GB2457044A

GB2457044A - Tough and resilient denture spacer

Info

Publication number: GB2457044A
Application number: GB0801693A
Authority: GB
Inventors: Grenville Nicholas Flint
Original assignee: SEALDOWN MEDICAL Ltd
Current assignee: SEALDOWN MEDICAL Ltd
Priority date: 2008-01-31
Filing date: 2008-01-31
Publication date: 2009-08-05
Also published as: GB0801693D0

Abstract

A spacer for use in retaining a space between a mould surface (11a, 11b) and a base material (20) during construction of a soft lining (21) of a denture (6), the spacer comprising a spacer material (14), wherein the spacer material (14) is resilient and displays a high toughness value. Also provided are a process for making a denture (6) having a soft lining (21), a denture (6) made using the spacer and a custom-made denture made according to the process. The spacer material (14) may further have toughness greater than 0.94 J/m3, comprise silicon, have a setting time less than 15 minutes and a be 0.5mm to 4mm thick. It may also be formed from a two part mix comprising a base component and a catalyst component.

Description

DENTURE SPACER AND METHOD FOR MAKING A DENTURE

USING THE SANE

The invention relates to a denture spacer and a method of making a soft lining denture using a denture spacer.

Known standard dentures typically comprise a rigid base, usually acrylic, with a pre-fabricated tooth part set therein. The rigid base can be custom made to fit a patient's oral tissues comfortably. Typically, this type of denture is secured in the mouth using a fixative, which provides a thin sticky film between the two closely fitting surfaces (the tissues and the rigid base) . This sticky film prevents air from getting between the surfaces and the denture is retained in the mouth through suction.

Standard dentures are made using a two-part mould casing; a first part developed from an impression of oral tissues, which mimics the oral tissues of a patient's mouth; and a second part made using a "temporary denture" or "mock-up" of the denture as a pattern.

It is known to provide a denture with a soft lining. By nature, a soft lining is flexible and soft, so that a comfortable fit of the denture in a patient's mouth can be achieved. Their flexibility facilitates a close fit with the oral tissues, which helps to retain the denture in the mouth.

Soft lining dentures can be made with the aid of a spacer.

A spacer aids construction of the rigid base of a denture by retaining a "space" between a pre-cursor base material (which eventually forms the rigid base) and a first part of the two-part mould casing (which mimics the inside of a patient's mouth) Known spacers require a substantial "setting time" of around 30 minutes or more before they can perform their space retaining function.

During formation of a denture, a base material is applied over the top of the "set" spacer, a tooth part is positioned in the base material and the second part of the mould casing is placed over the arrangement to facilitate the shaping of the base material into a partly formed denture with the tooth part in an initial processing stage, by applying a compression force. After this initial processing stage, the spacer is removed and replaced by a soft-lining material. The soft lining and the partly formed denture are subjected to an additional processing stage, by applying heat and compression to form the soft-lining denture, i.e. by hardening the base, setting the soft-lining, creating a bond between the soft lining and the base and setting the tooth part firmly in place.

Known spacers are brittle and hard and are susceptible to cracking or snapping during the initial processing stages, which may damage the rigid base and may result in a denture with an uncomfortable or unsuitable fit. The process of making a soft lining denture can therefore be frustrating and time consuming, because the process is unpredictable when used with known spacers.

Therefore, an aim of the invention is to provide a spacer and a method of using the same that minimises the problems with known spacers.

A further aim of the invention is to provide a method of making a soft lining denture that is cost effective and time efficient to make.

According to a first aspect of the invention therefore, there is provided a spacer for use in retaining a space between a mould surface and a base material during construction of a soft lining of a denture, the spacer comprising a spacer material, wherein the spacer material is resilient and displays a high toughness value.

The invention extends to a denture made using the spacer.

Advantageously, the resilient consistency of the spacer of the present invention provides a firm, but flexible support for the base material during initial processing stages of denture construction.

Toughness is the combination of the parameters of high tensile strength, but also high elongation potential that allow the material to stretch. In other words, toughness should be understood as the resistance to fracture of a material when stressed. Toughness can be defined in units of energy per unit volume.

