Principles and Techniques of Biopsy

It is important to develop a systematic approach in evaluating a patient with a lesion in the Oral and Maxillofacial region.

These steps include :

• A detailed health history
• A history of the specific lesion
• A clinical examination
• A radiographic examination
• Laboratory investigations
• Surgical specimens for histopathologic evaluation

Health History

An accurate health history may disclose predisposing factors in the disease process or factors that affect the patients management.

Up to 90% of systemic deseases can be discovered through history taking.

The same can be true of oral lesions when one is familiar with the natural progression of the more common disease processes.

Medical conditions that warrant special care include:

• Congenital heart defects
• Coagulopathies
• Hypertension
• Poorly controlled diabetics
• Immunocompromised patients

History of the Lesion

Questions to Ask

• Duration of the lesion
• Changes in size and rate of change
• Changes in the character of the lesion.
• Lump to ulcer, etc
• Associated systemic symptoms:               

• fever                                                                                                    
• nausea                                                                                
• anorexia

More Questions to Ask

• Pain
• Abnormal sensations
• Anesthesia
• A feeling of swelling
• Bad taste or smell
• Dysphagia
• Swelling or tenderness of adjacent lymph nodes
• Character of the pain if present

Historical Reasons for the Lesions:

Trauma to the area

Recent toothache

Habits

Clinical Examination

• The clinical examination should always include when possible:  
• Inspection                                                                                          
• Palpation                                                                                            
• Percussion                                                                                         
• Auscultation

Clinical Evaluation

• The anatomic location of the lesion/mass
• The physical character of the lesion/mass
• The size and shape of the lesion/mass
• Single vs. multiple lesions
• The surface of the lesion
• The color of the lesion
• The sharpness of the boundaries of the lesion
• The consistency of the lesion to palpation
• Presence of pulsation
• Lymph node examination

Radiographic Examination

The radiographic appearance may provide clues that will help determine the nature of the lesion.

A radiolucency with sharp borders will often be a cyst

A ragged radiolucency will often be a more aggressive lesion

Radiopaque dyes and instruments can help differentiate normal anatomy

Laboratory Investigation

Oral lesions may be manifestations of systemic disease.

If a systemic disease is suspected it should be pursued.

These include:

• Tumor of hyperparathyroidism
• Padgets disease
• Multiple myeloma                          
• Determination of serum calcium,phosphorus, and alkaline phosphatase and protein can be very useful in excluding certain pathological processes.

Indications for Biopsy

• Any lesion that persists for more than 2 weeks with no apparent etiologic basis
• Any inflammatory lesion that does not respond to local treatment after 10 to 14 days.
• Persistent hyperkeratotic changes in surface tissues.
• Any persistent tumescence, either visible or palpable beneath relatively normal tissue.
• Inflammatory changes of unknown cause that persist for long periods
• Lesion that interfere with local function
• Bone lesions not specifically identified by clinical and radiographic findings
• Any lesion that has the characteristics of malignancy

Characteristics of lesions that raise the suspicion of malignancy.

• Erythroplasia- lesion is totally red or has a speckled red appearance.
• Ulceration- lesion is ulcerated or presents as an ulcer.
• Duration- lesion has persisted for more than two weeks.
• Growth rate- lesion exhibits rapid growth
• Bleeding- lesion bleeds on gentle manipulation
• Induration- lesion and surrounding tissue is firm to the touch
• Fixation- lesion feels attached to adjacent structures

What is a Biopsy?

Biopsy is the removal of tissue for the purpose of diagnostic examination. 

Types of Biopsy

1. Oral cytology
2. Aspiration biopsy
3. Incisional biopsy
4. Excisional biopsy
5. Needle biopsy

Oral Cytology

Developed as a diagnostic screening procedure to monitor large tissue areas for dysplastic changes.

Most frequently used to screen for uterine cervix malignancy

May be helpful with monitoring postradiation changes, herpes, pemphigus.

The Disadvantage of oral cytological procedures include:

Not very reliable with many false positives.

Expertise in oral cytology is not widely available

The lesion is repeatedly scraped with a moistened tongue depressor or spatula type instrument.  The cells obtained are smeared on a glass slide and immediately fixed with a fixative spray or solution.

Aspiration Biopsy

Aspiration biopsy is the use of a needle and syringe to penetrate a lesion for aspiration if its contents.

Indications:                       

To determine the presents of fluid within a lesion

To a certain the type of fluid within a lesion        

When exploration of an intraosseous lesion is indicated               

Aspiration

An 18 gauge needle on a 5 or 10 ml syringe is inserted into the area under investigation after anesthesia is obtained.

The syringe is aspirated and the needle redirected if necessary to find the fluid cavity.

Incisional Biopsy

An incisional biopsy is a biopsy that samples only a particular portion or representative part of a lesion.

If a lesion is large or has different characteristics in various locations more than one area may need to be sampled

Indications:

Size limitations

Hazardous location of the lesion                                              

Great suspicion of malignancy

Technique:

Representative areas are biopsied in a wedge fashion.

