Implant Esthetics:Form Meeting Function

55) of the cases studied were identified as requiring grafting procedures. This may be due to the pre-exist-ing anatomy and ridge resorption pattern in the maxillary anterior area (13, 14). However, deformities inthe anterior part of the maxilla may be related to the tooth biotype, genetic disorders, trauma, iatrogenicdamage of the bone, or other reasons independent of the maxillary resorption. The limited number ofcases present in our study that did not require graft procedures with the 3.25 mm diameter template maybe of importance for clinicians placing implants in the maxillary anterior area. Moreover, the use of con -ventional diameter implants would have resulted in a greater number of ridge defects and complicationsthan that reported in the present study population. In addition this may have increased the number ofpatients with more advanced classifications of deformities. Based on the number of ridge deformity com-plications documented in the present study, a knowledge and training in procedures for ridge augmenta -tion may be necessary for clinicians to obtain predictable results and manage surgical complications.

CONCLUSION

The present report proposed a new classification system for maxillary alveolar ridge deformities basedon CAT-scan implant simulation as a useful concept in order to more precisely predict treatment out-comes and the necessity for ridge augmentation prior to implant placement. The results indicate that

a high number of cases in the maxillary anterior area would require augmentation procedures in order toachieve ideal implant placement and restoration.

The ultimate goal of implant treatment is to surgically place implants in the most desirable posi-tion compatible with esthetics, phonetics, and function. Identification of the “optimal final toothposition” allows the restorative dentist and surgeon to analyze the impact of pathologic alterations

and to determine if soft or hard tissues need to be reconstructed to maximize function and esthetics (9).To achieve a long-lasting, ideal esthetic result with implants, in light of circumferential bone resorption thatusually occurs as part of the healing response around the implant head, the thickness of the bone on thebuccal side of an implant should be at least 2mm (8). The new method of classification presented in thecurrent study can identify this parameter.

Using the proposed new classification system, ridge classification of the bone defects may be identified andcomplications avoided due to more accurate treatment planning of implant size and position. The rela -tionship between the adjacent teeth and bone can also be observed by utilizing the radiographic template,which was worn by the patient when taking the CAT-scan.

The advantages of this new Implant Oriented Classification System (IOCS) include: 1) more accurate eval-uation of the clinical situation prior to surgery to determine treatment options. 2) the ability to evaluate theneed for hard tissue augmentation and simulate the necessary augmentation prior to surgery. 3) allowingselection of appropriate implant type and size before surgery. 4) using the radiographic template as a sur-

gical guide. 5) ability to communicate with restorative dentists and patients concerning treatment proce -dures and the expected outcomes.

A 3.25x10mm implant was selected as a guide implant for the new IOCS because, according to the liter -ature, this is the smallest permanent implant with a high success rate (10, 11). The ideal implant positionin this study was based on the radiographic template. The simulated implants were placed 3mm below theideal CEJ as a determined from the wax-up and radiographic template in order to provide enough apico-coronal room for esthetic prosthetic replacement (12).

The results reported in the present study revealed that 29.8% of the deformities were classified as Class I.Almost 66% of Class I deformities were classified as Class I-A. The remaining 34% of the Class I defectswould require some form of bone augmentation procedure for a successful long term prognosis. On theother hand 30% of the deformities were classified as Class IV according to the CAT-scan simulation. Thishigh number of Class IV deformities may be due to the fact that when these patients were evaluated at thetime of intra-oral examination the treating clinician, noting the ridge defect, subsequently sent the patientfor CAT-scan evaluation. Nevertheless, these findings indicate that a significant number of implant caseswould require ridge augmentation for implant placement or a modification in the treatment plan whichmay preclude the use of an implant in these sites.

According to our IDD CAT-scan data, 81% (116 of the total 144) of the implant sites and 92.7% (51 of

Depth: The implants were placed 3mm below the buccal cemento-enamel junction (CEJ) of the tooth posi-tion outlined by the radiographic template.