Advantages of the consistency of the spacer material include that the spacer shows: a resistance to cracking, snapping or tearing; and a mildly deformable nature under compression conditions.

The toughness of the material may be greater than 0.94 Joules/m, preferably, greater than 1.02 Joules/m' and more preferably, greater than 1.10 Joules/mt An optimum value may be 1.18 Joules/m.

Preferably, the spacer material comprises silicone.

Preferably, the spacer material is a polysiloxane material, more preferably a vinyl polysiloxane (VPS) material.

The spacer material may be selected from one or more of the following: AquasilT14 Ultra LV (commercially available from DENTSPLY DeTrey GmbH); PanasilTM contact two in one (commercially available from Kettenbach GmbH & Co. KG); ProvilTN novo light C.D.2 (commercially available from Heraeus Kulzer GrnbH); 3111TM ESPETM ExpressTM (commercially available from 3M ESPE). Most preferably, the spacer material used is 3MTM ESPETM ExpressTM.

Other materials, which are resilient and display a high toughness value, as discussed above, may also be used.

Preferably, the spacer material has a setting time of less than 15 minutes, more preferably less than 10 minutes, preferably still less than 5 minutes, most preferably less than 1 minute.

By "setting time", it is meant the time that has lapsed, after which the spacer material shows a change in viscosity, i.e. from a lower resistance of the material to flow under an applied force to a greater resistance, so that the resultant spacer does not substantially change in shape, when a moderate pressure is applied thereto.

Advantageously, in the absence of any requirement for a prolonged "setting time", i.e. in excess of fifteen minutes after application, the time involved in making custom-fitting mouth apparel is reduced.

The spacer material may be formed from a two-part mix. The two-part mix may comprise a base component and a catalyst component.

The advantages of a two-part mix include the freedom to prepare a spacer material which displays a desired viscosity to aid the application, i.e. which has a lower resistance to flow under an applied force prior to elapsing of the "setting time" of the spacer material.

Preferably, the spacer comprises a layer of the spacer material. The spacer may therefore vary in thickness across a length and width of the layer. Preferably, the thickness of the spacer varies between approximately 0.5mm and 4mm in thickness across the length and width of the layer. The spacer may comprise a thickness of approximately between 2mm -3mm in a central region thereof. The spacer may comprise a thickness of approximately between 0.5mm -1mm in edge regions thereof.

The spacer may further comprise one or more separating membranes on an upper and/or lower face of the spacer, which membranes may facilitate separation of the spacer from a surface. The, or each separating membrane preferably comprises a substantially chemically impermeable film.

According to a second aspect of the invention therefore, there is provided a process for making a denture having a soft lining, the denture comprising a tooth part attached to a rigid base and a soft lining attached to said rigid base, for contact with oral tissues, the method comprising the steps of: a) arranging a spacer on a dental impression surface; b) arranging a base material over said spacer; C) positioning the tooth part in said base material; d) applying a compression force to compress the base material, tooth part and spacer together to form a precursor denture; e) replacing said spacer of the precursor denture with a soft lining material; and f) processing the precursor denture and the soft lining material to form said soft lining denture; wherein the spacer comprises a spacer material, which spacer material is resilient and displays a high toughness value.

Advantageously, due to the properties of the spacer material used, the spacer is able to withstand the compression forces involved in the manufacture of the soft lining denture without being damaged or causing damage to the precursor denture during compression. This results in a more efficient and more reliable manufacturing process of a soft lining denture.

Preferably, the features of the spacer and the spacer material described in connection with the first aspect of the invention apply mutatis mutandis to the second aspect of the invention.

The dental impression surface preferably imitates a patient's oral tissues.

Typically, the dental impression surface is obtained by taking an impression of said patient's oral tissues, although this step of the process is not encompassed by the present invention. Preferably, a replicate model of the patient's oral tissues is made from the impression of said patient's oral tissues, which comprises the dental impression surface.

Preferably, a two-part mould casing is used in the process for making said soft lining denture. Most preferably, the two-part mould casing is made prior to step a) of the process.

