Introduction:Introduction:

Periapical radiograph is a type of Intra oral view in which the film is placed inside patient’s mouth and radio graphed using various techniques. . (Bisected angle, paralleling. .) The interpretation of radiographs plays an important role in the dental office. Several abnormalities are diagnosed solely by or with help of radiographs. For this reason the training in the interpretation of dental radiographs plays an import-ant role in the curriculum of dental students and hygienists. Primarily a thorough knowledge of the anatomy of upper and lower jaws is required. However, more is needed to interpret the radiographic images. A radiographic image is not just determined by the anatomical landmarks but also for instance by the direction of the x-ray beam. Due to a different projection angle of the x-ray beam anatomical structures can be displaced relative to each other. Students do need much practicing to get familiar with the normal anatomy at dental radiographs. At most dental schools in small student classes’ attention is paid to this subject. At the Dental School in Amsterdam students follow a practical course in making radiographs after their theoretical training is completed. Parallel to or before this course they have to take the CAI program on anatomical landmarks.

Peiapical Films Show. . Teeth Dental Germ

Tooth Consists of: Enamel(RO) Dentine(RO but less than enamel) Cementum(RO & Similar density to dentine) Pulp chamber & root Canals (RL)

Investing Structures Are: Cancellous Bone (Mixed RO & RL) Lamina Dura (RO) . . Normally it appears surrounding and parallel to root of tooth as RO line . . Periodontal Membrane Space Is The RL between Then . . It Should Be Of Uniform Thickness Normally Cortical Crest (RO) . . .Anteriorly It In Knife Edge Appearance

Posteriorly . . Flattened

RO=Radio opaqueRL=Radiolucent

BY Mahmoud El Masry-Dentistry-MSA University-2007

An Exact Technique Should Be Followed In Order To Produce A Radiograph Of Highest Possible Quality. . In Order To Be Able To Differentiate Between Normal And Abnormal structures . . .

Normal Maxillary Anatomical Landmarks:Normal Maxillary Anatomical Landmarks:

1-Anterior Region:1-Anterior Region:Radolucent Structures:

Nasal Fossa:

W Shaped Radiolucency . . . May Be MisInterpretated As Soft Tissue Tumor . . .To Make Sure It Is Nasal Fossa use Shift Skitch TechniqueIf Lesion Persists In Place : It Is Pathosis If Changes its Position: It Is Nasal Fossa

Incisive Foramen:

It is the opening in the midline of the palate just posterior to the central incisors. it gives passage to the nasopalatine artery and nerve .It should not be misdiagnosed As Dental Infection Or Cyst.

BY Mahmoud El Masry-Dentistry-MSA University-2007

Median Palatine Suture:

is the line down the center of the maxilla where embryonic palatal shelves joined at the midline to form the hard palate.It Should Not be misdiagnosed As fracture line nor fistulous tract . . .To diffrentiate . . .

Fracture line will be acoompaigned by history of trauma, it will be irregular RL Line, Will not be bordered By 2 RO Lines . . .Fistulous tract: by applying RO material through the lesion . . . the tortuous course of the tract can be observed

Incisive Fossa:

Also Called Canine Fossa . . And It Is the indentation between the roots of the central and lateral incisors, and the canine fossa is between the roots of the lateral incisor and canine.It should not be Misdiagnosed As pathological condition. . If So Radiograph the other side for comparison. .

Nasopalatine Canals:

BY Mahmoud El Masry-Dentistry-MSA University-2007

If Exaggerated vertical Angle is used they may appear as projections of maxillary Incisors . . .

Rdiopaque Structures:

Median Nasal Septum:

It is the thin wall of bone in the midline of the face that separates the right and left nasal fossae. . In Some cases unusual density may denote supernumerary tooth, mesiodens, or a retained root . . . .

Anterior Nasal Spine:

It is the triangular protuberance of bone that extends forward from the inferior aspect of the nasal cavity at the midline. . .

BY Mahmoud El Masry-Dentistry-MSA University-2007

It Should Not Be MisInterpretated As remaining root, Odon tome , Impaction, Foreign Body . . .