Proposal of a new classification system of ridge deformities:In the new proposed classification system ridges were categorized into seven different classes as follows:

Class I: The implant is completely surrounded by bone; no dehiscence or fenestration presentClass I-A : >= 2mm of facial plate of thicknessClass I-B : < 2mm of facial plate of thickness

Class II: Dehiscences are detected but no fenestrations are presentClass II-A: only buccal or palatal dehiscence is presentClass II-B: both buccal and palatal dehiscences are present

Class III: Fenestrations are detected but no dehiscence is presentClass III-A: only buccal or palatal fenestration is presentClass III-B: both buccal and palatal fenestrations are present

Class IV: Both dehiscences and fenestrations are present

RESULTS

The following represents the findings in our study utilizing 144 CAT-scan images to classify maxillaryanterior ridge deformities:

19.4% (28) of our locations were classified as Class I-A ridge deformities; 10.4% (15) were Class I-B;20.8% (30) were Class II-A alveolar defects; Class II-B were present on 12.5% (18) of our samples; 6.3%(9) of sites were fenestrations without dehiscences (Class III), and all were in the Class III-A category (buc-cal or palatal fenestration). Finally, 30.6% (44) of the potential implant site showed both dehiscences andfenestrations(Class IV). Class IV ridge deformities had the highest incidence followed by Class II- A, ClassI-A, II-B, I-B, and Class III.

Other findings showed that 28 Class I-A deformities were in 17 cases; 15 Class I-B deformities were in 14cases; 30 Class II-A deformities presented in 21 cases; 18 Class II-B deformities were found in 9 cases; 9Class III deformities were observed in 5 cases, and 44 Class IV deformities were noted in 18 cases. ClassII-A was the most common ridge deformities followed by Class IV, Class I-A, Class I-B, Class II-B and ClassIII.

There were 34 patients (61.8%) with more than one class of ridge deformities present and the remaining21 patients (38.2%) showed only one class of deformity.

DISCUSSION

Ridge Classification According to Ideal Implant Restorative PositionRidge Classification According to Ideal Implant Restorative Positionas Determined by CT Analysis with Radiographic Templatesas Determined by CT Analysis with Radiographic Templates

Park, Young Sang; Lee, Cheng-Hsun; Jalbout, Ziad; Cho, Sang-Choon; Froum, Stuart; Elian, Nicolas; Tarnow, Dennis. Ashman Department of Periodontology and Implant Dentistry, New York University

Author Year Classification

Siebert 1983Class I: buccolingual loss of tissue with normal apicocoronal ridge height

Class II: apicocoronal loss of tissue with normal buccolingual ridge width

Class III: combination-type defects (loss of both height and width)

Allen et al 1985

A: Apicocornal loss of tissue

B: Buccolingual loss of tissue

C: Combination

Mild: <3mm; Medium:3-6mm; Severe:>6mm

Lekholmand Zarb

1985

virtually intact alveolar ridge

minor resorption of alveolar ridge

advanced resorption of alveolar ridge to base of dental arch

initial resorption of base of dental arch

extreme resorption to base of dental arch

Misch andJudy 1987

abundant bone

barely sufficient bone

compromised bone

C-h: compromised height;

C-w: compromised width

deficient width

Defect Type Classification Detailed Description

Extractionwounds

Class I the envelope of bone is intact

Class II the envelope of bone is not intact

Fenestrations

Class I the implant surface penetrates the wall of bone by an insignificantamount and located within the envelope of bone

Class II there is a convexity and a significant portion of the implant is exposedoutside the envelope of bone for reasons of restorability

DehiscenceClass I the implant surface resides within the envelope of bone

Class II the implant surface resides outside the envelope of bone

Horizontal ridgedeficiencies

(HRD)

Class I the exposed implant surface resides within the envelope of bone

Class II the exposed implant surface resides outside the envelope of bone

Vertical ridgedeficiencies

(VRD)

