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DISCUSSION OF RESULTS OF RESEARCH.

The question on comparative efficiency of direct and laboratory restorations of major defects of a coronal part of a tooth is a little shined in the literature. There are publications of an unequivocal orientation more often: one authors, underlining importance of observance

Technologies of application of composite materials, show high clinical effect of modern composites even in difficult clinical situations [3, 4, 12, 13, 16, 20, 21, 22, 27, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 43, 47, 49, 51, 59, 61, 62, 63, 64, 65, 66, 67, 69, 74, 75, 76, 77, 88, 93, 94, 95, 96, 97, 101, 105, 108, 109, 110, 112, 119, 123, 124, 128, 129, 130, 132, 134, 139, 141, 142, 145, 146, 153, 156, 159, 165]; other authors propagandise laboratory manufacturing vkladok, replacing defects of a tooth which recommend to make from ceramic and composite (keromernyh) materials [1, 5, 6, 10, 11, 18, 26, 34, 36, 37, 44, 48, 50, 52, 53, 58, 70, 72, 81, 100, 103, 105, 107, 120, 121, 131, 135, 142, 1449 147, 148, 149, 150, 151, 152, 157, 158, 161, 163, 166, 168 In Russia have found wide enough in comparison with ceramics application keromernye materials (Sculpture, Belleglas, Vectris, etc.) in view of smaller cost, more simple technology.

Direct and laboratory restoration of defects of firm tissues of a tooth compete with each other, and the choice the doctor of this or that technology depends on a skill level of the doctor and the tooth technician more, and is a little proved by scientific researches concerning durability, long term of those and other restorations.

We have set for ourselves a problem of detailed studying of a bodily machinery of composit seals and vkladok from keromera with the parallel analysis of the remote clinical results of both techniques.

For the analysis of the is intense-deformed condition in firm tissues of a tooth and in a material vkladki or seals we in the conditions of three-dimensional mathematical model of the bottom premolar tooth have simulated a cavity on type

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FASHIONS also applied on a tooth upright referred pressure 120 N.Harakter tooth lesions carious process and force of an occlusion correspond to practical clinical situations, and the sizes and fizikoyomehanicheskie properties of modelled objects are taken from references [70, 125, 154]. The tooth dentine was considered in model with

The characteristics inherent depulpirovannomu in a tooth.

C (RNTS «Kurchatovsky institute») pictures of the VAT of a tooth with a seal or vkladkoj were in colour displayed by the help of the computer program "WELDING" of the monitor accompanied by a scale of strains. Integrated strains, and also the compressing and stretching strains extending in three directions (medio-distal, shchechno-lingual, vertical were analyzed: h, at, z).

It is established (tab. 10), that in both compared cases the maximum strains in a dentine are localised in the field of an external surface of a neck of a tooth; thus strains basically compressing practically identical sizes (-17,7 MPA). Only at sealing by a composite there are small stretching strains in a crest of the pulpal chamber (+2,0 MPA).

In a tooth enamel the maximum strains almost to the same extent happen both compressing (-), and stretching (+).szhimajushchie strains in an enamel at sealing by a composite reach-51,5 MPA, and at use vkladki from keromera these strains it is less (-45,0 MPA). Compressing strains in both clinical cases become perceptible on an internal surface of an enamel.

Stretching strains in an enamel in both cases become perceptible in the field of enamel ledges on which, together with a dentine, medial and distal parts of restoration lean: at restoration by a seal +41,6 MPA, at restoration vkladkoj +37,3 MPA. In an enamel around vkladki it is less than strain, than round a seal: stretching - on 9,4 % compressing - on 12,6 %.

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In a seal and vkladke the maximum compressing strains, but also and the stretching strains making on size about half of sizes of compressing strains become perceptible basically. In both clinical situations the maximum compressing strains are localised in sredine an occlusal surface, and stretching - lengthways srediny a lateral surface of restoration. The maximum compressing strains are peer a seal-30,9 MPA, in vkladke-35,9 MPA. The maximum stretching strains are peer a seal +16,4 MPA, in vkladke +18,3 MPA. Thus, compressing strains in vkladke on 13,3 % more than in a seal; stretching strains in vkladke it is more on 11,6 % (fig. 13).

