumentable conectada. Un implante de diametropequeno presenta menos obstaculos para la angiogenesis yexiste menos exposicion percutanea y desplazamiento delhueso comparado con implantes de tamano normal. En lu-gares posteriores, dientes postizos redondeados y angostospresentan pequenas tablas oclusales para reducir las fuerzasdirigidas axiales o no axiales. Multiples implantes con tab-lillas podrıan ser necesarios para reducir la fatiga del metal dela carga cıclica. Las restauraciones anteriores apoyadas porminiimplantes podrıan necesitar un alivio oclusal para reducirlos efectos de la carga cıclica.

PALABRAS CLAVES: Miniimplante, esquema oclusal, den-sidad del hueso, cresta del hueso.

PORTUGUESE / PORTUGUÊSAUTOR: Dennis Flanagan, Cirurgiao-Dentista. Correspon-dencia para: Dennis Flanagan DDS, 1671 West Main St.,Willimantic, Conn. 0622. Telefone: 860-456-3153, Fax: 860-456-8759, e-mail: [email protected] Parciais Fixas e Coroas Suportadas por Im-plantes Dentarios de Diametro Muito Pequeno em LocaisComprometidos

RESUMO: Implantes dentarios de diametro muito pequeno(1.8–3.3mm) podem ser usados com sucesso para suportardentaduras parciais fixas em locais desdentados de largura oucomprimento de osso comprometido. Implantes muito peque-nos podem ser usados com sucesso em locais altamenteselecionados onde haja adequada densidade de osso e volumede osso para imediata estabilidade do implante. Gengivaanexada adequada ou aumentavel pode ser um requisito. Umimplante de diametro pequeno apresenta menos de um obsta-culo para a angiogenese e ha menos exposicao percutanea edeslocamento do osso em comparacao com implantes detamanho padrao. Em locais posteriores, dentes proteticosarredondados e estreitos apresentam pequenas tabelas oclu-sais para minimizar forcas dirigidas axiais e extra-axiais.Implantes esplintados multiplos talvez sejam necessarios paraa fadiga do metal da carga cıclica. Restauracoes anterioressuportadas por mini-implantes talvez precisem de relevooclusal para minimizar os efeitos da carga cıclica.

PALAVRAS-CHAVE: Mini-implante, esquema oclusal, den-sidade do osso, rebordo do osso.

RUSSIAN /��: Dennis Flanagan, �� . �� : Dennis Flanagan DDS, 1671 West


Main St., Willimantic, Conn. 06226. ��: 860-456-3153, ��: 860-456-8759, �� :[email protected]��

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TURKISH / TURKCEYAZAR: Diçs Hekimi Dennis Flanagan. Yazısma icin: Den-nis Flanagan DDS, 1671 West Main St., Willimantic, Conn.06226 ABD. Telefon: 860-456-3153, Faks: 860-456-8759.eposta: [email protected] Dusmus Yerlerde Cok Kucuk Caplı Dental Im-planlar Tarafından Desteklenen Sabit Kısmi Protez Diçslerve Kronlar

OZET: Cok kucuk caplı (1.8–3.3 mm) dental implantlar,kemik genisliginin veya uzunlugunun tehlikeye dusmusoldugu dissiz yerlerde sabit kısmi protez disleri desteklemekuzere basarıyla kullanılabilir. Hemen yuklenen implantın sta-bilitesi icin yeterli kemik yogunlugu ve kemik hacmi olantitizlikle secilmis yerlerde cok kucuk implantlar basarıylauygulanabilir. Yeterli veya ogmantasyon yapılabilecek dis etibunun icin bir kosul olabilir. Kucuk caplı bir implant, anjio-genez icin daha az bir engel olusturur ve standart boyutluimplantlara gore perkutan acıklık ve kemik deplasmanı dahaaz duzeydedir. Posterior alanlardaki yuvarlanmıs ve dar pro-tez disler, aksiyal ve off-aksiyal yoneltilmis gucleri en azaindirmek icin kucuk okluzyon duzeyleri teskil eder. Cevrim-sel yuklemenin yol actıgı metal yorgunlugunu en aza in-dirmek icin splintlenmis multipl implantlar gerekebilir. Miniimplantlar ile desteklenen anterior restorasyonlarda cevrimselyuklemenin etkilerini en aza indirmek icin okluzyon rahatla-ması saglamak gereksinimi olabilir.

ANAHTAR KELIMELER: Mini implant, okluzyon planı,kemik yogunlugu, kemik kreti

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