Margins should extend into normal tissue on the deep surface.

Necrotic tissue should be avoided.                                         

A narrow deep specimen is better than a broad shallow one.     

Excisional Biopsy

An excisional biposy implies the complete removal of the lesion.

Indications:                                                       

Should be employed with small lesions.  Less than 1cm 

The lesion on clinical exam appears benign.        

When complete excision with a margin of normal tissue is possible without mutilation.                                                                                                 

Excisional Biopsy

Technique:                        

The entire lesion with 2 to 3mm of normal appearing tissue surrounding the lesion is excised if benign. 

Principles of Surgery                                     

Anesthesia

• Block anesthesia is preferred to infiltration
• When blocks are not possible distant infiltration may be used
• Never inject directly into the lesion

Tissue Stabilization

• Digital stabilization
• Specialized retractors/forceps
• Retraction sutures
• Towel Clips

Hemostasis

• Suction devices should be avoided
• Gauze compresses are usually adequate
• Gauze wrapped low volume suction may be used if needed

Incisions

• Incisions should be made with a scalpel.
• They should be converging
• Should extend beyond the suspected depth of the lesion
• They should parallel important structures
• Margins should include 2 to 3mm of normal appearing tissue if the lesion is thought to be benign.
• 5mm or more may be necessary with lesions that appear malignant, vascular, pigmented, or have diffuse borders.

Handling of the Tissue Specimen

• Direct handling of the lesion will expose it to crush injury resulting in alteration the cellular architecture.

Specimen Care

• The specimen should be immediately placed in 10% formalin solution, and be completely immersed.

Margins of the Biopsy

• Margins of the tissue should be identified to orient the pathologist.  A silk suture is often adequate.  Illustrations are also very helpful and should be included.

Surgical Closure

• Primary closure of the wound is usually possible 
• Mucosal undermining may be necessary 
• Elliptical incision on the hard palate or attached gingiva may be left to heal by secondary intention.

Biopsy Data Sheet

• A biopsy data sheet should be completed and the specimen immediately labeled.  All pertinent history and descriptions of the lesion must be conveyed.
• Intraosseous and Hard Tissue Biopsy
• Intraosseous lesions are most often the result of problems associated with the dentition.

Indications for Intraosseous Biopsy

• Any intraosseous lesion that fails to respond to routine treatment of the dentition.
• Any intraosseous lesion that appears unrelated to the dentition.

Clinical Exam

• Palpation of the area of the lesion with comparison to the opposite side.
• Any radiolucent lesion should have an aspiration biopsy performed prior to surgical exploration.
• Information from the aspiration will provide valuable information about the lesion.

• Solid
• Fluid Filled                                                                                                          
• Vascular                                              
• Without Contents           

Principles of Surgery

• Mucperiosteal flaps should be designed to allow adequate access for incisional/excisional biopsy.
• Incisions should be over sound bone
• Cortical perforation must be considered when designing flaps
• Flaps should be full thickness
• Major neurovascular structures should be avoided
• Osseous windows should be submitted with the specimen
• Osseous preformations can be enlarged to gain access
• Avoid roots and neurovascular structures
• The tissue consistency and nature of the lesion will determine the ease of removal
• Incisional biopsies only require removal of a section of tissue
• Soft tissue overlying the lesion should be reapproximated following thorough irrigation of the operative site.
• The specimen should be handled as previously described

Biopsy Results: What If ?

They don’t corroborate your clinical impression

Repeat the biopsy!!!     

Determine if the tissue was looked at by an Oral Pathologist      

The results show malignancy                     

When To Refer For Biopsy

When the health of the patient requires special management that the dentist feel unprepared to handle

The size and surgical difficulty is beyond the level of skill that the dentist feels he/she possesses

If the dentist is concerned about the possibility of malignancy

Biopsy in oral surgery

Interceptive Orthodontics

Definitions:

Any procedure that eliminates or reduces the severity of malocclusion in the developing dentition.

The aetiology of malocclusion could be:

1- Skeletal discrepancy

2- Soft tissue

3- local factors

4- Crowding and spacing

5- Displacements

Anterior Crossbite

Interceptive orthodontics

Maxillofacial Trauma-Lecture note with Powerpoint Presentation

Etiology and Incidence

• Multisystem injury 20-50%
• Nasal and mandibular fractures most common in community ED’s
• Midface and zygomatic injuries most common in Trauma centers
• 25% of women with facial trauma result of domestic violence
• Incidence of concomitant cervical spine injuries with facial fractures
• Older age, MVC and TBI-higher incidence
• Facial fractures-a distracting injury?
• Carotid artery injury
• Blindness may occur with facial fractures

(Watch the PowerPoint presentation to See the Images)

Emergency Management and Resuscitation

Airway

Most urgent complication-Airway compromise

Simple interventions first

No mandible?

