pa ceph/ dental implant courses by indian dental academy

21-12-06

INDIAN DENTAL ACADEMYINDIAN DENTAL ACADEMYLeader in continuing Dental Education Leader in continuing Dental Education

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CONTENTSCONTENTS

Introduction.Technical Aspects.Different Head Positions.Exposure Conditions and Considerations.Skull Anatomy : Frontal and Posterior View .Radiographic Anatomy.Cephalograph Tracing Procedure.Structures Included in Postero-Anterior Cephalograph.Postero-Anterior Cephalometric Landmarks.Purpose Of Postero-Anterior Cephalometry.Uses and Limitations of Postero-Anterior Cephalometry.Bibliography.


INTRODUCTIONINTRODUCTION

Mal-occlusions and dento-facial deformities constitute three-Mal-occlusions and dento-facial deformities constitute three-dimensional conditions or pathologies. Orthodontic treatment dimensional conditions or pathologies. Orthodontic treatment requires comprehensive three- dimensional diagnostic requires comprehensive three- dimensional diagnostic examination but assessment of postero-anterior and basilar examination but assessment of postero-anterior and basilar cephalometric views are particularly important for dento-cephalometric views are particularly important for dento-alveolar and facial asymmetries; dental and skeletal crossbites alveolar and facial asymmetries; dental and skeletal crossbites and functional mandibular displacements. and functional mandibular displacements.

With the advent of cephalometric radiography, postero-anterior With the advent of cephalometric radiography, postero-anterior cephalometric projections and relevant analyses constitute an cephalometric projections and relevant analyses constitute an important adjunct for qualitative and quantitative evaluation of important adjunct for qualitative and quantitative evaluation of the dento-facial region.the dento-facial region.


TECHNICAL ASPECTSTECHNICAL ASPECTS

Equipment Equipment :: Head-holder or Cephalostat. Head-holder or Cephalostat. X-ray source.X-ray source. Cassette holder containing the film.Cassette holder containing the film.

Patient positioning:Patient positioning: Patient is positioned upright facing the film.Patient is positioned upright facing the film.

X-ray source: Connection between the X-ray source and Connection between the X-ray source and cassette holder containing the film should be rigid.cassette holder containing the film should be rigid.

Distance between X-ray source to patient:Distance between X-ray source to patient: 5 feet ( 152.4cm) 5 feet ( 152.4cm) For the postero-anterior projection, the distance is measuredFor the postero-anterior projection, the distance is measured to the earpost axis.to the earpost axis.


Different Head Positions:

Fixed Head Position:Fixed Head Position:

The patient is fixed in the head-holder with the help of two ear-The patient is fixed in the head-holder with the help of two ear-rods, and the patient’s head rests on the uppermost side of the rods, and the patient’s head rests on the uppermost side of the rods, which are inserted into the ear holes.rods, which are inserted into the ear holes.The Frankfort horizontal plane is parallel to the floor in order to The Frankfort horizontal plane is parallel to the floor in order to maintain all vertical dimensions.maintain all vertical dimensions.

Natural Head Position:Natural Head Position:

It is a standardized orientation of head, which is assumed by It is a standardized orientation of head, which is assumed by focusing on a distant point at eye level focusing on a distant point at eye level ( Moorrees, 1985)( Moorrees, 1985)..Reproducibility of the natural head position is approx. 2Reproducibility of the natural head position is approx. 200, which , which supports its use in Cephalometry.supports its use in Cephalometry.( ( Lundstrom and Lundstrom, Lundstrom and Lundstrom, 1992).1992). The ear rods are placed directly in front of the tragus so that The ear rods are placed directly in front of the tragus so that they lightly contact the skin, thus support the head bilaterally in they lightly contact the skin, thus support the head bilaterally in transverse plane.transverse plane. www.indiandentalacademy.comwww.indiandentalacademy.com

FIXED HEAD POSITION NATURAL HEAD POSITION FIXED HEAD POSITION NATURAL HEAD POSITION


Other techniques of head positioning:

According to Chierici ( 1981)According to Chierici ( 1981)::

Patient’s head should be positioned with the tip of the nose and Patient’s head should be positioned with the tip of the nose and forehead lightly touching the cassette holder. This head position forehead lightly touching the cassette holder. This head position helps evaluate craniofacial anomalies of upper face.helps evaluate craniofacial anomalies of upper face.

