SDEO complete denture design

Question 1

Maxilla feature on the skull?

Answer 1

The palate comprises a right and a left plate with the midline palatal suture; the sphenopalatine bones; the lateral slopes of the palate; the hamular notch; the pterygoid plates where the muscles of mastication are attached.

The posterior extension of the maxilla where the soft palate will ‘hang off’.

The alveolar bone and attachment of the muscles of mastication; the zygomatic buttress which is important with respect to denture support. The coronoid process of the mandible, demonstrating opening and translation of the condyle, proximity of the coronoid process to the buccal surface of the molar teeth influencing the space available for the buccal flange of the impression tray and later the buccal flange of the denture.

Question 2

Mandibular features on skull?

Answer 2

The external oblique ridge and the buccal shelf area.

The mylohyoid ridge (or line) where the mylohyoid muscle attaches.

The lingual flange extensions are determined by the functional muscles and the floor of the mouth.

The labial alveolar ridge and the mentalis muscle attachment.

Question 3

Maxillary features on silicone models?

Answer 3

The alveolar ridge crest; the incisal papilla; the labial frenum; the labial alveolar slope, height and thickness; the vestibular sulcus; the hamular notch; the vibrating line from one hamular notch to the other via the fovea palatinae which will lie behind the distal extension of the denture.

The vestibule depth and breadth are demonstrated anteriorly and posteriorly.

Question 4

maxillary features on stone cast?

Answer 4

The impression has captured the hard tissue features: the hamular notches; the depth of the sulci; the palatal midline suture. Also the soft tissue features of the masticatory mucosa - if this is excessively compressible ideally an impression of these tissues should be taken in the resting state – a ‘mucostatic’ impression.

The vault of the palate, the palatal suture, the rugae, the incisal papilla, the tuberosity area and the ridge height posteriorly and anteriorly are demonstrated.

Question 5

maxillary features on impression?

Answer 5

The impression has captured the functional depth of the sulcus, it extends just anterior to the vibrating line. Thick, well rounded impression borders depict the functional depth of the sulci, the height of the palatal vault and the tuberosity areas are also depicted.

Question 6

Mandibular features on silicone models?

Answer 6

The tongue space must be respected and used to manipulate the impression material to the tongue.

The height of the residual ridge; the sulcus depth and width are demonstrated; The buccal shelf and retromolar pads must be captured to determine the extent of the denture.

Clinically assess the retromylohyoid space available for the potential distolingual denture flange by palpating the mylohyoid ridge whilst noting its sharpness.

Question 7

Mandibular features on stone cast?

Answer 7

Distolingual depth and width is adequately depicted as is the buccal shelf and also the retromolar pads.

The lingual flange of the resultant denture will at an angle so as to engage the sublingual tissues and provide a peripheral seal.

Question 8

Mandibular features on impression?

Answer 8

Impressions should have rounded borders, depth and width; the distolingual area of the impression should be ‘s’ shaped. A denture constructed on casts from such an impression should fit well in the mouth with adequate relief for all frenal attachments.

Question 9

maxillary and mandibular features on acrylic dentures?

Answer 9

he horizontal distance between the index finger on the incisive papilla and the probe against the incisal edge of the labial surface of the maxillary central incisors should be 1cm, one of several biometric guides.

The width of the denture base reflects the resorbed residual ridge in the mouth.

The buccal shelf area; extension to the retromolar pad and the depression of this ‘pear shaped pad’ is seen on the denture base.

The distolingual flange shown. The height of the labial flange acrylic depicts the amount of tissue replaced by the denture.

Question 10

definition of support?

Answer 10

the resistance of vertical movement of a denture towards the ridge

Question 11

Which are support areas for the maxillary complete denture?

Answer 11

Alveolar mucosa
Hard palate
Zygomatic buttress
Ridge Crest

Question 12

Which are support areas for the mandibular complete denture?

Answer 12

Alveolar mucosa
Buccal shelf
Pear shaped pads

Question 13

To assist in the construction of /F with a good peripheral seal the master impressions should?

Answer 13

Have well rounded borders

Be adapted to the sublingual tissues

Be sigmoid in shape in the lingual flange area

Question 14

Biometric guides may assist with?

Answer 14

Tooth position
Aesthetics
Assessing the Freeway Space

Question 15

maxillary primary impression?

Answer 15

(Edentulous stock trays) Rotate into the mouth, placing heels first and looking through to check engagement of the hamular notch by the tray and that the tray covers the labial aspect of the alveolar ridge sufficiently.

Tray handle is useful to manipulate, place and stabilise the impression tray.

Question 16

3 green dots?