Intubation

Avoid nasotracheal intubation

May not want RSI

Benzodiazepines

Ketamine

Etomidate

Be Prepared and Be Creative

Emergency Management and Resuscitation

Airway Management Options

• Awake intubation
• Laryngeal Mask Airway
• Fiberoptic intubation
• Lateral or semi-prone position
• Percutaneous transtracheal jet ventilation
• Retrograde intubation
• Cricothyroidotomy

Hemorrhage Control

Rarely develop shock from facial bleeding alone

Direct Pressure

LeFort Fractures

Nasal hemorrhage may require A&P packing

History

Vision

Teeth alignment

Abuse

Maxillofacial Trauma-Physical Exam

Inspection

Facial elongation

High grade LeFort Fracture

Asymmetry

Deformities and cranial nerve injury

Palpation

Tenderness

Step offs

Facial stability

Crepitus

Subcutaneous air

Cutaneous anesthesia

Periorbital and Orbital Exam

Perform early

Periorbital and Orbital Exam

Look for exophthalmos or enophthalmos

Pupil shape

Hyphema

Visual acuity

Entrapment signs

Raccoon sign

Bimanual Palpation Test

Penetrating Injuries

Occult globe penetration

Eyelid lacerations

Nose

Septal hematoma

CSF Rhinorrhea

Ears

Subperichondral hematoma

Hemotympanum

Battle sign

Oral and Mandibular Exam

Mandible deviation

Teeth malocclusion

Paresthesia

Tongue Blade Test

• 95% Sensitive
• 65% Specific

Maxillofacial Trauma-Imaging

Head, chest and abdominal trauma takes precedence

PE detects up to 90% of fractures

Plain Films

CT

• Orbital fractures
• 3D images available

Maxillofacial Trauma-Specific Fractures

Frontal Sinus/Bone Fractures

• Direct blow
• Frequent intracranial injuries
• Mucopyoceles
• Consult with NS for treatment, disposition and antibiotics

Nasoethmoidal-Orbital Injuries

• Lacrimal apparatus disruption
• Bimanual palpation if medial canthus pain
• CT face

Orbital Fractures

• Usually through floor or medial wall
• Enophthalmos
• Anesthesia
• Diplopia
• Infraorbital stepoff deformity
• Subcutaneous emphysema

Orbital Fissure Syndrome

• Fracture of the orbital canal
• Extraocular motor palsies and blindness
• If significant retrobulbar hemorrhage, may need cantholysis to save vision

Zygomatic Fractures

Tripod fracture

• Most serious
• Lateral subconjunctival hemorrhage
• Need ORIF

Arch fracture

• Most common
• Outpatient repair

Maxillary Fractures

• High-energy injury
• 100x gravity
• Malocclusion
• Facial lengthening
• CSF rhinorrhea
• Periorbital ecchymosis

Mandibular Fractures

• Second most common facial fracture
• Often multiple
• Malocclusion
• Intraoral lacerations
• Sublingual ecchymosis
• Nerve injury

Plain films

Panorex

CT

Open Fractures

Pen G or Cleocin

 

Maxillofacial trauma PowerPoint Presentation

Types of Facial Injuries and their indications for Referrals PowerPoint Presentation(PPT)

Le Fort Fractures

Types of Facial Injuries and Their indications for referrals-PowerPoint Presentation

Composite the ultimate material for minimally invasive dentistry(Hybrid Composites,Micro filled Composites,Nano filled composites)

Educational Objectives

Upon completion of this course, participants should be able to achieve the following:

• Understand what the three classification systems in composite materials and what their indications.

• Learn clinical tips for Class I and Class II direct posterior restorations.

• Learn layering techniques to build in dentinal lobes, incisal edge effects and incisal halos.

• Learn simple polishing techniques to create the appropriate finish and luster.

Introduction

Used in Class I, II and IV restorations in the posterior and anterior regions, composite resins represent an attractive restorative option for patients who desire minimally invasive treatment or cannot afford more costly indirect alternatives. Among the most versatile materials, composites might be used in direct restorations, build-ups, cements, diagnostic mock-ups, gingival stabilization, provisionals and prototypes. Although previous direct composite generations have demonstrated polymerization shrinkage and the potential for marginal leakage resulting in the development of secondary caries, their benefits today outweigh the risks, which can be avoided when proper materials and techniques are utilized. A viable solution to the problems of amalgam, including cusp fractures, increased rates of secondary caries and possible toxicity due to mercury content, has increased the demand for composite resins in recent years.

Composites

Conserving sound tooth structure and with the potential for tooth reinforcement, adhesively bonded composite restorations demonstrate aesthetically acceptable results. The least invasive and predictable restoration of teeth to normal form and function, tooth-colored composites provide patients and dentists with a cost-effective and long-lasting solution for a variety of indications.However, four parameters dictate an ideal composite material outcome:

• Mirror natural tooth structure in color and translucency.

• Strength to withstand function in high stress-bearing areas for the long term.

• Seamless or undetectable margins from restoration to tooth for the long term.

• Appropriate polish and luster that can be maintained throughout the life of the restoration.