The two-part mould casing preferably comprises first and second parts each having a contact face with a peripheral cooperating edge region. Preferably, when the two-part casing is assembled with full contact between the cooperating edge regions, a fixed volume dental mould cavity is established.

Preferably, the replicate model of the patient's oral tissues comprises a first part of the two-part mould casing.

Preferably, the method of forming a second part of the two-part mould casing comprises the steps of: I. arranging a "temporary denture" on the dental impression surface of the first part of the two-part mould casing; II. arranging a mould material around the "temporary denture"; III. applying a compression force to the mould material, the "temporary denture" and the first-part of the two-part mould casing to compress the mould material around the "temporary denture"; and IV. processing at least the mould material and the first-part of the two-part mould casing to form the two-part mould casing.

Preferably, the mould material comprises a suitable plaster material. Most preferably, plaster of Paris is used (CaSO4.0.5HO) Preferably, the "temporary denture" comprises the tooth part, which is at least partly embedded in a palette-shaped member. Preferably therefore, the palette-shaped member comprises a deformable or malleable modelling material.

Preferably, with subsequent removal of the palette-shaped member from the two-part mould casing, the dental mould cavity is established.

Preferably, the palette-shaped member is removable from said two-part mould casing prior to step a) Removal of the palette-shaped member may be by transformation of the material into a pourable liquid state. The liquid material may be poured away by partial separation of the two-part mould casing. Preferably therefore, the palette-shaped member comprises wax and transformation into a liquid pourable state is effected by applying heat to the wax whilst it is in the two-part mould casing.

Alternatively, the palette-shaped member may be removed by separation of the two-part mould casing and lifting out the palette- shaped member.

Preferably, the tooth part is retained by the second part of the two-part casing.

By forming the mould casing prior to the construction of the denture, the spacer does not need to be subjected to additional compression forces during the formation of the mould casing.

Preferably, the arrangement of the spacer on the dental impression surface in step a) comprises applying a layer of spacer material to the dental impression surface before the "setting time" has lapsed (defined previously).

Preferably, the layer of spacer material is manipulated on the dental impression surface before the "setting time" has lapsed, to create smooth tapering edges.

Preferably, the base material is arranged in a layer over said spacer in step b).

Preferably, the base material is arranged over said spacer, by introduction of the base material into the assembled two-part mould casing. Preferably, in this case, the base material is a low viscosity liquid in a first state, with a low resistance to flow and which is therefore capable of being injected into the two-part mould casing using a syringe.

Alternatively, the base material is arranged over said spacer, in the absence of the second part of the two-part mould casing. The base material may therefore be a semi-solid in a first state, in which it is capable of being moulded or modelled over the spacer, for example, as a putty.

Preferably, the base material comprises a polymerized synthetic or chemically modified material. Most preferably, the base material comprises a natural, synthetic or chemically modified resin.

Preferably, the base material comprises PMMA (polymethylmethacrylate) Preferably, in step c), the positioning of the tooth part is effected by the two-part mould casing.

Preferably therefore, in one aspect of the invention, the tooth part is suspended above the denture mould cavity by the second part of the two-part mould casing, the tooth part being partly surrounded by injected base material.

In an alternative aspect of the invention, the tooth part may be retained in the second part of the two-part mould casing and through subsequent assembly of the two-part mould casing around the base material the tooth part may be embedded in the semi-solid base material.

The tooth part may comprise plastics material, preferably acrylic.

Preferably, in step d), the applied compression force is effected by forcing the first and second part of the two-part mould casing together, to establish the fixed volume of the dental mould cavity around a volume of base material that exceeds the fixed volume of the dental mould cavity, thereby having a squeeze effect on the volume of base material therein. Preferably therefore, the cooperating peripheral edge regions are brought together, to establish full contact with one another.

By forcing the first and second part of the two-part mould casing together so that the peripheral edge regions contact one another, the fixed volume dental mould cavity is established and any excess base material is displaced from the cavity and squeezed out in the process, to result in a compact precursor denture.

Preferably, in step e) the soft lining material is arranged on the dental impression surface to replace the spacer. Preferably, the soft lining material is moulded to substantially the same shape as the discarded spacer, by compressing the soft lining material between the dental impression surface of the first part and the precursor denture in the second part of the two-part casing.