Nasal Turbinates:

Cartilaginous radiopacity that may appear on anterior maxillary radiographs is the inferior conch or inferior nasal turbinate. There are actually three turbinates on each side of the nasal antrum; however, only the most inferior of these is routinely projected onto the periapical view of the incisor region.

Nasal Cartilage:

It is the soft tissue of the tip of the nose. .It Appears as RO Shadow superimposed over incisors’ Roots . . It Is Uniform Opacity With Sharp Borders. .

BY Mahmoud El Masry-Dentistry-MSA University-2007

2-Canine Region:2-Canine Region:

Radolucent Structures: Nasal Fossa (Discussed

Before)

Incisive Fossa (Discussed Before)

Maxillary Sinus:

It Appears Better In Premolar Molar Region. .

Rdiopaque Structures:

They Appear AS Inverted Y Shape Of RO Lines Separating Two RL Areas( Nasal Cavity And Maxillary Sinus)Called Inverter Y Shape Of Innus . . .

BY Mahmoud El Masry-Dentistry-MSA University-2007

Nasal Fossa

Maxillary Sinus

Incisive Fossa

Inverted Y Shape Of Innus

3-Premolar Molar Region:3-Premolar Molar Region:

Radolucent Structures:

Maxillary Sinus:

It is the most important structure in the premolar-molar It is the most important structure in the premolar-molar region.region.

It occupies the greater part of body of maxilla and appears asIt occupies the greater part of body of maxilla and appears as RL Area.RL Area.

It is not completely visualized in periapical view.It is not completely visualized in periapical view.It extends by pneumatization and limited by roots of teeth. .It extends by pneumatization and limited by roots of teeth. .The RO line represents the floor of sinus and it is in close The RO line represents the floor of sinus and it is in close

proximity to roots of premolars and molars . . proximity to roots of premolars and molars . .

It should not be misdiagnosed as cyst or other pathosis . .It should not be misdiagnosed as cyst or other pathosis . .Differentiation is done by:Differentiation is done by:

Normally lamina dura should be intactNormally lamina dura should be intact Teeth are vitalTeeth are vital Symmetrical appearance in both sides Symmetrical appearance in both sides

of faceof face It is air filled (clear radilucency)It is air filled (clear radilucency) Clear marginsClear margins

Otherwise it is pathosis . . . . . . .Otherwise it is pathosis . . . . . . .

Rdiopaque Structures:

Malar Bone:

BY Mahmoud El Masry-Dentistry-MSA University-2007

It Is where Zeugmatic Bone Attach To Maxilla …It Appears As Well Defined RO Area super Imposed over Maxillary Molar Roots. .

So Interpretation of this view is difficult . . .

But effort may be exerted and different angulations may be used to shift this zygomatic shadow. .

It may be misdiagnosed as impacted teeth or foreign bodies

Radiolucent structures:

oHamular Notch:It Is found between hamular process and maxillary tuberosity . . .

Radiopaque Structures:

oMaxillary Tuberosity:

BY Mahmoud El Masry-Dentistry-MSA University-2007

It Is where Zeugmatic Bone Attach To Maxilla …It Appears As Well Defined RO Area super Imposed over Maxillary Molar Roots. .

So Interpretation of this view is difficult . . .

But effort may be exerted and different angulations may be used to shift this zygomatic shadow. .

It may be misdiagnosed as impacted teeth or foreign bodies

4-Regions Posterior To Upper Third Molar . .

Hamular Process

Hamular Notch

Maxillary tuberosity

It appears radiographically. The maxillary tuberosity is the rounded bony eminence just posterior to the most distal molar, at the distal end of the maxillary alveolar ridge. This photograph shows both tuberosities well. This inferior view shows the area of the tuberosities, as indicated by the pencil. It is a little difficult to see the rounded shape of the maxillary tuberosity from this view. This periapical radiographic projection of the maxillary second molar region clearly demonstrates the maxillary tuberosity area.It Contains Spongy one although It Is The Hardest Structure In Maxilla. .It May be pneumatized by extension of maxillary sinus resulting in a very fragile tuberosity . . . . ..

oHamular Process:

It is Finger Like Projection Of Bone Distal To The Tuberosity. .It Is the Hamular process Of The Sphenoid bone . . .

o Coronoid Process Of Mandible:

It May Appear When The Mouth Is Opened as triangular Projection Located At The Area Of The Tuberosity . . .

