PARIPEX - INDIAN JOURNAL OF RESEARCH Volume-7 | Issue-1 | January-2018 | PRINT ISSN No 2250-1991

ORIGINAL RESEARCH PAPER Dental Science

FINISH LINES IN FIXED PROSTHODONTICS KEY WORDS: sliding joint

effect, remargination, bevel.

Dr Mohammad
Govt Dental College Srinagar *Corresponding Author
Altaf Tantray*
Dr Sandeep Kour Govt Dental College Srinagar
Dr Shazia Govt Dental College Srinagar
Dr Shazana Nazir Govt Dental College Srinagar
ABSTRACT

Background: Finish line design is very important in any tooth preparation as it affects not only sealing discrepancy but also
seating discrepancy. Finish line location is decided by aesthetics, periodontal health, biological width and occlusocervical(OC)/
faciolingual (FL)dimension ratio of tooth preparation.Finish line exposure is needed during impression procedures.

Definition: It may be well defined as ii. Based on location of finish line

I. Line of demarcation a. Supragigival
II. Peripheral extension of tooth preparation b. Equigingival
III. The planned junction of different materials c. subgingival

Features of finish lines: must be distinct, uniform, and smooth and iii. Based on margin angle by Kuwata et al
should follow alveolar bone crest and free gingival margin. a. Margin angle b/w 0 and 300
a.Bevelled margins
Requirements of finish lines: it should be b. Margin angle b/w 31and600
a.chamfer
Easy to prepare, easy to duplicate in impression, conservative and c. Margin angle b/w 61 and 900
provide sufficient strength to restoring material. a.Shoulder
iv. Pardo's classification:
Functions of finish lines: Ÿ Inclined vertical Feather edge, shoulder with bevel
I. Finish line design provides an estimation of tooth reduction as Ÿ Horizontal margins Shoulder, chamfer
feather edge is most conservative and shoulder is the least
conservative. FEATHER EDGE
ii. Finish line design helps in measuring surface detail recording I. ADVANTAGE: Most conservative
ability of an impression material. II. DISADVANTAGE: Over contoured restorations
iii. Distinct finish line helps in ditching
iv. Distinct finish line aids in remargination for proper marginal • Not recommended now
adaptation of wax pattern. KNIFE EDGE
I. It is most conservative type of f.l.
Criteria for successful finish line design: these are as under ii. It gives >1350 cavosurface angle.
I. Acceptable marginal adaptation: According to David F Pascoe, iii. Pointed end tapered fissure bur is used
sealing discrepancy equals seating discrepancy times sine of
marginal metal angle. Shoulder finish line produces marginal INDICATIONS
metal angle of 900. That is why, sealing discrepancy equals
I. Large pulp chambered tooth
seating discrepancy. Beveling reduces marginal metal angle,
ii. Finish line on cementum
thus minimizes seating discrepancy.
iii. MOD onlay
ii. Tissue tolerant surface
iii. Adequate contour: conservative finish lines like feather edge
and knife edge produce overcontoured restoration leading to ADVANTAGES
periodontal problems gingival recession, unaesthetic black I. Easy to prepare
triangular spaces, alveolar bone loss. ii. Most conservative
iv. Adequate strength: finish line design should provide adequate iii. Burnishable type of finish line
strength to restoring material. iv. Ideal for marginal adaptation

Criteria for finish line design selection: DISADVANTAGES

The selected finish line design should I. Indistinct margin
I. provide predictable level of marginal integrity. ii. Over contoured restoration
ii. present smooth materials to the sulcus, to minimize plaque iii. Marginal distortion
accumulation. iv. Difficult to wax and cast
iii. provide acceptable esthetics.
Bevel: It may be well defined as “SLANTING EDGE”. GPT8Thedition.
Classification of finish line design configuration:
I. Based on configuration of finish line It is classified as low angled short bevel and high angled long bevel
a. Feather edge in accordance with A.J. Hunter.
b. Knife edge
c. bevel Functions of bevel: it improves marginal seal, produces strongest
d. shoulder enamel margin, improves retention and resistance form of the
e. chamfer preparation, creates sliding joint effect and produces burnishable
margins.
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PARIPEX - INDIAN JOURNAL OF RESEARCH Volume-7 | Issue-1 | January-2018 | PRINT ISSN No 2250-1991
INDICATION of BEVEL: Eisman et al Alveolar bone crest Finish line 2mm
Facial margin of maxillary partial coverage restoration ABC coronal to ABC
Inlay margin Fugazoto et al ABC Finish line 3mm
Onlay margin coronal to ABC
Glickman et al Free gingival margin 0.5mm apical to
SHOULDER FINISH LINE: finish line design for tooth preparation FGM FGM
in which the gingival floor meets the external axial surfaces at
approximately a right angle. Flat-end tapered diamond end cutting Biologic width violation causes gingivitis, periodontal pocket
diamonds are used to prepare shoulder finish line. formation, recession and tooth-restoration interface display.

INDICATION: All ceramic crowns and labial margin of porcelain Remedy for biological width is
fused to metal crowns. I. Surgical recontouring of alveolar bone
ii. Orthodontic extrusion with supracrestal fibrotomy weekly
ADVANTAGES
I. Aesthetically acceptable Depending on margin placement, types of finish lines
ii. Good crown contour a) SUPRAGINGIVAL FINISH LINE
iii. Adequate bulk b) EQUIGINGIVAL FINISH LINE
iv. Less distortion c) SUBGINGIVAL FINISH LINE

DISADVANTAGES Supragingival finish line is used in low lip line cases.