According to Faber ( 1985)According to Faber ( 1985)::

In cases of suspected significant mandibular displacement, the In cases of suspected significant mandibular displacement, the postero-anterior cephalogram should be taken with the postero-anterior cephalogram should be taken with the patient’s mouth slightly opened.patient’s mouth slightly opened.

This helps differentiate between functional mandibular This helps differentiate between functional mandibular displacement and dento-skeletal facial asymmetry. displacement and dento-skeletal facial asymmetry.


CHIERICI HEAD POSITION FABER HEAD POSITIONCHIERICI HEAD POSITION FABER HEAD POSITION


Exposure conditions and Considerations:

According to According to Manson- HingManson- Hing, 1985:, 1985: Film exposure depends on Film exposure depends on certain factors like:certain factors like:

Speed of the film.Speed of the film.Speed of the screens.Speed of the screens.Tube to film distance.Tube to film distance.Size of patient’s head.Size of patient’s head.Milli-amperage and kilo-voltage used in generating the X-ray Milli-amperage and kilo-voltage used in generating the X-ray beam.beam.The film-exposure time .The film-exposure time .

More exposure is necessary for postero-anterior cephalogams More exposure is necessary for postero-anterior cephalogams than for lateral views than for lateral views ( Enlow) .( Enlow) .


SKULL ANATOMY: FRONTAL VIEWSKULL ANATOMY: FRONTAL VIEW


SKULL ANATOMY: POSTERIOR VIEWSKULL ANATOMY: POSTERIOR VIEW


RADIOGRAPHIC ANATOMYRADIOGRAPHIC ANATOMY


CEPHALOGRAPH - TRACING PROCEDURECEPHALOGRAPH - TRACING PROCEDURE

The tracing of postero-anterior cephalogram is carried out by The tracing of postero-anterior cephalogram is carried out by placing the cephalogram in front of the examiner so that placing the cephalogram in front of the examiner so that patient’s right should be on the examiner’s left.patient’s right should be on the examiner’s left.

The tracing should include most of the important structures of The tracing should include most of the important structures of the upper, middle and lower anterior face and the posterior .the upper, middle and lower anterior face and the posterior .

Assess and compare where the structures have been identified Assess and compare where the structures have been identified in the current lateral cephalogram of the same patient.in the current lateral cephalogram of the same patient.

The tracing of Postero-anterior Cephalogram begins with the The tracing of Postero-anterior Cephalogram begins with the mid-line structures seen in the lateral cephalogram and should mid-line structures seen in the lateral cephalogram and should include the occipetal, parietal , frontal and nasal bones , the include the occipetal, parietal , frontal and nasal bones , the maxilla, the sphenoid bone and the symphysis of mandible maxilla, the sphenoid bone and the symphysis of mandible ( Broadbent, 1975)( Broadbent, 1975)..


Structures Included in the Postero-Anterior Structures Included in the Postero-Anterior Cephalogram Cephalogram


POSTERO-ANTERIOR CEPHALOMETRIC LANDMARKS POSTERO-ANTERIOR CEPHALOMETRIC LANDMARKS


PURPOSE OF POSTERO-ANTERIOR PURPOSE OF POSTERO-ANTERIOR CEPHALOMETRYCEPHALOMETRY

The postero-anterior cephalometry is useful as a diagnostic The postero-anterior cephalometry is useful as a diagnostic tool. It serves to provide:tool. It serves to provide:

Gross Inspection: Gross Inspection: It provides information about morphology,It provides information about morphology, shape and size of the skull, bone density, suture morphology.shape and size of the skull, bone density, suture morphology. It may help to detect pathology of hard and soft tissuesIt may help to detect pathology of hard and soft tissues

Description and Comparison:Description and Comparison: Postero-anterior cephalograms Postero-anterior cephalograms of two persons can be compared to describe the skull .of two persons can be compared to describe the skull .