Hybrids

Compared by the author to rocks with pebbles loaded between them, hybrids or microhybrids are heavy-loaded materials that display an average 1μ glass particle sizes and .04μ silica in resin.8,9 This class of materials demonstrates high strength and opacity similar to natural dentin and enamel. Less likely to chip, hybrids can provide strength in any of the functional areas and, through layering techniques, can mimic dentin and enamel morphology. A disadvantage, however, is that their polish is not long-lasting.

Microfills

Described as all pebbles and composed of an average 0.1μ glass particles in resin, microfills display high polishability that lasts for the long term.When compared to hybrids, microfills demonstrate a higher resistance to wear and a translucency similar to enamel. These materials also give dentists the ability to replace the color, translucency, polishability, wear resistance and surface texture of natural enamel. However, microfills lack the strength required for many of the functional areas and can be too translucent.

Nanofills (Nanohybrids)

A newer-class of composites, nanofilled materials display 20nm primary particle sizes, consisting of zirconia-silica nanoclusters and silica nanoparticles (0.01μ glass particles in resin). Because this material contains even smaller particles, it has the potential to maintain greater strength and long-term polishability.Therefore, according to the author’s analogy of rocks and pebbles, nanofilled composites would additionally have grains of sand. In this analogy, when wear does occur, only pebbles and grains of sand “pluck out” leading to more favorable mechanical and optical properties. Nanofilled composites also display opacity similar to natural enamel and dentin, with translucency similar to enamel.

Demonstrating high strength, nanofilled composites are less likely to chip in high stress areas.1 The only true disadvantage to nanofilled composites, however, is the lack of in-vivo long-term studies, since the material science is relatively new.When using the different types of composites, it is necessary to understand that both technique and material selection define the outcome. By using the proper composite, tints and opaquers, along with proper layering, customization and polishing, predictable restorative outcomes can be completed and maintained.

Aesthetics

Dentists must realize that there are many different characteristics of the teeth, which are key to understanding aesthetics, that need to be addressed during treatment planning. When recreating tooth shape, the line angle, outline form and profile must be considered, along with tooth proportions, which involves the width-to-length ratio. To develop proper symmetry, the tooth shape must be developed first, followed by the embrasures and contact point.

Another fundamental aspect of aesthetics, age and gender play important roles in the development of highly aesthetic and natural appearing restorations. For example, age should be a major consideration when building the central incisors, and gender should define the lateral incisors. Other aesthetic considerations should include the smile line, cant, tooth size, central dominance, axial inclination, reverse “S and S” line angles and the natural curvature of the dentition. The location and direction of the midline is also crucial to aesthetics and should be evaluated and developed prior to any preparation. Once the dentition is understood and a treatment plan developed, the facial characteristics of the patient and their skin tone must be evaluated. By doing so, harmony between the restorations and the patient’s facial features can be created to develop the best in aesthetics.

Basic Principles for Adhesive Dentistry

A rubber dam should always be used to isolate the preparation and stop contamination from blood and saliva. Rubber dams also provide the added benefit of preventing the patient from swallowing the potentially toxic mercury that is present in amalgam fillings. It is important to note that once removed, amalgam fillings should be disposed of properly. In 2007, the American Dental Association adopted “Best Management Practices for Amalgam Waste,” which include the voluntary use of amalgam separators. Additionally, the Environmental Protection Agency has been reviewing options for regulating the dental industry regarding mercury discharge, as well as for requiring the installation of amalgam separators.The author has an amalgam separator (DRNA ISO Certified BU10 Amalgam Separator, Dental CareWaste Management) in his office and encourages other practitioners to incorporate one in their practices also.

Adhesive Systems

Once rubber dam isolation is achieved, the preparation should be etched, primed and then bonded to provide the most predictable results.Of the adhesive systems available on the market today, total-etch, three-step systems are considered the “gold standard” and are the author’s preference for indirect restorations. These three-step systems come in two bottles and are indicated for use in all indirect and direct restorations. In comparison, a self-etching, two-step system, per the manufacturer, requires pre-etching on uncut enamel, essentially, from a technique standpoint, making a self-etching, two-step system a total-etch, three-step system.

Class-based Preparation and Placement

Class I

To begin preparation of Class I indications, previous restorations and any remaining decay are first removed. Bevels should not be used in these situations, and rounded line angles are required internally. An incremental filling technique must then be used when layering the new composite, being sure not to join the buccal-lingual walls. An example of this type of restorative procedure includes removing the decay and old restorations, then etching the dentin and enamel. The etchant is agitated while on the surface of the tooth and left for 15 to 30 seconds before being rinsed away. The dentin is then wet, followed by priming and bonding using a total-etch, one-bottle system. Multiple coats are placed and agitated before air-drying to remove the necessary contaminants (i.e., solvent).25 To seal the dentin and enamel, the bonding agent is light cured.