The major question in forecasting of long term of functioning of restoration of a tooth from various materials is comparison of the maximum strains to strength of tissues of a tooth and a material vkladki and seals.

In the chart in a drawing 13 strength of firm tissues of a tooth and restoration materials from literary data [70,125,154] are specified. Apparently on indicators of strains of compression all tissues and restoration materials have appreciable safety factor. At the analysis of strains of compression at both methods of restoration there is an essential safety factor in a dentine and the materials replacing defect in a tooth, but absence of safety factor pays attention to a stretching in enamel parts of ledges under medial and distal parts of a seal or vkladki (fig. 14). The augmentation of functional loads, weakening for any reasons of structure and mechanical properties of an enamel in these areas can lead otlomu or to microcracks of an enamel and destruction of restoration or caries development.

Table 10

Sizes and zones of the maximum strains in a tooth,

Restored by a composit seal or keromernoj vkladkoj (R = 120).

Research area Composite (seal) Keromer (vkladka)
Dentine -17.7

+2.0

External surface of a neck of a tooth a crest of the pulpal chamber -17.7

+ No

External surface of a neck of a tooth
Enamel -51.5

+41.6

Internal surface of an enamel ledges -45.0

+37.3

Internal surface of an enamel

Ledges

Restoration -30.9

+16.4

sredina an occlusal surface

sredina a lateral surface of a seal

-35.9

+18.3

sredina an occlusal surface

sredina a lateral surface vkladki


Fig. 13 Comparison of the maximum sizes of strains in a tooth with a seal from a composite and vkladkoj from keromera.

It is necessary to notice, that the disorder of limiting sizes of durability of tissues and materials under various references is rather great, and on some of them data are absent (for example, the elasticity limit on compression demineralizovannogo and an intact dentine) is not differentiated and it is necessary to be guided by logic comparisons. It speaks all about necessity of the further laboratory researches of physicomechanical properties of tissues and materials. Being guided by numerous positive clinical examples, we do not consider possible to speak about a primary overload of an enamel, ascertaining absence of a reserve of durability.

Fig. 14 Comparison of factors of safety factor (on a stretching) tissues of a tooth, a seal and vkladki.

As to safety factor of a dentine and restoration materials it is necessary to note advantage keromera in comparison with a composite. The appreciable stock in this clinical situation is shown by a dentine, a seal from a composite and vkladka from keromera have safety factor accordingly in 2,4 and 3,1 times.

It is necessary to specify, besides zones of the maximum strains, and other areas of a tooth and the restoration materials, subject to the appreciable

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To strains. It can be useful at the VAT analysis at change of a configuration and the sizes of a cavity in a tooth. So, in an enamel of the tooth restored by a seal from a composite, besides the maximum compressing strains on an internal surface of an enamel (it is more in the bottom part), there are compressing strains on an external surface of buccal and lingual hillocks (-27,4 MPA). The maximum stretching strains in the field of ledges are combined with strains on the bottom border of an occlusal layer of an enamel with a seal (+38,3 MPA). At tooth restoration vkladkoj there are stretching strains to +36,1 MPA in the specified zone; at tooth restoration vkladkoj compressing strains become perceptible on external surfaces of hillocks to-20,7 MPA.

In a dentine of a tooth with vkladkoj, along with the maximum compressing strains on a neck surface, there are strains to-7,4 MPA on a crest of the pulpal chamber and in the top third of root. At restoration by a seal compressing strains in the above-stated zones reach-8,8 MPA.

In a seal compressing maximum strains in the middle of an occlusal surface are combined with strains at transition in medial and distal clivuses of a seal and in the top layers of a seal (to-14,4 MPA); stretching strains are available in a seal on longitudinal borders of an occlusal surface (to +12,2 MPA).