BY Mahmoud El Masry-Dentistry-MSA University-2007

Normal Mandibular Anatomical Landmarks:

1-Anterior Region:

RadioLucencies Radiopacities

Lingual Foramen Genial Tubercles

Interdental Nutient Canals Mental Ridge

1)-GENIAL TUBERCLES:

BY Mahmoud El Masry-Dentistry-MSA University-2007

The genial tubercles are small bony spines found on the lingual aspect of the mandible adjacent to the midline at the attachment of the geniohyoid and genioglossus muscles.

In this close-up view you can clearly see the genial tubercles on the lingual midline. Notice also the small opening right in the middle of the tubercles. This is called the lingual foramen, an opening in the lingual midline of the mandible for a small vessel. This illustration demonstrates the function of the genial tubercles, or mental spines as they are sometimes called, as a locus for the attachment of the geniohyoid and genioglossus muscles. This occlusal radiograph of an edentulous mandible depicts the genial tubercles as seen in an axial plane.

If you look closely here you can also discern the attached

2)-MENTAL RIDGE:

The mental ridges are elevated ridges of bone located along the anterior aspect of the mandible. The ridges are also known as the mental tubercles and fuse at the mid-line to form the mental protuberance, the anterior most aspect of the mandible. This periapical radiograph demonstrates the radiopaque margin of the mental ridges. Study these and compare the varying appearance of these landmarks.

BY Mahmoud El Masry-Dentistry-MSA University-2007

The genial tubercles are small bony spines found on the lingual aspect of the mandible adjacent to the midline at the attachment of the geniohyoid and genioglossus muscles.

In this close-up view you can clearly see the genial tubercles on the lingual midline. Notice also the small opening right in the middle of the tubercles. This is called the lingual foramen, an opening in the lingual midline of the mandible for a small vessel. This illustration demonstrates the function of the genial tubercles, or mental spines as they are sometimes called, as a locus for the attachment of the geniohyoid and genioglossus muscles. This occlusal radiograph of an edentulous mandible depicts the genial tubercles as seen in an axial plane.

If you look closely here you can also discern the attached

3)-Lingual Foramen:

Discussed before. .

4)-Interdental Nutrient Canals:

They Contain Blood Vessels And Nerves That Supply teeth And Investing Structures . . They Appear as RL Lines of uniform width and sometimes exhibit RO margins . . .they are clearly seen In Patients with edentulous Mouth. .They Should Not Be MisInterpretated As Fracture Lines . .If so They will be irregular lines with previous history of trauma . . .

Radiographically, nutrient canals appear as uniform thin radiolucent lines. The margin of these lines is often slightly more radiopaque than the adjacent bone.

BY Mahmoud El Masry-Dentistry-MSA University-2007

Sometimes these canals can be seen running toward the apices of teeth as accessory branches of the inferior alveolar canal. In this instance the canals contain both blood vessel and nerve supplies to the tooth and are termed accessory canals.

Nutrient canals are most noticeable when they appear between roots or within edentulous areas where they lie against the bony wall and reduce the thickness of bone in the area of the vessel.

2-Premolar Region:

The Most Important Structure In This Area Is Mental foramen . . . . .

BY Mahmoud El Masry-Dentistry-MSA University-2007

The mental foramen is an opening in the facial aspect of the mandible in the premolar area.

This photograph of the mandible demonstrates the usual location of the mental foramen. We can see that its position will cause it to appear radiographically near the apex of the lower second premolar. As this drawing demonstrates, the mental foramen provides the exit point from within the mandible for the mental nerve, as well as the inferior alveolar artery.

In periapical radiographs the mental foramen appears as a rounded radiolucency in the apical region distal to the canine and mesial to the first molar. Often it is not as distinct as some other landmarks, but recognizing it is important. Sometimes the mental foramen will be superimposed on the apex of a premolar, and will give the appearance of pulpal pathology.

The best way to differentiate periapical disease from the mental foramen is to identify the periodontal membrane space to see if it is confluent with the radiolucent opening.