Class I the vertical insufficiency is < 3 mm

Class II the vertical insufficiency is > 3 mm

Classification Suggested Treatment Options

Class IClass I-A Implant placement in ideal restorative position

Class I-B Implant placement without dehiscence or fenestration

Class IIClass II-A Staged GBR; Simultaneously GBR and implant placement; Ridge

expansion; Ridge splitting

Class II-B Staged GBR; Simultaneously GBR and implant placement;inlay/onlay block graft; distraction osteogenesis

Class III Staged GBR; Simultaneously GBR and implant placement;inlay/onlay block graft, Taper implants; Shorter implants

Class IV Distraction osteogenesis + Staged GBR or onlay graft; block graft

Fig 6. Class II-A Fig 7. Class II-B

Fig 8. Class III Fig 9. Class IV

REFERENCES1. Abrams H, Kopczyk RA, Kaplan A.

Incidence of anterior ridge deformities in par-tially edentulous patients. J Prosthet Dent1987;57:191-194.

2. Tinti C, Benfenati SP. Clinical Classificationof Bone Defects Concerning the Placement ofDental Implants. Int J Peri Resto Dent2003;23:147-155.

3. Seibert JS. Reconstruction of deformed, par-tially edentulous ridges, using full thicknessonlay grafts. Part I. Technique and woundhealing. Compend Contin Educ Dent1983;4:437-453.

4. Wang HL, Shammari KA.. HVC RidgeDeficiency Classification: A TherapeuticallyOriented Classfication. Int J Peri Resto Dent2002;22:335-343.

5. Lekholm U, Zarb GA. Patient selection andpreparation. Tissue Integrated Prosthesis1985;1:199-209.

6. Misch CE. Maxillary sinus augmentation forendosteal implants: Organized alternativetreatment plans. Int J Oral Implantol1987;4:49-58.

7. Spray J, Black V, Morris H, Ochi S. Theinfluence of bone thickness on facial margin-al bone response stage 1 placement throughstage 2 uncovering. Ann Periodontolgy2000;5:119-128.

8. Grunder U, Gracis S, Capelli M. Influence ofthe 3-D bone-to-implant relationship onesthetics+. Int J Peri Resto Dent2005;25:113-119.

9. Mecall RA, Rosenfeld AL. Influence ofResidual Ridge Resorption Patterns onFixture Placement and Tooth Position, Part3:Presurgical Assessment of RidgeAugmentation Requirements. Int J Peri RestoDent 1996;16:323-337.

10. Andersen E, Saxegaard E, Knutsen BM,Haanæs HR. A Prospective Clinical StudyEvaluating the Safety and Effectiveness of

Narrow-Diameter Threaded Implants in theAnterior Region of the Maxilla. Int J OralMaxillofac Implants 2001;16:217-224.

11. Lekholm U, Gunne J, Henry P, Higuchi K,Linden U, Bergstrom C, Van Steenberghe D.Survival of the Branemark implant in partial-ly edentulous jaws: A 10-year prospectivemulticenter study. Int J Oral MaxillofacImplants 1999;14:639-645.

12. Buser D, Martin W, Belser U. OptimizingEsthetics for Implant Restorations in theAnterior Maxilla: Anatomic and SurgicalConsiderations. Int J Oral Maxillofac Implants2004;19:43-61.

13. Atwood DA. Reduction of residual ridges:A major oral disease entity. J Prosthet Dent1971;26:266-279.

14. Atwood DA, Coy W. Clinical, cephalomet-ric, and densitometric study of reduction ofresidual ridges. J Prosthet Dent 1971;26:280-295.

Fig 1. Vertical and horizontal defects Fig 2. Edentulous ridge

“...the results indicate that a

high number of cases in the

maxillary anterior area would

require augmentation procedures

in order to achieve ideal implant

placement and restoration...”

Deformed partially edentulous ridges may compromise ideal implant placement and implant sur -vival. Deformities of the alveolar ridge may be caused by traumatic extraction, facial trauma, cleftsfrom birth defects, endodontic surgeries, removal of teeth with advanced periodontal disease, or

implant failures (1).