In vkladke in the same areas corresponding to a seal, stretching strains to +7,7 MPA, compressing to-12,5 MPA become perceptible.

Thus, all layers of a tooth and restorations test raznonapravlennye alternating strains among which it is possible to note the zones comparable on size with the maximum. Apparently, expansion of borders of preparing of a cavity under a seal and vkladku, undercuts and the thinning of walls of a cavity, excess of a seal or vkladki on the area of ledges in a dentine and an enamel can show zones of "the second level of strains», along with zones of the maximum strains.

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The closest on the purpose and methodology of the mathematical modelling undertaken in given research, are Chumachenko E.N., Arutjunova S.D., Lebedenko I.J.'s calculations [125]. However, they had been used two-dimensional modelling of the bottom molar tooth with a cavity on II class and from results of comparison of an amalgam, a composite and ceramics it is possible to choose the basic conclusion: «... Irrespective of a used material, a strain in models restoration-dentin and a dentine-enamel» are concentrated on borders. The research undertaken by us gives more developed and detailed pictures of the VAT.

Biomechanical patterns quite correlate with results of the analysis of quality of restoration depulpirovannyh mandible premolar tooths after three years after the treatment termination.

For this purpose in Open Company clinic «Medservis M» are purposefully caused patients with the specified clinical situation; 109 seals and 81 vkladku were made by different doctors of clinic.

As a result advantages vkladok from keromera are established and typical disadvantages of that and other way of restoration (fig. 15) are taped.

For three years of functioning 22,1 % of seals from composite Filtek and 6,4 % vkladok from keromera Sculpture are lost. It is necessary to notice, that 12 teeth with absent seals had tooth split at neck level that makes 50 %. In 5 teeth with absent vkladkoj 3 also had deep otlom tooth walls (60 %).

The remained seals and vkladki had otkoly a restoration material accordingly in 14,1 % and 5,3 % of a teeth.

Disturbance of a regional adhering of a seal on this or that site of a cavity is noted at 100 % of a teeth, at use vkladki - at 42,1 % of a teeth. At use of electrodiagnostic device "STEEL" the average index of a regional adhering of seals has made 6,52 yo 0,5 mka and vkladok 3,9 yo 0,7 mka.

Fig. 15 Comparison clinical effektivnsoti seals from a composite and vkladok from keromera in premolar tooths with cavities of FASHIONS: an external circle - seals; an internal circle - vkladki

Erasability of a seal and constructional material is fixed at all teeth with seals and at 44,7 % of a teeth with vkladkami. The average degree of deleting estimated on measurements of the area of contact platforms with antogonistami, is more expressed at plombirovochnogo a material, than at keromera (accordingly 1,0 yo 0,4 мм2 and 0,6 yo 0,3 мм2).

In a teeth with the kept seals and vkladkami often enough became perceptible skoly enamels (accordingly 18,8 % and 10,5 %), and also an enamel and a dentine (3,5 % and 2,6 %).

The hanging edge of restoration in aproksimalnoj areas is noted only at 1 vkladki (1,3 %) and at 14,1 % of seals. Much more often in a teeth with seals was absent aproksimalnyj contact to a number standing teeth (31,8 % and 11,8 %). In aproksimalnom department it is possible to consider inadequacy of the form and a seal surface as one of the reasons of more frequent inflammation in interdental desnevom a papilla in comparison with vkladkoj: the local ulitis is noted at 42,3 % of a teeth with seals and у18,4 % of a teeth with vkladkami.

In both groups of comparison in three years suffered tsvetoustojchivost a restoration material, however, at seals the discoloration (including on restoration edge) became perceptible in 100 %, at vkladok in 57,9 %.

Coincidence of places having broken away and destructions of tissues of a tooth with zones of high strains is characteristic at biomechanical modelling: a neck of a tooth and the top quarter of a root, transition of the central part of a seal or vkladki in distal and medial on horizontal and vertical surfaces aproksimalnyh ledges. Erasability of seals and vkladok corresponds to area of the greatest strains in an average zone of an occlusal surface.