If the apical radiolucency is due to periapical pathology, the periodontal membrane will appear to join the radiolucency, but if the lucent area is due to the mental foramen, then the periodontal membrane space will remain intact, and can be distinctly followed around the tooth apex. Notice the difference in appearance of the pathology at the apex of the distal root of the first molar and the radiolucency of the mental foramen which superimposes on the apex of the second premolar.

BY Mahmoud El Masry-Dentistry-MSA University-2007

Left Arrows Are Mental Foramen . . While right Arrows Are Apical Pathosis

3-Molar Region:

Mandibular Canal:

The inferior alveolar nerve and artery pass through the mandible through a structure called the mandibular canal. The mandibular canal extends from the mandibular foramen, on the lingual aspect of the ramus, through the body of the mandible under the roots of the molar teeth. The canal terminates at the mental foramen, where the mental nerve branches buccally through the cortex to enervate the soft tissues of the lower lip and chin area. The rest of the inferior alveolar nerve extends mesially to enervate the canines and incisors. This anterior extension of the inferior alveolar canal is called the anterior loop. In this premolar radiograph, the mandibular canal is delineated by black arrows, the mental foramen by a white circle, and the anterior loop by white arrows. In this posterior lingual view of the mandible, you can clearly see the mandibular foramen, which is the proximal or posterior opening of the mandibular canal. This view illustrates the route followed by the mandibular canal from the lingual posterior to the facial anterior at the mental foramen. The mandibular canal appears radiographically as two roughly parallel radiopaque lines traversing the body of the mandible. In this radiograph you can see the mandibular canal clearly below the apicies of the molar teeth. Look closely to distinguish the radiolucent mental foramen, at the anterior extent of the canal.You'll frequently see the mandibular canal in periapical radiographs of the body of the posterior mandible. The tube-like nature of this structure gives it the characteristic radiographic appearance seen here. The radiographic appearance of the mandibular canal is due to the fact that the X-ray beam passes through the denser cortices of the outer edges of the canal to produce radiopaque lines, while the center, without so much superimposition of bone retains a radiolucent characteristic.

BY Mahmoud El Masry-Dentistry-MSA University-2007

SubMandibular Fossa:

BY Mahmoud El Masry-Dentistry-MSA University-2007

Directly below the internal oblique ridge is a depression in the lingual aspect of the mandible called the submandibular fossa. This concavity is visible radiographically since the thickness of bone is substantially reduced in this area. The submandibular fossa is the location of the submandibular salivary gland, as you can see from this drawing. The radiolucent appearance of the submandibular fossa is well demonstrated in this periapical molar view. It is important to recognize this as normal anatomy because this is another feature which may resemble pathology such as tumors or cysts. When a steep upward projection geometry is used to produce the periapical image, the shape of the internal oblique ridge produces a distinct opaque band that delineates the superior border of the submandibular fossa. When a flatter vertical projection geometry is used the submandibular fossa appears as a dark area with indistinct borders as seen in this image.

Lower Border Of Mandible:

The lower border of the mandible is the thick cortical plate that forms the lower edge of the mandible. The solid thickness of bone along the inferior border of the mandible is seen in the radiograph as a uniform wide radiopaque band at the margin of the mandible.

Int O R:

BY Mahmoud El Masry-Dentistry-MSA University-2007

The internal oblique ridge (or mylohyoid line) is an eminence of bone extending along the lingual aspect of the mandible. It serves as the attachment point for the chief muscle of the mouth floor, the mylohyoid muscle. This drawing shows the location and direction of mylohyoid muscle, which is attached to the mandible at the internal oblique ridges.Radiographically the internal oblique ridge appears as a radiopaque band extending from the terminal molar region to the premolar area, as seen in this periapical projection. Note that part of the mandibular canal is visible just below the mylohyoid line and is often superimposed on the image of the internal oblique ridge.