Preferably, the soft lining material comprises a dough.

The soft lining material preferably comprises silicone.

Preferably, the soft lining material can be processed to form a flexible, rubber-like lining. Preferably, the processing of the soft lining material comprises heat curing of the material. By "heat curing" it is meant that toughening or hardening of a polymer material by cross-linking of polymer chains effected through the application of heat is achieved.

Therefore, the soft lining material is preferably Molloplast B (commercially available from Buffalo Manufacturing Co., Inc.), although other materials with substantially the same properties may be used.

Preferably, the processing step f) comprises hardening of the compressed base material of the precursor denture to form the rigid base of the soft lining denture. The processing step f) may further comprise securing of the tooth part in said rigid layer.

Preferably, the processing step f) comprises processing of said soft lining material into the soft lining.

Preferably, the processing step f) comprises bonding the soft lining to the rigid base.

Preferably, the actions of the processing step f) described above are effected simultaneously in a single stage processing step. The processing step f) may therefore comprise the application of a compression force in combination with heating of the precursor denture and the soft lining.

The compression force is preferably applied by the two-part casing as described previously.

Preferably, the heating of the precursor denture is in accordance with the appropriate manufacturers instructions for each material, which comprises a part of the precursor denture.

Preferably, the heating of the precursor denture comprises the use of a heat source. Preferably, the temperature of the precursor denture is increased gradually to at least approximately 60°C, preferably at least approximately 100°C, over a time period of at least approximately 2 hours. By "increased gradually", it is meant that the temperature of the heat source is increased by a generally uniform amount per unit time to effect a generally uniform increase in temperature of the precursor denture.

Preferably, the processing step f) further comprises subsequently allowing the precursor denture to cool without the application of an auxiliary cooling source.

In other words, preferably, the air surrounding the two part casing gradually cools the precursor denture within the casing.

This gradual heating and cooling of the precursor denture facilitates polymerisation of at least the soft lining material and prevents damage to the denture materials usually caused by rapid temperature changes.

Alternatively, some or all of the actions may be applied in a series of stages, including the application of compression forces and/or heat to the precursor denture and the soft lining, according to the action to be performed at each stage. For example, the processing of the base material may comprise a hardening stage through the application of a compression force, which may be followed by a heat curing stage for the soft lining, followed by a soft lining-rigid base bonding stage through the application of a compression force and! or heat.

The soft lining denture is preferably custom-made for an individual patient.

According to a third aspect of the invention, there is provided a custom-made denture made according to the above method.

All of the features described herein may be combined with any of the above aspects and in any combination.

For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which: Figure 1 shows a cross-sectional side view of a maxillae; Figure 2a -2j show a cross-sectional side view of the steps involved in the manufacture of a soft lining denture according to the invention; Figure 3 shows a cross-sectional side view of a denture made according to figure 2; Figure 4 shows a cross-sectional front view of a soft-lining denture made according to the invention; Figure 5 shows a cross-sectional front view of a soft-lining molar denture made according to the invention; Figures 6a shows a plan view of a soft-lining upper mouth denture in use made according to the invention; Figure 6b shows a A-B cross-sectional front view of the denture of figure 6a; and Figure 6c shows a C-D cross-sectional front view of the denture of figure 6a.

As shown in figure 1, a patient's jaw comprises a maxilliary (jaw) bone 1 which is covered in soft tissue 2 and forms a palette 3 and a lip 4 (upper or lower). The maxilliary bone 1 forms a tooth foundation 5 from which naturally occurring teeth normally project (not shown), between the lip 4 and the palette 3.

As shown in figure 3, a custom-fitting soft lining denture 6 made according to the invention, comprises a false tooth or tooth part 7, attached to a rigid base 8, which is lined with a thin layer of a soft lining material 21.

A variety of arrangements for soft lining dentures can be seen in figures 4 -6, for example in figures 4 and 5. In figures 6a -6c, different cross-sectional views of a denture can be seen.