The reasons of the taped disadvantages of restoration of premolar tooths (cavities as FASHIONS) svetootverzhdaemymi composites and, in much smaller degree, keromerami are:

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- Presence of zones of high strains in firm tissues and restoration materials at functional loads of a restored tooth,

- Insufficient physicomechanical characteristics of materials (hygroscopicity, istiraemost),

- Wrong formation of a cavity in a tooth (a thinning of walls, undercuts, inexact formation aproksimalnyh parts of restorations).

Concerning two last reasons vkladki from keromera have objective advantages in connection with improved fizikoyohimicheskimi properties and in connection with laboratory conditions of their manufacturing (necessity of exact preparing of a cavity for reception of a cast and for possibility pripasovki vkladki).

In not numerous references on a theme of the given research we have received some acknowledgement to the received results. So, in Adilhanjana V. A's two-year-old research unsatisfactory results of sealing of premolar tooths and molar tooths (II class on Bleku) by similar criteria in 88,2 % of cases are resulted. At careful formation of a cavity the author has achieved a regional adhering to 3,2 yo 0,2 mka on electrodiagnostics of regional permeability. At the same time "uncontrollable" sealing gave an indicator of permeability 5,8 yo 0,4 mka [3].

In Shelemetevoj G. N's work the idea of non-observance of technology of sealing of a teeth by composites also is spent: in personal experience the share of unsatisfactory results has made 16 %, and at other doctors of 92 % for 5 years of observation. The indicator of regional permeability reached 5,7 yo 0,02 and 6,95 ±0,2 mka [128].

Amanatidi G. E underlines necessity for periodic polishing and current restoration of seals from composites, comparing variety of composites by clinical results in 2 years. The appreciable disorder of quantity of unsatisfactory results depending on plombirovochnogo a material [4] is resulted.

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Jakushechkina E.P. results digit 80 of % of unsatisfactory results in 18 months after sealing by different doctors (personal experience of 9,1 %). It draws a conclusion at the analysis of seals from a composite of various localisation on the most weak regional adhering of seals in cavities of type of FASHIONS: immediately after treatment electrodiagnostics has shown average value 1,06 yo 0,03 mka, and in 18 months 1,98 yo 0,05 mka [132].

At the same time, the researches devoted vkladkam, give more favorable forecast for clinical practice. Antonik M. M gives an indicator of unsatisfactory quality keromerov Targis and Artglass as 42 % and 35 % [5], Baranova I.A. in a year of use of microprostheses from the Esterfil-photo has established 13,3 % of unsatisfactory results. Kovalskaja T.V. a year later after application vkladok from polycrystalline glass at all has not found out any complications in a condition of a teeth and restorations [50].

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Scientific source BAHAREV LEONID JUREVICH. the Bodily machinery and clinical efficiency of intrastomatic and laboratory restorations of a teeth. The dissertation on competition of a scientific degree of the candidate of medical sciences. Moscow - 2004. 2004

Other medical related information DISCUSSION OF RESULTS OF RESEARCH.:

  1. CHAPTER 4. DISCUSSION
  2. Chapter 4 Discussion of the received results
  3. DISCUSSION OF THE RECEIVED RESULTS
  4. DISCUSSION OF RESULTS OF OWN RESEARCH
  5. Chapter 7 DISCUSSION of RESULTS of RESEARCH
  6. CHAPTER 8. THE CONCLUSION (DISCUSSION OF THE RECEIVED RESULTS)
  7. CHAPTER №5 DISCUSSION
  8. RESULTS OF RESEARCH AND THEIR DISCUSSION
  9. Chapter 5 Discussion of the received results
  10. Chapter 7 DISCUSSION of RESULTS of RESEARCH
  11. Chapter 7 DISCUSSION of RESULTS of RESEARCH
  12. CHAPTER 4. DISCUSSION of the RECEIVED RESULTS