Ext O R:

The CAI Program

The program consists of 4 lessons. Lesson 1 deals with the anatomical landmarks in the lower jaw. The upper jaw is anatomically and radiographically more complicated and the subject is therefore covered in three lessons. Each lesson consists of a number of questions, mainly about the radiographs shown in a separate window on the screen. See figure 1. Three different types of questions are being used: Multiple choice questions, a type of question with which the student is familiar from his exams. Furthermore questions where short open answers are required. In this case mostly the correct name of the landmark is asked for and finally a type where the student has to use the mouse and click at a specific area in the radiograph. This type of question or command is particularly attractive as this comes closest to 'reality' in interpreting dental radiographs, pointing to specific anatomic landmarks. Next to each answer feedback is given where the (in)correctness of the answer is explained. In all cases, also before answering the question, the student can ask for support or help. In that case hints are given (not the answers) and often a drawing is shown with the path of the x-rays relative to the skull. See also figure 2. It helps the student in finding the correct answers. Also a reference to a book is possible. The program keeps track of the results of the students initial answers. During or at the end of the session an overview can be obtained of correct and incorrect answers. It is possible to jump to each individual question or to skip questions. The basic version of the program originates from 1988 when a DOS-version was developed. At that time a computer monitor for the texts and a tv-monitor for the images were used. The program was expanded and converted to a Windows environment in 1994 using Authorware Professional a an authoring tool.

BY Mahmoud El Masry-Dentistry-MSA University-2007

The external oblique ridge is a ridge of bone located along the facial of the mandible, which extends from the superior aspect of the posterior body of the mandible down to the necks of the molar teeth. It runs in the same direction as the internal oblique ridge, but is located on the facial, or external surface of the mandible. The external oblique ridge serves as the attachment point for the buccinator muscle, as demonstrated in this drawing. The next two periapical projections demonstrate the radiographic appearance of the external oblique ridge. To distinguish radiographically between the internal and external oblique ridges, note that the external ridge is always superior to the internal oblique ridge. In this image the external oblique ridge is denoted by white arrows while the internal oblique ridge is demarcated by black arrows.

In total more than 200 images (radiographs and drawings) are available in the program. 75 Megabyte storage is required. The development of the program was a cooperation of two teachers in dental radiology, an arts designer, a programmer and an expert in educational matters.

Educational environment

A practical course, where this CAI program forms part of, is given 12 times a year for small groups of eight students. Before the introduction of the CAI program approx. 8 hours were needed for group discussion on the interpretation of the dental radiographs. Primarily the frequent repetition of the course was reason to develop this CAI program. More time became available for patient activities. In the new setting less than four hours are needed for the traditional instruction. Separately 2 hours are made available for students to follow the CAL program. The students are advised to do this before start of the clinical course. The function of the program is primarily to offer additional individual practice and drill facilities. A major advantage of the program is the reduction of 'contact' hours for the teacher and all students are faced individually with the educational materials. Smooth operation of the CAI programs requires a 486 processor and 8 Mb internal memory, a SuperVGA screen (1024x786 dots) and a dual speed CD-Rom drive. The Dental School in Amsterdam has 10 of these units available for students. The student can take this course at any time upon availability of the units and can repeat this as often as desired. As during their clinical activities, sometimes appointments are being canceled by patients the students can fill the gaps in their regular program. Dental hygienists also make use of these CAI programs. Although initially not intended for this group it appears to fit in well in their curriculum. In principle dental anatomy and radiographic landmarks are elementary parts of the curriculum which do not change by newer views or insights.

Experience

For a period of 6 months a log file was used to register the length of each CAL session and the answers. The incorrect answers were used to adjust irregularities and to add additional feed back. The average student needs 2 and a half hours to run the complete content of the lessons. In general students do appreciate the program very much. Students can handle the program without extensive explanations. They consider the contents interesting and the questions and explanations are in general clear. The level of the program was considered good by 95% of the students. It appeared that 56% of the student obtained a reasonable amount of new information and an additional 40% of the students learned very much. A negative comment of the students was that after a number of mishits the correct answer was not made available. Maybe this will be changed in the future.

Conclusions

BY Mahmoud El Masry-Dentistry-MSA University-2007

The program seems to meet the expectations. Students can exercise at a moment convenient for them and at a speed according to their skills. In particular the commands where they have to click at specific areas in the radiographs are successful as this approaches the clinical practice most. According to the teacher students now have a higher entrance level than before the existence of the program. Students can find time to take the course at a time convenient to them. Teachers save several teaching hours va year, time which now can be used for patient related programs

BY Mahmoud El Masry-Dentistry-MSA University-2007