The manufacturing process for making a custom-fitting denture 6 with a soft lining 21 typically requires an initial impression 9 of oral tissues of a patient's mouth, taken by a dentist, using a deformable alginate material in an impression tray (figure 2a) From the initial impression 9, a replicate model 10, which mimics the oral tissues of a patients mouth is created (figure 2b) . The replicate model 10 is then transformed into a first part 11 of a two-part mould casing 13, which provides a dental impression surface comprising a palette portion lla and a tooth foundation portion llb (figure 2c), with a substantially flat, peripheral edge region llc.

A layer of wax 16 is moulded over the dental impression surface lla, llb (figure 2c) . One or more plastic (usually acrylic) teeth 7 are embedded in the wax 16 in the region of the tooth foundation portion llb (figure 2d) to form a temporary denture 18.

A mould material 19, such as a plaster of Paris or other similar material is packed around the temporary denture 18 and against the peripheral edge region llc of the first part 11. A compression force is applied to the mould material 19 to compress the mould material 19 and form a snug fit around the temporary denture 18 and against the peripheral edge region llc of the first part 11. The mould material 19 is left to harden. The resultant second part 12 of the two-part mould casing 13 comprises a moulded surface 12a, a tooth cavity 12b and a corresponding substantially flat peripheral edge region 12c (figure 2e) Heat of a suitable temperature to melt the wax layer 16 into a liquid pourable state, is applied to the two-part mould casing 13, following which, the two-part mould casing 13 is partially separated to facilitate pouring away of the wax layer 16. The tooth 7 remains in position in the tooth cavity 12b of the second part 12 of the two-part casing 13.

The two-part casing 13 can be separated and reassembled.

When the two-part casing 13 is fully assembled, the corresponding peripheral edge regions lic, l2c of the two parts 11, 12 are brought into contact with one another, as later shown in figure 2g, to define a dental mould cavity.

The tooth 7 is suspended in the tooth cavity l2b above the dental mould cavity when the two-part mould casing 13 is re-assembled at this stage.

The dental impression surface ha, lhb is coated in a layer of suitable spacer material 14 with a thickness of approximately between 1 mm and 2mm to produce a spacer 14 (figure 2f) . The material of the spacer 14 is advantageously resilient and displays a high toughness value, in accordance with the definition of toughness as described above. The toughness of the spacer material 14 used in this embodiment is approximately 1.18 Joules/m?.

The spacer material 14 is vinyl polysiloxane (VPS) and is offered under the name 3NT ExpressTM material. However, toughness values of greater than approximately 0.94 Joules/m? are acceptable for the application and therefore material such as the following could be used as alternatives: AquasilTM Ultra LV (t = approximately 0.94 Joules/m); Panasil contact two in one (t = approximately 1.02 Joules/inl; or Provil novo light C.D.2 (t = approximately 1.02 Joules/m3).

Following a "setting time" of approximately between 30 seconds and 15 minutes, the dental mould cavity is over-filled with a base material 20 and the second part 12 of the two-part mould casing 13 is forced together with the first part 11, thereby bringing the peripheral edge regions llc, 12c into contact and in the process, squeezing out any surplus base material 20.

A PMMA (polymethylmethacrylate) material is used as the base material, although other suitable materials could be used.

The result is a precursor denture 18 arranged over a resilient spacer 14, the precursor denture comprising a compact base material 20 (PNMA) with the tooth 7 firmly embedded therein (figure 2g).

The two-part mould casing 13 is separated and the spacer 14 is removed (figure 2h) having retained an appropriate space within the two-part mould casing 13, for replacement by a soft lining material 21.

A layer of soft lining material 21 is laid over the dental impression surface lla, llb (figure 2i) and the two-part mould casing 13 is reassembled (figure 2j). Any excess soft lining material 21 is squeezed outwardly between peripheral edge regions llc, 12c of the casing 13 during a compression step.

The soft lining material 21 used for the purpose of describing the invention is Molloplast B dough, a silicone-based dough that can be heated or cured to produce a permanently flexible, soft material, which is suitable for lining a rigid base 8 of the denture.

Therefore, the two-part mould casing 13 enclosing the soft lining material 21 and the precursor denture 18 is processed.