To build the restoration, the cuspal inclines are formed using a microhybrid or nanohybrid composite in appropriate shades and tints where desired. Each individual layer is light cured (ramp cured) through the tooth. The cuspal inclines are adjusted as necessary.

Class II

Like in Class I indications, the preparation for Class II restorations begins by removing amalgam or old composite and any remaining decay. Once again, no bevel is used, and rounded line angles are required. The enamel periphery ideally would demonstrate 0.5mm to 1.0mm of enamel in height and width at the gingival floor. Layering is similar to Class I restorations, with incremental filling without joining the buccal-lingual walls. For shading characteristics, 2+ shades of a microhybrid should be used, with incisal/translucent microhybrid or microfill layered over the restoration.

Today’s nanohybrid composites (Venus Diamond, Heraeus, South Bend, Illinois), however, can enable us to achieve such aesthetics with a single-layer composite material. To form the interproximal contact of Class II restorations, several options are available, including pre-wedge before the rubber dam is placed, a sectional matrix with proper wedging, and utilization of special instrumentation.An example of a clinical case involves first cutting out the old amalgam filling. The rubber dam is placed, all previous material and decay is removed, and the matrix is placed. The preparation is then etched for 15 to 30 seconds. After the etchant is rinsed away and the surface partially dried, the total-etch, one-bottle adhesive is applied to the preparation with agitation in multiple coats and, after 30 seconds, thinned with air to blow off the necessary contaminant (i.e., solvent). The adhesive is light cured, after which incremental filling begins, followed by carving to form anatomy. After proper anatomy is achieved and occlusion is checked, the tooth is etched again and glazed. A surface glaze (BisCover LV, BISCO) is then placed on the restoration to lessen micro-leakage and post-operative sensitivity. This incremental-oblique filling technique works well for Class II indications. Different from incremental-horizontal filling, the use of metallic bands with oblique increments lessens the polymerization shrinkage of composites and reduces the chance of microleakage.

In a clinical example of this type of indication and technique, the old filling and decay are removed first. A sectional matrix is then utilized, along with a wedge and oblique filling. Nanofilled composite material (Venus Diamond, Heraeus) is applied to the restoration, with an enamel layer over it.

Fig. 1: Rubber dam isolation of broken-down teeth and restorations on teeth #30 and #31.

Fig. 2: Incremental filling was achieved by developing dentin cuspal inclines on teeth #30 and #31.

Note the sectional matrix and wedge are used to assure proper interproximal contours.

Fig. 3: View of the completed, integrated restorations with appropriate marginal ridge contact and contours.

Class IV

Class IV indications typically require diastema closure or full veneers and can involve no preparation to a full 1+mm of reduction.To help with a seamless restoration, a starburst bevel of 2+mm should be utilized, except on the gingival margin if dentin is exposed.Layering should be completed with at least two shades of a microhybrid material, overlaid with incisal/translucency, or microfill, to create the dentinal lobes, incisal translucency and the incisal halo. However, today we can achieve this with a nanohybrid composite (Venus Diamond).

Undetectable Margins

When margins are in the aesthetic zone, a starburst bevel should be used, followed by etching beyond the bevel.The outer layer of composite should be rolled, while wearing clean gloves, to improve sculptability and prevent voids. The material should then be placed and super-cured, allowing five minutes or more for the material to settle. The margin should then be addressed first, finishing it back between where the etch and the bevel end. Rubber wheels and polishers should not be used on the margins, since the rubber tends to become embedded in this area.

Management of Class II Division 1 Malocclusion PPT and Videos

        Problems in Class II Division I malocclusion

        Patients concerns

• Convex facial profile
• Prominent upper incisors

       Occlusal problems

• Increased over bite
• increased over jet

Class II Division I Malocclusion

Management of class ii division 1 malocclusion

View more presentations from Sumudu Medawela.



Watch these Videos of High Pull head gear and Twin Block Applience 

Development of Occlusion-Orthodontic Lecture note (PPT)

Prerequisite Knowledge

• Growth & development of face and jaws both prenatal and postnatal
• Eruption of teeth timing and sequence
• Morphology of teeth both primary and permanent
• Terminology of key words
• Masticatory movements and path of closure of the mandible

Development of Occlusion-Orthodontic Lecture Note

View more presentations from Sumudu Medawela.