Answer 16

The tray should have tissue stops 3 mm in height to allow space for the alginate

these are in a tripod position; 2 on the posterior ridge / tuberosity areas and 1 in the midline / rugae area. These may be placed in softened greenstick compound or 2 small balls of silicone putty mixed and placed.

Question 17

what is applied after tissue stops?

Answer 17

adhesive

Adhesive must be applied to facilitate retention of the alginate to the tray; take care to also apply the adhesive 2-3 mm beyond the edge of the tray on the external surface.

Question 18

Place alginate where before taking imp?

Answer 18

The distobuccal sulcus is the deepest area in the maxilla and the area most likely to trap air bubbles; alginate taken on the index finger and applied here can prevent this.

applied to the midline of the palate to reduce air entrapment

Question 19

taking maxillary primary imp?

Answer 19

Alginate should also be applied to the midline of the palate to reduce air entrapment. Note - warmth of the oral cavity will hasten setting of the alginate therefore the tray must be ready to be placed as soon as alginate has been applied to the mouth. The loaded tray is rotated into the mouth, heels placed first and moved into position allowing the impression material to flow anteriorly into the buccal and labial sulci. Manipulate tissues allowing air to escape and moulding the impression material, pulling the cheek and labial tissues upwards, downwards, and right and left - and in the case of the buccal tissues, buccally and posteriorly - moulding the impression material to the depth of the functional sulci.

Question 20

Maxillary Acrylic Special Tray Features

Answer 20

The tray has a handle which is ‘stepped’ to allow space for the lip. The tray should have adequate thickness - 3mm - and be constructed of a material of sufficient rigidity

Question 21

maxillary secondary imps?

Answer 21

Check tray heels are placed first.

There is a 2mm space between the mucobuccal fold and tray - it is not overextended peripherally - and there is frenal relief.

Tissue stops are being placed on the ridge crests in greenstick (to stabilise the tray, prevent tissue compression as well as providing space for impression material).

Border trimming section by section, cooling the greenstick in warm water to ensure patient does not get burnt but keeping the greenstick ‘mouldable’.

A finger may be used to push greenstick into the depth of the sulcus - and tissues used to mould it - obtaining rounded edges/margins.

Applied along the periphery of the tray, from the buccal frenum to the labial frenum, continuing in sections

Further increments are added, tempered in hot water, again pressed into the depth of the sulcus with up and down, left and right manipulation of the tissues to mould the material.

To help create the posterior palatal seal, ask the patient to blow through their nose while their nostrils are pinched closed; increasing the intranasal pressure to allow the soft palate to mould the greenstick.

A blow torch may be used to soften the greenstick compound uniformly without blistering the material, tempering it in hot water before refining the border moulding.

NB care to be taken when using gloves with a naked flame - it is safer to use a ‘Safe-air’ device.

Subsequently adhesive is applied evenly, the tray is filled with silicone (not overfilled), the tray stabilised in the mouth, and tissues manipulated again to facilitate recording of the functional depth.

Checking the functional depth has been recorded.

Question 22

The Maxillary Flabby Ridge case

Answer 22

In this case the flabby ridge is in the anterior section. A ‘window’ technique is used to record the secondary impression to construct the maxillary complete denture. Tray material in this area is trimmed away so it does not cover the area between the canines.

Other features of this tray - it is 2mm away from the functional depth so it can be border moulded appropriately. The window of the tray must have a lid constructed to cover. The handle is best constructed as a rim on tip of the ridge rather than in this position where it may get in the way causing discomfort to the patient. Demonstrated is the window exposing the flabby ridge.

Adhesive is applied along the periphery and putty impression material used to border mould buccally and labially, then to the posterior extent of the tray separately.

If border moulding material debonds from the tray do not allow this to compromise the final impression rather remove and redo the border moulding, taking care while using the scalpel to avoid injury.

Apply adhesive and load, but do not overload the tray, applying material to all areas except over the window area. Any material flowing into this window space may be trimmed away using a scalpel, again taking care to avoid injury.

Adhesive is applied to the lid and lid placement is practised ensuring excess impression material is removed from the periphery of the window to allow the lid to seat. The lid should be constructed to overlap the tray window margins by 2mm - this will prevent compression of the flabby ridge - and obtain a mucostatic impression.

The rounded tray edges depict the full width of the sulcus.

Question 23

The Mandibular Primary Impression

Answer 23

Tray selection is carried out as before.

Silicone is applied as a sausage and moulded to anatomy: the material may be pinched to the distolingual flange area. The tray is inserted and a finger may be used distolingually to push the putty into the distolingual sulcus: an ‘s’ shape should be observed.

The impression is disinfected and extensions of the special tray marked with a marker 2mm short of the periphereal reflections and extending fully over the retromolar pad.