During processing, the soft lining material 21 and the precursor denture 18 are subjected to a heating stage within the two-part casing 13, until a) the base material hardens to form the rigid base 8 with the tooth 7 firmly set therein; the soft lining material layer 21 is cured; and a bond is formed between the soft lining later 21 and the rigid base 8 to create the resultant denture 6.

The compression force applied by the two-part casing is retained during the heating stage.

The heating stage comprises a gradual increase in temperature of an applied heat source, to effect a gradual, uniform increase in temperature of the precursor denture. The precursor denture is gradually heated to a temperature of approximately 100°C over a time period of approximately 2 hours. The precursor denture 18 is subsequently allowed to cool naturally in the absence of a cooling source.

The denture 6 can then be released from the two-part casing 13.

In the prior art, a hard spacer is used in place of the silicone spacer 14, which needs to be processed to effect "setting" before the wax can be applied. The processing of known hard spacers takes approximately 30 minutes and this step is performed before the application of the wax layer and subsequent compression steps to create the second part 12 of the casing 13.

Furthermore, during compression, known hard spacers often fracture due to an inflexible and brittle nature, which damages the rigid surface 8 in addition to the dental impression surface ha, lib. This often results in the manufacturing process having to be repeated and in the most severe of circumstances, the first part 11 of the two-part mould casing 13 has to be re-constructed as it is damaged and is therefore, no longer useable.

With the spacer and method of the present invention, the first compression step is avoided, but also, during the second compression step, due to its resilient consistency and toughness, the spacer 14 provides a firm, but flexible support against which the base material 20 can be compressed. The spacer 14 is able to withstand the compression forces without cracking or snapping which has a positive impact on the shape and quality of the resultant denture 6.

Furthermore, this type of spacer 14 allows the base material 20 to develop gentle contours, which reflect the contours of the oral tissues, which are eventually reflected in the rigid base 8.

Further still, the "setting tine" of the spacer 14 of the invention is significantly shorter than the "setting time" of known spacers.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the sane, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

For example, it would be possible to use other materials than those specifically described for the rigid base 8 and the soft lining 21 of the denture.

Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features

disclosed in this specification (including any

accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. 2)'

Claims

1. A spacer for use in retaining a space between a mould surface (ha, lib) and a base material (20) during construction of a soft lining (21) of a denture (6), the spacer comprising a spacer material (14), wherein the spacer material (14) is resilient and displays a high toughness value.

2. A spacer according to claim 1, wherein the toughness of the spacer material (14) is greater than 0.94 Joules/m.

3. A spacer according to any one of claims 1 to 2, wherein the spacer material (14) comprises silicone.

4. A spacer according to any one of claims 1 to 3, wherein the spacer material (14) has a setting time of less than 15 minutes.

5. A spacer according to any one of claims 1 to 4, wherein spacer material (14) is formed from a two-part mix comprising a base component and a catalyst component.

6. A spacer according to any one of claims 1 to 5, wherein the spacer comprises a layer of the spacer material (14)

7. A spacer according to claim 6, wherein the thickness of the spacer varies between approximately 0.5mm and 4mm in thickness across the length and width of the layer.

8. A process for making a denture (6) having a soft lining (21), the denture (6) comprising a tooth part (7) attached to a rigid base (8) and a soft lining (21) attached to said rigid base (8), for contact with oral tissues, the method comprising the steps of: a) arranging a spacer on a dental impression surface (ha, hib); b) arranging a base material (20) over said spacer; c) positioning the tooth part (7) in said base material (20); d) applying a compression force to compress the base material (20), tooth part (7) and spacer together to form a precursor denture (18); e) replacing said spacer of the precursor denture (18) with a soft lining material; and f) processing the precursor denture (18) and the soft lining material to form said soft lining denture (6); wherein the spacer comprises a spacer material (14), which spacer material (14) is resilient and displays a high toughness value.