Several published reports classified ridge defects to help plan the treatment regimen for clinical correction(2). Seibert classified ridge deformities into three broad categories which are buccolingual tissue loss,apicocoronal tissue loss, and a combination of both (3). Recently, Wang and Al-Shammari described anew system, HVC classification, which is a modification of Seibert’s classification (4). These H (horizon-tal), V (vertical), and C (combination) defects were subdivided into S (small), M (medium), and L (large)subcategories. They also described treatment options based on this HVC classification. The advent andwidespread use of dental implants mandated careful evaluation of available bony ridge volume anddimensions. Lekholm and Zarb’s classification includes five stages of bone resorption, from minimal tosevere (5). Misch and Judy’s classification describes four divisions of available bone with treatmentoptions based on the amount of available bone height, width, and angulation (6). Tinti and Parma-Benfenati introduced a clinical classification of bone defects. They categorized “the envelope of bone”into five categories: extraction wounds, fenestrations, dehiscences, horizontal ridge deficiencies, and ver-tical ridge deficiencies (2). They also proposed treatment based on this classification.

To date, no published report has classified ridge deformities according to the position of the projectedimplant restoration. Currently, 3-dimensional radiographic images are available to evaluate hard tissueand to plan implant placement prior to surgery. Clinicians must focus on the 3-D bone-to-implant rela -tionship to establish the basis for an ideal and harmonic soft tissue situation that is stable over a long peri-od. Furthermore, many authors discussed the importance of at least 2mm of facial plate thickness (7, 8).When the facial plate is less than this critical thickness, the clinician may expect frequent and greater lossof vertical height of the facial plate.

The purpose of present study was to classify ridge deformities utilizing Computerized Axial Tomographic(CAT) scan images based on the ideal implant restorative position as determined by implant simulation.

MATERIALS AND METHODS

Clinical and CAT-scan data in this study were obtained from the Implant Dentistry Database (IDD)established at the Department of Periodontology and Implant Dentistry at New York UniversityCollege of Dentistry (NYUCD) Kriser Dental Center. This data set was extracted as de-identified

information from the routine treatment of patients. The IDD was certified by the Office of QualityAssurance at NYUCD. This study is in compliance with the Health Insurance Portability andAccountability Act (HIPAA) requirements and was approved by the IRBA.

CAT-scans were selected with the following criteria:-Only maxillary anterior missing teeth were included.-At least two consecutive missing teeth were required.-Images had to show at least one remaining anterior tooth, which was used as a guide for angula -

tion.-Radiographic templates used during taking of the CAT-scan were a prerequisite for this study.-Unclear CAT-scan images were excluded from this study

One thousand and five hundred CAT-scans were screened from the NYUCD Department ofPeriodontology and Implant Dentistry IDD. Fifty five cases satisfied the selection criteria. In these 55 sub-jects, 144 implant sites were evaluated.Characteristics of the measurements:

-All the measurements were performed and documented using CAT-scan software(SimPlant 8.0,Materialize, Glen Burnie, MD, USA) in a IDD by two independent investigators

-In all CAT-scan images, one 3.25x10mm parallel side simulated implant was positioned for everysingle edentulous area.

-Every simulated implant was placed in the ideal tooth position according to following protocol:Position: The implants were placed according to the tooth position outlined by the radiographic tem-

plate.Angulation: The implants were placed according to the angulation of the adjacent existing tooth.Inclination: The implants were placed using the adjacent existing tooth/teeth and the tooth position

outlined by the radiographic template as guides.

Table 1. Classifications of ridge defects Table 2. Tinti’s clinical classification

Table 3. New classification and treatment options Fig 3. Metal exposure due to insufficient facial bone

Fig 4. Class I-A Fig 5. Class I-B

This Presentation was Sponsored by New York University Department of Implant DentistryAlumni Association (NYUDIDAA) and the Office for International Program