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INTRODUCTION No doubts, orthognathic surgical procedures have widened the envelope of treatment that can be rendered to the patient. Be it orthodontics or orthognathic surgical procedures, the diagnosis of the patient should not be underestimated. www.indiandentalacademy.com
Treatment planning in orthodontics & dento facial orthopedics is carried out taking into consideration the amount of growth left behind in the patient. But orthognathic surgical procedures are usually carried out in adults where major growth of skeletal tissues is completed.Through the various cephalometric analysis, we try to evaluate structures that are either over grown or under grown www.indiandentalacademy.com
Most of the values that are used by an orthodontist are angular values. But the surgeon at the table will not be benefited by angular values to alter skeletal tissues. On the other hand linear values will guide the surgeon to do the right job in an easy way. www.indiandentalacademy.com
Soft tissue cephalometric analysis for orthognathic surgery patients JOS – 1980 – october The soft tissue covering the teeth and bone are highly variable in thickness www.indiandentalacademy.com
Landmarks 1.Glabella 2.Columella point 3.Subnasale 4.Labrale sup. 5.Stomion sup. 6.Stomion inf. 7.Labrale inf. 8.ML sulcus 9.ST pogonion
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11.ST menton .Cervical point .HR Plane
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The facial form (G-Sn-Pg`)– describes ? →Positive and negative angles →Specificity → Locating the problem → Microgenia, micrognathia or retrognathia www.indiandentalacademy.com
The lower face to throat angle (Sn-Gn`-C ) Critical – antero posterior dysplasias An obtuse lower face to neck angle - ?
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Proportionality of the lower face height to depth – greater than 1. Vertical dimension – anterior facial proportionality. Ratio of G – Sn to Sn – Me`
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POSITION OF THE LIP
1.The naso labial angle (Cm-Sn-Ls) Antero posterior dysplasias Acute / obtuse Inclination of columella of nose
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Antero posterior lip position Ls to (Sn-Pg`) – 3 ± 1 Li to (Sn-Pg`) – 2 ± 1
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The labio mental sulcus Depth perpendicular to Li-Pg` Average – 4mm. Factors ?
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The lower third of face Length of U lip : lower lip = 1:2
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The key factor in determining the vertical position of maxilla ? Average - ? VME Vs short U Lip
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Inter labial gap
Lightly touching to approx 3 mm VME / short upper lip
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Cephalometrics for orthognathic surgery
Charles J.Burstone et al – JOS – 1978 University of Connecticut Adv – 1.The chosen landmarks and measurements can be altered 2. Comprehensive appraisal includes all of facial bones 3. Rectilinear measurements study casts for mock surgery www.indiandentalacademy.com
Landmarks Sella Nasion Articulare
PTM
Subspinale Pogonion Supramentale ANS Menton Gnathion
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PNS Mand plane Gonion
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The cranial base
HP - base line for comparison First – length of cranial base – not absolute value – correlated with values Distance bet post max & mand
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Horizontal Skeletal Profile
The angle of skeletal facial convexity Sign convention - +ve / -ve N-A , N-B , N-Pg ? – parallel to HP
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Vertical Skeletal
Ant – N-ANS , ANS-Gn Post – N-PNS , MP-HP
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Vertical Dental
Ant – U 1 – NF & L 1 – MP Post – U 6 – NF & L 6 – MP
Incisor Angulation U 1 – NF & L 1 – MP
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Length of Max & Mand
PNS – ANS – parallel to HP This + N-ANS & N-PNS – Max Ar – Go – length of Mand Go – Pg – Mand body B – Pg – prominence of the chin
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Facial keys to orthodontic diagnosis and treatment planning Arnett & Bergman – 1993 – April Purpose – 1. To present an organised, comprehensive clinical facial analysis 2. To discuss the soft tissue changes associated with orthodontic & surgical correction www.indiandentalacademy.com
Three questions to be asked ? On what should the treatment plan depend upon ? Wylie analyzed 10 patients using 5 cephalometric analysis & concluded “cephalometrics should not be the primary diagnostic tool for dentofacial diagnosisâ€? Burstone - correcting the dental discrepancy does not necessarily improve facial imbalance , it might even‌ www.indiandentalacademy.com
1. Outline form and symmetry Fac ht to width; 1.35:1(M)&1.3:1(F) The question to be asked ? Example ?
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2. Facial level
Inter pupilary line – horizontal RP Structures compared ? If inter pupilary line is not parallel – a constructed HR line
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3.Midline alignments Soft tissue landmarks – NB,NT,F,C Dental landmarks – UIM, LIM
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Causes of dental shifts Spaces, tooth rotations, missing teeth, buccaly/lingually positioned teeth,restorations that change tooth mass, congenital tooth mass difference from left to right Dental shifts – treated ? Skeletal shifts – treated ? www.indiandentalacademy.com
4. Facial one thirds
Thirds of the face - ? (55-65mm) ↑/↓ lower third height - ? Determining factor in facial height
changes
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Lower one third evaluation
Upper / lower lip lengths ? – Normals? Ratio = 1:2 ( proportionate lips‌ )
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Upper tooth to lip relation.