Fissure sealing-Restorative Dentistry Lecture note

Indications

Sealing of susceptible pits and fissures is carried out as soon after eruption as possible. First, second, and third permanent molars are obvious candidates, but all molars are not automatically fissure sealed. Where plaque control is good (and this should be checked with disclosing solution) and where no lesion is visible, a sealant is not needed. However, caries or missing teeth which have been extracted because of caries in a child’s mouth indicate caries risk and will favour the use of sealants. Similarly, if a young adult requires restoration of one second molar, fissure sealing the remaining second molars seems to be a logical preventive measure. Fissure morphology is also relevant. A fissure pattern of shallow rounded grooves is unlikely to decay, but a deep fissure pattern is more susceptible since it is difficult to clean. Where the dentist believes that the patient’s diet contains frequent sugar intakes or when poor oral hygiene cannot be improved – for example where patients are mentally or physically disabled – fissures should be sealed. Children with significant medical conditions which put them at risk from the consequences of dental disease should also be offered sealant treatment. These medical conditions include cardiac problems, immunosuppression, bleeding disorders, blood dyscrasias, and metabolic and endocrine problems. Finally, the tooth to be fissure sealed must be capable of being isolated from salivary contamination since contamination while placing the sealant is the most common cause of failure. At best, salivary contamination will result in the sealant falling off, with no permanent harm. At worst, however, the sealant will be partly retained but leak, so that caries can progress beneath it, safe from salivary protection, fluoride ions, and detection by the dentist. Therefore good isolation from saliva is an essential part of the clinical technique, with a rubber dam being the preferred method.

Clinical technique for resin sealers

Anaesthesia and isolation

If necessary, a little local anaesthetic is infiltrated or topical anaesthetic is applied to avoid discomfort from the rubber dam clamp.

Cleaning

The tooth surface to be etched and sealed may be cleaned with a bristle brush in a handpiece and a pumice and water slurry. Oil-based polishing pastes or those containing fluoride should not be used, as these may interfere with etching. The pumice is washed away using the three-in-one syringe. Some dentists clean the fissure with a high-pressure spray of sodium hydrogen carbonate; this is known as ‘air polishing’. This is similar to ‘air abrasion’ as already described in earlier posts. In this format a high-velocity air stream contains soft sodium bicarbonate powder (baking soda), shrouded by water, and has little cutting effect on intact enamel. The powder is water-soluble and is easily removed after cleaning.

Etching

The tooth is now etched with phosphoric acid (30–50 per cent). The acid etchant is supplied by the manufacturer in the form of a coloured gel. The etchant is applied over the whole occlusal surface extending onto the lingual or buccal surface where grooves require sealing. Etching the entire occlusal surface avoids the danger of covering an unetched surface with sealant and thus inviting leakage. The acid can be applied with a brush, or alternatively the gel can be placed accurately with a disposable syringe and blunt needle. As soon as the complete area to be etched is covered with acid, the time is noted and the enamel is etched for 15–20 seconds.

(a) A brush is used to apply the etchant gel over the occlusal surface of the tooth to be fissure sealed. (b) Dried etched enamel appears matt, white, and frosty. (c) The sealant is applied to the etched surface using a small disposable brush or a syringe with a disposable tip. (d) Light-curing a fissure sealant. (e) A fluoride-containing varnish is applied to the etched enamel at the periphery of the restoration where it has not been covered with sealant.

a

b

c

d

e

Washing

After 20 seconds the acid is washed away. Initially a water jet from the three-in-one syringe is used to remove most of the acid. If a rubber dam is not in place, careful aspiration is important to avoid damage to soft tissue by the acid. After approximately 5 seconds of water, the air button is also pressed, forming a strong water–air spray which should be played over the etched surface for 20–30 seconds. With coloured gels, it is tempting to stop washing when the colour has gone. However, the purpose is not just to remove the surplus acid, but to flush the precipitates out of the newly formed etch pits, and this takes a full 20–30 seconds.

Drying

Many fissure sealants are still based on hydrophobic resins and so a careful drying regime is required. It is good practice to check that the airline is not contaminated by water or oil by blowing it at a clean glass or paper surface. The tooth surface is now thoroughly dried with air from the three-in-one syringe. This drying is most important since any moisture on the etched surface will stop penetration of the hydrophobic resin into the enamel. A minimum of 15 seconds drying is recommended. At this stage the etched area should appear matt, white, and frosty. With a rubber dam, there should be no danger of salivary contamination of the etched surface. If this does occur, however, it is essential to re-etch the enamel because adherent organic material in saliva will block the pores and it cannot be removed completely, even by vigorous washing.

Applying the sealant

Fissure sealants are supplied both as light-curing and chemically-curing materials. A light-cured resin does not require mixing but a chemically-cured resin has two components which are gently mixed together with a brush.

A sealant is applied to the etched surface using a small disposable brush or applicator supplied by the manufacturer.

The sealant is applied to the etched pits and fissures and up the etched cuspal slopes. If a light-cured material has been chosen, the light should be placed directly over the sealant but should not touch it. With a molar tooth, if the light source is of a smaller diameter than the tooth it should be directed at the distal part of the occlusal surface for the full curing time recommended by the manufacturer of the resin and then moved mesially for a similar period. Any buccal or palatal groove or pit should be similarly cured with the light source directly over it. Since the polymerizing lights are potentially damaging to the operator’s eyes, special eye-protective glasses should be used or the dental nurse should hold a special filter screen in the operator’s line of vision. Some lights Fissure sealing 123 have protective cups which can be placed over the end of the light guide. Most chemically-cured sealants polymerize in 1–3 minutes and the manufacturer’s instructions should be followed. The outer surface layer of any sealant will not polymerize due to the inhibiting effect of oxygen in the atmosphere. The sealant will therefore always appear to have a greasy film after polymerization. Finally, a fluoride-containing varnish may be applied to the etched enamel at the periphery of the restoration where it has not been covered with sealant.