Diagnosis: Diagnosis: It analyses the nature and origin of the problem, It analyses the nature and origin of the problem, thereby, providing the possibility of quantification andthereby, providing the possibility of quantification and classification.classification.

Treatment Planning: Treatment Planning: The diagnostic information obtainedThe diagnostic information obtained helps to decide comprehensive and precise treatment plan .helps to decide comprehensive and precise treatment plan .www.indiandentalacademy.comwww.indiandentalacademy.com

Growth assessment and evaluation of treatment results:

Postero-anterior cephalograms of a patient are taken at various Postero-anterior cephalograms of a patient are taken at various time intervals and are compared to each preceeding one .time intervals and are compared to each preceeding one .

The superimpositions are made on the external peripheral The superimpositions are made on the external peripheral cranial bone outline or on any of the reference horizontal cranial bone outline or on any of the reference horizontal planes.planes.

Interpretation of characteristics and relationships of various Interpretation of characteristics and relationships of various craniofacial structures can also assess growth . craniofacial structures can also assess growth .


POSTERO-ANTERIOR CEPHALOMETRIC USES & POSTERO-ANTERIOR CEPHALOMETRIC USES & LIMITATIONSLIMITATIONS

Aims:

They evaluate craniofacial skeleton by means of linear absolute They evaluate craniofacial skeleton by means of linear absolute measurements of:measurements of:

Width or height.Width or height.AnglesAnglesRatios.Ratios.Volumetric Comparison.Volumetric Comparison.


Uses:Different structures of cranio-facial complex can also be Different structures of cranio-facial complex can also be analysed using qualitative methods.analysed using qualitative methods.

A postero-anterior cephalogram evaluates the verical, A postero-anterior cephalogram evaluates the verical, transverse and sagittal dimensions of different structures.transverse and sagittal dimensions of different structures.

Different structures can be evaluated w.r.t their vertical Different structures can be evaluated w.r.t their vertical dimension, position and proportionality.dimension, position and proportionality.

Vertical asymmetry can be easily detected by connecting Vertical asymmetry can be easily detected by connecting bilateral structures, drawing transverse planes, and by bilateral structures, drawing transverse planes, and by observing their relative orientationobserving their relative orientation..( Sollar, 1947; Proffit,1991).( Sollar, 1947; Proffit,1991).

The use of ratios in postero-anterior cephalogram can help The use of ratios in postero-anterior cephalogram can help compare different persons or groups whose radiographs have compare different persons or groups whose radiographs have been taken with uncontrolled enlargement of different structures been taken with uncontrolled enlargement of different structures of skull on X-ray film of skull on X-ray film ( Athanasiou et al, 1992).( Athanasiou et al, 1992).www.indiandentalacademy.comwww.indiandentalacademy.com

Limitations:

Precise linear measurements on postero-anterior cephalograms Precise linear measurements on postero-anterior cephalograms may be misleading. eg. The apparent distance will be affected may be misleading. eg. The apparent distance will be affected by a tilt of the head in the head holder.by a tilt of the head in the head holder.

Angular measurements can also be influenced in an Angular measurements can also be influenced in an uncontrolled manner.uncontrolled manner.

Diagnostic interpretation of ratios for clinical applications in Diagnostic interpretation of ratios for clinical applications in individual cases is difficult.individual cases is difficult.


BIBLIOGRAPHYAthanasios E Athanasiou and Aart JW Van der Meij :Athanasios E Athanasiou and Aart JW Van der Meij :

Orthodontic Cephalometry , Mosby-Wolfe Publications,1997 , Orthodontic Cephalometry , Mosby-Wolfe Publications,1997 , 3 3rdrd edn. , 141-161. edn. , 141-161.