Normal – 1-5mm ( women ↑ ) Disharmony → 1. ↑/↓ anatomic U lip length 2. ↑/↓ maxillary skeletal length 3. Thick upper lips 4. The angle of view Over impaction – premature aging “Gingival smile” is never treated to ideal at the expense of under exposing the incisors in relaxed lip position www.indiandentalacademy.com
Inter labial gap
Normal – 1- 5mm ( women ↑) Conditions with ↑ I L gap ?
Closed lip position
↑ Mentalis activity,alar narrowing, lip strain – vertical skeletal ↑ Lip redundancy – VMD / mand retrusion with deep bite
Smile position lip level
Ideal – ¾ CH to 2mm of gingiva www.indiandentalacademy.com
The profile angle
G – Sn – Pg’ ( 165 – 175° ) General harmony – not specific Most important key – AP surg correction
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The Naso labial angle
Upper lip ant & columella at subnasale 85 – 105° (women ↑) → lip tension, lip thickness
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Maxillary sulcus contour Gently curved – lip tension Tense lips Vs Flaccid lips ( Thick )
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Mandibular sulcus contour Gently curved – lip tension Deeply curved – flaccid ( 2° to max incisor impingement in Cl - 2 deep bite ) Flattened – tension ( Cl – 3 )
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The orbital rim
Indicator of AP max position Deficient OR – retruded max ( osseous structures are deficient as groups ) Globe – 2-4 mm ahead ( normal, flat, protruded ).
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Cheek bone contour ? Correlates with AP max position Main indicator of max retrusion Apex at cheek bone point (CP) – 2025mm inf & 5-10mm lat to outer canthus
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Nasal base – lip contour
Continuation of C B contour line Indicator – max & mand skeletal AP Normal – MP directly behind alar base
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Nasal projection
Sn – nasal tip ; 16 – 20mm Indicator of AP max position ↓ NP contra max advancement
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Throat length & contour Neck throat junction – Me’ Mand set back – Changes length – Sag In short sagging throat, mand SBContra. Genioplasty & Suction lipectomy – useful adjunct
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Sub nasale – pog’ line Burstone – U Lip ; 3.5±1.4mm L Lip ; 2.2±1.6mm The Burstone lip relationship is true only if they are of same thickness
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Grummon’s analysis Grummon & Kappayne – 1987 – JCO Useful tool to provide clinically relevant information about specific locations & amounts of asymmetry. Very helpful in the planning of orthognathic surgeries Comparative & quantitative PA ceph analysis – not related to normative data www.indiandentalacademy.com
Structures in PA cephalogram
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1. Ext peri cranial bone surfaces 2. Mastoid process 3. Occipital condyles 4. Nasal septum, crista galli, floor of the nose 5. Orbital outline & inf surface of orbital plate of frontal bone. 6. Oblique line formed by ext surface of greater wing of sphenoid in the area of temporal fossa. www.indiandentalacademy.com
7. Sup surface of petrous portion of temporal bone 8. Lat surface of fronto sphenoid process of zygoma & zygomatic arch, including the key ridge 9. Cross section of zygomatic arch 10. Infra temporal surface of max in the area of tuberosity. 11. Body & rami, coronoid & condyles of mand when visible 12. As many dental units as possible www.indiandentalacademy.com
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1.Horizontal Ref planes Medial aspect of zygomatico frontal sutures Centres of zygomatic arch Medial aspect of jugal process One parallel to the Z plane through menton www.indiandentalacademy.com
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2. A mid sagittal ref line ( MSR ) - from Cg through ANS to chin
area
3. Mand morphology
analysis – Lt sided & Rt sided triangles – head of condyle (Co) to antegonial notch (Ag) & Menton ( Me ).