9. A process for making a denture (6) according to claim 8, using the spacer according to any one of claims 1 to 7.

10. A process for making a denture (6) according to any one of claims 8 or 9, wherein the dental impression surface (lla, llb) imitates a patient's oral tissues (2 -4)

11. A process for making a denture (6) according to any one of claims 8 to 10, wherein a two-part mould casing (13) is used in the process for making said soft lining denture (6) Lc

12. A process for making a denture (6) according to claim 11, wherein the two-part mould casing (13) is made prior to step a) of the process.

13. A process for making a denture (6) according to any one of claims 11 or 12, wherein the two-part mould casing (13) comprises first (11) and second (12) parts each having a contact face (ha, llb/ 12a, 12b) with a peripheral cooperating edge region (llc, 12c)

14. A process for niaking a denture (6) according to claim 13, wherein when the two-part casing (13) is assembled with full contact between the cooperating edge regions (hlc, 12c), a fixed volume dental mould cavity is established.

15. A process for making a denture (6) according to any one of claims 13 or 14, wherein the replicate model of the patient's oral tissues comprises a first part (11) of the two-part mould casing (13)

16. A process for making a denture (6) according to any one of claims 13 to 15, wherein the method of forming the second part (12) of the two-part mould casing (13) comprises the steps of: I. arranging a "temporary denture" (16, 7) on the dental impression surface (ha, llb) of the first part (11) of the two-part mould casing (13); II. arranging a mould material (19) around the "temporary denture" (16, 7); III. applying a compression force to the mould material (19), the "temporary denture" (16, 7) and the first-part (11) of the two-part mould casing (13) to compress the mould material (19) around the "temporary denture" (16, 7); and IV. processing at least the mould material (19) and the first-part (11) of the two-part mould casing (13) to form the two-part mould casing (13)

17. A process for making a denture (6) according to claim 16, wherein the mould material (19) comprises a suitable plaster material.

18. A process for making a denture (6) according to any one of claims 16 or 17, wherein the "temporary denture" (16,17) comprises the tooth part (7), which is at least partly embedded in a palette-shaped member (16). c'J

19. A process for making a denture (6) according to claim 18, wherein the palette-shaped member (16) comprises a deformable or malleable modelling material.

20. A process for making a denture (6) according to any one of claims 18 or 19, wherein the palette-shaped member (16) is removable from said two-part mould casing (13) prior to step a)

21. A process for making a denture (6) according to claim 20, wherein the tooth part (7) is retained by the second part (12) of the two-part casing (13)

22. A process for making a denture (6) according to any one of claims 8 to 21, wherein the arrangement of the spacer on the dental impression surface (ha, lib) in step a) comprises applying a layer of spacer material (14) to the dental impression surface (ha, lib) before a "setting time" has lapsed.

23. A process for making a denture (6) according to any one of claims 8 to 22, wherein in step c), the positioning of the tooth part (7) is effected by the two-part mould casing (13)

24. A process for making a denture (6) according to any one of claims 8 to 23, wherein in step e) the soft lining material is arranged on the dental impression surface (ha, llb) to replace the spacer.

25. A process for making a denture (6) according to any one of claims 8 to 24, wherein the soft lining material is processed to form a flexible, rubber-like lining (21) Co 1

26. A process for making a denture (6) according to claim 25, wherein the processing of the soft lining material comprises heat curing.

27. A process for making a denture (6) according to any one of claims 8 to 26, wherein the soft lining material is Molloplast B (commercially available from Buffalo Manufacturing Co., Inc.).

28. A process for making a denture (6) according to any one of claims 8 to 27, wherein the processing step f) comprises hardening of the compressed base material (20) of the precursor denture (18) to form the rigid base (8) of the soft lining denture (6)

29. A process for making a denture (6) according to any one of claims 8 to 28, wherein the processing step f) comprises processing of said soft lining material into the soft lining (21)

30. A process for making a denture (6) according to any one of claims 8 to 30, wherein the processing step f) comprises bonding the soft lining (21) to the rigid base (8).

31. A denture (6) made using the spacer according to any one of claims 1 to 7.

32. A custom-made denture made according to the process of any one of claims 8 to 30. C\J

33. A spacer, a process for making a denture made using the same, a denture made using the same and a custom-made denture made using the same as substantially herein described with reference to the accompanying drawings.