I. Arduous to prepare
II. Least conservative Advantages are as under:
III. Danger of pulp exposure I. Easy preparation
IV. Inferior marginal integrity ii. Easy to finish
V. Lacks sliding joint fit iii. Easy to duplicate
iv. Easy to varify fit of restoration
Types of the shoulder are sloped shoulder, radial shoulder and v. Easy mentainance
shoulder with bevel.
Equigingival finish line: In a study on dogs Marcum et al found
Sloped shoulder: finish line design for tooth preparation in which margins at crest caused less inflamation than those above or below
the gingival floor meets the external axial surfaces at it. F. Micheal Gardener, Margins of complete crowns – Literature
approximately 1200. It is indicated in facial margin of metal ceramic review JPD Oct 1982, 48(4), 396-400.
crown.
Subgingival finish line: it is best avoided unless indicated.
Radial shoulder: Shoulder finish line with rounded gingivoaxial
line angle and900 cavosurface angle. Radial shoulder on all ceramic Indications:
preparation combines the support of ceramic with stress reducing I. Aesthetics
radial shoulder. II. Subgingival caries
III. Erosion
Shoulder with bevel: it is used in facial margin of metal-ceramic IV. Abfraction
crowns, proximal box of inlays and onlays and occlusal shoulder of V. Dentinal hypersensitivity
onlays and mandibular three –fourth crowns.
Rationale of subgingival finish lines:
Factors deciding placement of finish lines: Ÿ Tooth-restoration interface latency
Ÿ To maximize resistance and retention form of tooth
Aesthetics: The subgingival finish line suits for the high lip line and preparation
equigingival and supragingival suits for low lip line patients. Ÿ To make significant contour alteration

Biological width: it is the combined dimension of epithelial Guidelines for subgingival margin placement are as under
attachment (0.97mm) and connective tissue attachment a. Free gingival margin(FGM)
(1.07mm) coronal to alveolar bone crest. It is measured by bone b. Alveolar bone crest(ABC)
sounding. Minimizing transgingival probing depth by sulcus depth
measures the biological width. I. When sulcus depth is 1.5mm,finish line 0.5mm apical to FGM.
ii. When sulcus depth (d) is >1.5mm,finish line is ½ sulcus depth,
Table1. Biological width as per authors apical to FGM.
author Biologic width iii. When sulcus depth is >2mm,crown lengthening is done.
Nevin and sukrow 2.73mm
Garguilo et al 2.04mm Subgingival finish line exposure is carried out by mechanical,
chemical, rotory gingival curettage and surgical methods.
Table2. Biological width variation as per intraoral position:
tooth Biologic width References:
1. Contemporary fixed partial denture by Rudolph Rosenstiel
anteriors 1.75mm 2. Fundamentals of fixed partial denture by H.T. Shillinburg
premolars 1.97mm 3. Theory and practice of fixed prosthodontics by Tylman
4. The science and art of laminates by Galip and Gurel
molar 2.08mm 5. Carranza’s clinical periodontology 10th edition
6. Protocols for predictable aesthetic dental restoration by Irfan
Table3. finish line position as per various authors in relation 7. Science of dental materials by Philips.
to various landmarks 8. Text book of Prosthodontics 1st edition by Rangaragan
9. Terry E. Donovan, Cervical margin design with contemporary esthetic restorations,
Author Landmark Margin –landmark Dent Clin N Am 48 (2004) 417–431
separation 10. Terry E. Donovan, Current concepts in gingival displacement, Dent Clin N Am 48
(2004) 433–444
Nevin and sukrow Base of sulcus Finish line coronal to 11. Charles J. Goodacre, Designing tooth preparations for optimal success,Dent Clin N
base of sulcus Am 48 (2004) 359–385
12. F Micheal Gardener, Margins of complete crowns – Literature review JPD Oct
Garguilo et al Base of sulcus Finish line at base of 1982, 48(4), 396-400
sulcus 13. A J Hunter, Gingival crown margin configurations: a revew and discussion. Part I :
Terminology and Widths JPD 1990, 64: 548-552
Wilson and Mynard Base of sulcus 0.5mm coronal to 14. George Salem, margin design for esthetic posterior metal ceramic crowns. JPD Oct
sulcus
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1988 60(4) 418-424
15. Martin Henry Berman, complete coverage crowns and the gingival sulcus JPD Mar
1973 29(3) 301-309
16. David F Pascoe, Analysis of geometry of finish lines JPD Aug 1978 40(1), 157-162
17. R Pilo, Incomplete seating of cemented crowns: A literature review April 1988 59(4)
429-433
18. M. Harry Parker, Resistance form in tooth preparation, Dent Clin N Am 48 (2004)
387–396
19. Nadim Z. Baba, Gingival Displacement for Impression Making in Fixed
Prosthodontics, Dent Clin N Am 58 (2014) 45–68
20. Burney M. Croll, D.D.S. Emergence profiles in natural tooth contour. Part
I:Photographic observations. JULY 1989 VOLI’ME 62 NUMBER I
21. Hurney &I. Croll, D.D.S. Emergence profiles in natural tooth contour. Part II: Clinical
Considerations. J.PROSTHET DENT 1990; 374-9.)

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