4. Volumetric comparision – Condylion (Co),
Antegonial notch (Ag), Menton(Me), www.indiandentalacademy.com
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Max-mand comparision of asymmetry Four lines – perpendicular to MSR, from Ag & J bilaterally Lines connecting Cg & J and Cg & Ag are drawn. Two pairs of triangles are formed that are compared for symmetry www.indiandentalacademy.com
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Linear asymmetry assessment The linear distances to MSR & differences in vertical dimension of the perpendicular projections of bilateral landmarks are calculated for the landmarks – Co, Nc, J, & Ag. www.indiandentalacademy.com
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Frontal vertical proportion analysis
Ratios of dental & skeletal analysis are made along the Cg – Me line U facial R – Cg-ANS:Cg-Me L facial R – ANS-Me:Cg-Me Max R – ANS-A1:ANS-Me Total Max R – ANS-A1:Cg-Me Mand R – B1-Me:ANS-Me Total Mand R – B1-Me:Cg-Me Max-Mand R – ANS-A1:B1:Me www.indiandentalacademy.com
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The comprehensive frontal asymmetry analysis consists of all data described above The summary frontal asymmetry analysis includes only the construction of horizontal planes, Mand morphology analysis, Max-Mand comparision of asymmetry www.indiandentalacademy.com
The surgical treatment objective It is an essential two dimensional tool in the surgical orthodontic correction of dento facial deformities. The purpose of STO 1. To establish pre surgical goals. 2. To develop an accurate surgical objective that will achieve the best functional & esthetic result www.indiandentalacademy.com
Two phases
;
1. The initial STO 2. The final STO
1 – It is a pre treatment evaluation to determine orthodontic & surgical goals 2 – It is done after dental decompensation, just prior to surgery to determine the exact vertical & AP skeletal and soft tissue changes www.indiandentalacademy.com
Changes in ST associated with surgical procedures Mand advancement – 100% relative to bone at pog & labio mental fold. - L lip – 60-70% with incisor . Mand set back – 90% change at chin, labio mental fold & L lip. Max set back – Nose-no effect - base of U lip – 20% of point A - U lip – 60% of incisor - NL angle – ↑ 1.2°/mm www.indiandentalacademy.com
Mand set back + Max advancement –
similar to combination of both separately.
Max superior repositioning -
Nose – base & tip - up by 20% U lip – 20 – 40 % shortening L lip – rotates 1:1 with mand
Mand sub apical ( advancement ) -
L lip forward by 60% while ST of chin remained stable. LM fold will ↓ in prominence www.indiandentalacademy.com
Mand sub apical ( set back ) L lip – post by 75% ST at chin – relatively unchanged LM fold - ↑ prominence Mand sub apical – Inf repositioning ST change will depend on the AP dento alveolar change www.indiandentalacademy.com
Single jaw STO
1. Draw initial tracing with orientation reference marks 2. Trace on a second sheet – PM extd 3. Vertical Ref line – perpendicular to OP & tangent to mesial of 2 nd PMs. 4. 3 rd sheet – draw anchor segments with OP & slide tracing ant till vertical Ref line – mesial of ext space. Now trace ant changing its inclination depicting a controlled tipping www.indiandentalacademy.com
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5. Two +’s – 35mm-C & 25mm-M 6. Three Ref planes 7. Additional horizontal Ref line 8. Mand cut out is rotated around center of condyle – L ant 2 mm above new position of U ant 9. Max and max teeth in separate cut out – re positioned superiorly & fixed 10. Final sheet – altered skeletal tissue along with soft tissue is traced www.indiandentalacademy.com
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Double jaw STO
1. Draw the initial tracing with orientation Ref marks. 2. Draw on a 2 nd sheet – PM extd. 3. Vertical Ref line – tangent to mesial of U-2-PM & distal of L-C 4. Trace U-post and slide tracing till vert Ref line – mesial of ext space & trace ant depicting controlled tipping 5. Trace L-ant & slide distally….. www.indiandentalacademy.com
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6. 3 rd sheet – trace decompensated hard tissue with soft tissue remodelling 7. With the current overjet & ceph values calculate sagital alteration of the jaws needed 8. Three Ref lines for the Max & Mand 9. With OP & Ref line as guide, slide the Max & Mand cut outs separately 10. Final sheet – trace the altered hard tissue with soft tissue remodelling www.indiandentalacademy.com
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The aging of facial features Formby et al – AJO 1994 – 18-42 yrs Males – 1. Profile straightened & lips more retrusive 2. Nose - ↑ed in all dimensions 3. ↑ed soft tissue thickness at pog 4. ↓ed U lip thickness & ↑ed L lip thickness www.indiandentalacademy.com
Females – 1. Profile did not straighten & lips did not become more retrusive 2. Nose ↑ed in all dimensions 3. ↓ed soft tissue thickness at pog. 4. ↓ed U lip thickness & ↑ed L lip thickness www.indiandentalacademy.com
Nasal changes – the nasal tip moved ant & inf with age – “droop” Lip thickness – they became less prominent & were located more inf. Naso labial changes – with↓ in lip prom & lowering of nasal tip -↑ acute. Dental changes – to show less of upper incisor & more of lower incisor at rest & on smile www.indiandentalacademy.com
We only treat what we are educated to see. The more we see, the better the treatment we render our patients. www.indiandentalacademy.com
www.indiandentalacademy.com Leader in continuing dental education
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