Question 24

The Mandibular Secondary Impression with Silicone

Answer 24

Silicone putty may be used for border moulding - here demonstrated on the mandibular tray - however this must be ‘right first time’ unlike greenstick which, as previously demonstrated may be softened and refined. Silicone border moulding would be completed in sections similar to using greenstick OR applied buccally then lingually however consider the working time of the material and the factors influencing the setting time - eg. the base and catalyst ratios and the room temperature. Mixing time should not extend into the setting time.

The patient should be asked to move their tongue forward to touch their upper lip, the midline of the palate and then to move their tongue to the right and left along their upper lip.

Silicone stops may be added at this time.

The tray is loaded (not overloaded but the periphery must be covered), again it is rotated into the mouth, firstly seated posteriorly over the retromolar pads, then seated anteriorly to allow material to flow forwards; tissue moulded and tray stabilised. The tray handle is shown to allow space for the lower lip to be manipulated.

In one sharp movement the tray is removed.

Question 25

The Maxillary Flabby Ridge case

Answer 25

In this case the flabby ridge is in the anterior section. A ‘window’ technique is used to record the secondary impression to construct the maxillary complete denture. Tray material in this area is trimmed away so it does not cover the area between the canines.

Other features of this tray - it is 2mm away from the functional depth so it can be border moulded appropriately. The window of the tray must have a lid constructed to cover. The handle is best constructed as a rim on tip of the ridge rather than in this position where it may get in the way causing discomfort to the patient. Demonstrated is the window exposing the flabby ridge.

Adhesive is applied along the periphery and putty impression material used to border mould buccally and labially, then to the posterior extent of the tray separately.

If border moulding material debonds from the tray do not allow this to compromise the final impression rather remove and redo the border moulding, taking care while using the scalpel to avoid injury.

Apply adhesive and load, but do not overload the tray, applying material to all areas except over the window area. Any material flowing into this window space may be trimmed away using a scalpel, again taking care to avoid injury.

Adhesive is applied to the lid and lid placement is practised ensuring excess impression material is removed from the periphery of the window to allow the lid to seat. The lid should be constructed to overlap the tray window margins by 2mm - this will prevent compression of the flabby ridge - and obtain a mucostatic impression.

The rounded tray edges depict the full width of the sulcus.

Question 26

muscostatic impression?

Answer 26

the impression is taken with the mucosa in its normal resting position.

Question 27

How to take mucostatic imp?

Answer 27

A special tray is constructed with a window over the flabby ridge and with the peripheral extension up to 3mm short of the functional sulcus depth.

Beads of putty are applied to the fitting surface of the special tray, these are placed over the tissue stops which were prescribed in acrylic, these ‘stops’ will stabilise the tray; prevent compressing the tissues and will also ensure space for the impression material.

The tray is placed in the mouth for adaptation of the putty, note the window over the flabby tissue.

In the distobuccal sulcus area on the left side putty is used to border mould the tray, a finger being used to mould the material into the sulcus depth and hamular notch area, then the cheek tissues are manipulated up, out, down, forwards and backwards in a rotating motion 2 to 3 times to obtain the correct functional depth and position of frenal attachments before the putty sets.

The tray is removed to inspect the quality of the border moulding to ensure the border moulded area is thick, rounded and smooth which gives not only the sulcus depth but the width of the sulcus which will be filled by the flange of the denture.

Clinical examination will ensure the border moulding has captured the full functional depth in this area.

The Right disto-buccal sulcus, the hamular notch and buccal areas are similarly border moulded - again an index finger and manipulation of the cheeks moulding the putty to the functional sulcus.

It is important the chosen material has adequate working time to allow border moulding to be completed. If the material is set before completion you must remove it and apply a new mix having ensured there is adequate (but not excessive) adhesive on the tray.

Ensure the mandible is moved to the Right and to the Left so the coronoid processes can mould the border moulding material to the thickness of the functional sulcus.

Subsequently the anterior sulcus may be border moulded following the application of another section of putty.

Then the postdam area. Once the border moulding is completed the material should be free of wrinkles or folds.

Medium body silicone material (or an alternative) should be loaded into the tray and the impression taken and border moulded. This material should not cover the window area.

The tray is subsequently removed and any flash in the window area is trimmed and the tray replaced in the mouth.

Light body material should be applied onto the flabby tissue through the window and the lid placed over the window.

The lid peripheries will overlap the special tray bordering the flabby tissue; the lid will have its own handle and be supported by this - ensuring no pressure is applied to the underlying flabby tissue.

Question 28

Stops placed on a special tray will?

Answer 28

Stabilise the tray Prevent compressing the tissues
Ensure space for the impression material

Question 29

In the technique demonstrated the customised special tray used to take a mucostatic impression was?

Answer 29

Constructed with a window over the flabby ridge

Used with polyvinyl siloxane material of different viscosities