Checking the occlusion

The rubber dam is now removed and the occlusion checked with articulating paper. Whilst it is considered acceptable to allow any high spots to be abraded away when unfilled resin fissure sealants are used, with the lightly-filled materials it is wiser to reduce high spots by grinding with a small round diamond stone in a low-speed handpiece.

Clinical technique for glass ionomer cement sealers

The authors would rarely choose a glass ionomer cement for fissure sealing because the scientific evidence on retention and caries prevention has shown these not to be as effective as resin sealants. It is possible that the fluoride in the material may exert a cariostatic effect. However, they are the material of choice on an erupting tooth, where oral hygiene is poor, caries risk is high, and good moisture control is difficult. They should be considered a temporary measure in these circumstances. The tooth to be sealed is isolated and the fissure is cleaned with 10 per cent polyacrylic acid-conditioning agent, supplied by the manufacturer, for 20 seconds. It is then washed and dried, and the glass ionomer material, mixed to a flowable consistency, is applied along the fissure and firmly burnished into position. Excess material is easily removed with the burnisher. Although glass ionomer will almost certainly be less well retained than a resin-based system, the material may have a protective effect for high-risk fissures whilst the tooth is at its most vulnerable: in this situation a resin sealant would not work because the tooth may be impossible to isolate satisfactorily.

A glass ionomer fissure sealant which has been in place for 14 years.

The sealant restoration (or preventive resin restoration)

Indications

The sealant restoration was born out of the use of pit and fissure sealants. It is a natural extension of the technique where pit and fissure decay is confined to one area in the fissure system. The technique restores the carious area and seals the rest of the fissures. The restoration is indicated where a cavity is present (either a microcavity in the enamel, or a cavity with dentine at its base). The lesion will usually be visible on a bitewing radiograph as an area of radiolucency in the dentine.

Clinical technique

(a) a lower second molar isolated with a rubber dam prior to placing a sealant restoration.

(b) Enamel is removed to gain access to obvious caries.

(c) Soft caries over the pulp is removed.

(d) Exposed dentine is covered with a calcium hydroxide-containing cement: smaller amounts of this type of cement would be used nowadays – simply covering the deepest dentine, close to the pulp.

(e) A second layer of glass ionomer lining may be placed in a deep cavity.

(f) The enamel walls of the cavity and the occlusal surface of the tooth are etched with acid.

(g) Etched enamel after washing and drying.

(h) Bonding resin is applied to the cavity walls and occlusal surface.

(i) The cavity is filled with composite resin. Use of the glass ionomer lining in this tooth allowed the composite to be placed and cured in a single 2 mm

increment.

(j) A fissure sealant is applied to the whole occlusal surface.

(k) The occlusion is checked with articulating paper which will locate areas of occlusal contact with a coloured mark.

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Cavity preparation

Occlusal contacts should be marked with articulating paper prior to preparation so that the dentist can remember where these contacts are. A local anaesthetic is given. A rubber dam is applied and the tooth is thoroughly cleaned as before (Fig. 7.3a). A small, pear-shaped tungsten carbide bur (Jet 330) is used in the air turbine to widen slightly and deepen the fissure and to gain access to caries in dentine. The air turbine is also used to remove the minimum amount of enamel necessary to gain access to caries. A small round bur is now used in the low-speed handpiece to remove soft, demineralized dentine, which is often stained, from the enamel–dentine junction. During this process the access cavity may require further enlargement to allow access to caries on the enamel-dentine junction. Thus high- and low-speed handpieces are used alternately so that the cavity is kept as small as possible commensurate with removing the soft dentine from the enamel–dentine junction so that it feels hard when a sharp probe is run along it. Finally, any soft caries overlying the pulp is removed with either a slowly rotating round bur in the slow-speed handpiece or a sharp excavator.

Lining and etching

If the cavity is much larger than expected, the deep dentine directly overlying the pulp may be covered with a calcium hydroxide-containing cement. A second layer of resin-modified glass ionomer may be placed in a deep cavity to act as a dentine replacement. The polyacrylic acid conditioning liquid supplied by the manufacturer should be applied to any exposed dentine with a brush. After 10 seconds the cavity is washed and dried and the glass ionomer cement placed. Once this material has set, any glass ionomer material on the enamel walls should be removed with a bur. The enamel walls of the cavity and the occlusal surface of the tooth are now etched with acid. After 20 seconds this is washed and dried as before.

Filling the cavity

A composite, designed for use in posterior teeth, is selected. It is supplied with a bonding resin which should be painted on the etched enamel walls and occlusal surface and blown with dry air to form a thin layer, avoiding puddles of material in the cavity. The resin is polymerized with light as before. The cavity is now filled with the posterior composite. These light-cured materials will not cure reliably in depths exceeding 2 mm. Thus, if the cavity is deeper than this (a graduated pocket-measuring probe can be used to check depth), the material must be placed in increments. Each increment is then cured before the next is placed, taking care not to dispense more than is needed because normal light in the surgery will polymerize the unused material. An increment of composite is placed or syringed directly into the cavity and gently nudged into position using a small ‘non-stick’ instrument. Care should be taken not to trap air under the material. When the final increment is placed an instrument is used to shape the occlusal surface, restoring cuspal inclines in the larger cavity before light-curing the material. Alternatively, the glass ionomer material is brought up to the enamel–dentine junction to replace all the missing dentine so that only one increment of composite, the thickness of the enamel, is required. An alternative to the glass ionomer/composite layered technique is to bond the composite filling materials directly to the etched dentine and enamel. This is called the all-etch technique. The enamel and dentine of the cavity and the enamel of the occlusal surface are etched for 15 seconds and then washed and gently dried. The dentine in particular should not be over-dried. Now a dentine bonding agent is applied following the exact descriptions of the manufacturer. The bonding agent is polymerized and then the composite is built up in increments as described previously.

Whether the layered technique or the all-etch technique have been used, the remaining fissure system has already been covered by the bonding resin. A layer of fissure sealant is now painted over the entire occlusal surface and polymerized. Alternatively, composite can be gently agitated with a plastic instrument into the adjacent pits and fissures, and light-cured to act as a heavily-filled pit and fissure sealant.

Finishing the restoration

Excess resin is carefully removed with 12-bladed tungsten carbide finishing burs or with fine diamond composite finishing burs. Once the rubber dam has been removed, the occlusal contacts should be checked with thin articulating paper. This is placed between the dried teeth and the patient is asked to move the teeth over each other as if eating. Any ‘high’ spot on the restoration will be located by a mark and can be reduced; the aim is to have the restoration in harmonious occlusion. The restoration can finally be smoothed with aluminium-impregnated rubber points.

Larger posterior composites

It is not uncommon for occlusal caries to undermine the occlusal enamel widely. In the past such restorations have often been restored with amalgam after all the overhanging enamel has been cut away. With posterior composite materials and glass ionomer cements, it is now possible to use these adhesive materials to restore the missing tooth tissue and support the remaining enamel without needing to remove so much of it. Therefore once soft demineralized dentine has been removed, decisions have to be made about the strength of the remaining tooth tissue. Figure c shows a large occlusal cavity with a considerable amount of overhanging enamel. This cavity was restored with a calcium hydroxide lining over the deepest pulpal part of the cavity used as an indirect pulp cap followed by a layer of glass ionomer cement to replace much of the missing dentine. Finally, the enamel walls were acid-etched and the remainder of the tooth restored with a posterior composite which was built up in increments as described previously. The same restoration is shown after 5, 9, and 14 years in Figs. In these large restorations as much sound tissue should be preserved as possible. Undermined and overhanging enamel can be supported with adhesive posterior composite materials and glass ionomer cements. Where mastication pressure is obvious, a minimum thickness of 2 mm of composite material is required. Where the outline of the preparation is placed beyond the occlusal surface, perhaps because a cusp has fractured or been completely undermined by extensive caries, a bevel should be prepared to optimize the adaptation of the composite to the enamel.

(a) A large occlusal cavity is present in the lower first molar.

(b) Access to caries begins to reveal the extent of the lesion.

(c) The enamel–dentine junction is made caries-free, soft caries is excavated over the pulp, and a calcium hydroxide-containing cement is placed in the depth of the cavity.

d) Much of the missing dentine is replaced by a second lining of glass ionomer cement. Today this would be brought up to the enamel–dentine junction and only one increment of composite would be required.

(e) An increment of composite being lightcured.

(f) The final increment of composite can now be placed.

(g) The completed restoration.

(h) The restoration after five years.

(i) The restoration after nine years. There is some wear, but the margins are intact and the restoration can still be considered a success. If this wear was thought to be excessive, the surface layer of composite could be removed and the restoration resurfaced with more composite. Such repairs, or maintenance procedures, are not possible with amalgam.

Modern composites are likely to be more durable than the materials available when the restoration was placed.

(j) The restoration after 14 years. Additional composite was not added as suggested in (i) and there has been no significant change in the last five years. The restoration can now be

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Congenital defects of Face PowerPoint Presentation

Includes

Cleft lip and palate

Developmental abnormalities of the jaw and teeth Cleft lip, alveolus,hard and soft palate are the most common congenital abnormalities of theorofacial structures.

• Cleft lip and palate is 1 in 600 live births.
• Isolated cleft palate is 1 in 1000 live births.

The typical distribution of cleft types is:

• Cleft lip alone 15%
• Cleft lip and palate 45%
• Isolated cleft palate 40%

Cleft lip palate predominates in male Cleft lip alone more in females. In unilateral cleft lip, the deformity affects left side in 60% of cases.

 

Congenital defects of the Face