aesthetic, considerations, denture, design, direct, partial, removable, retainers

AESTHETIC considerations IN THE design OF direct retainers removable partial denture. Od. Andres Eloy Sanchez Y.
Chair Professor of Removable Partial Dentures, UCV
Specialist in Prosthodontics.
Od. Jorge Vieira N. Dentist. Specialist in Prosthodontics.
Student Desiree R. Br Arenas of the last period of Dentistry VCU
SUMMARY
PPR hooks hold a cosmetic problem, which can be minimized through proper analysis and design of the case. The use of attachments has the advantage of excellent cosmetic results obtained by removing the buccal retentive arm hooks, but the use of these represents additional work for the dentist and greater cost to the patient, added to this, the use of these additions is a controversial and confusing issue in the specialty because of the multitude of alternatives, such as attachments intracoronal, extracoronal, intracanal, extraradicular, precision, semiprecision, rigid and elastic. In this sense, in this review are some aesthetic considerations in the design of direct retainers and the nomenclature, classification and indications of the different types of supplies used as retainers of PPR and criteria for selection.
KEYWORDS: Hair, retainers, removable partial denture.
ABSTRACT
The Lack of esthetics produced by the clasps in removable partial denture the minimized thru Should Be Adequate analysis and design. One way is to Achieve Eliminating the esthetics more retentive clasps, using precision attachments or semiprecision.
This paper Analyses the esthetics in the clasps, and Indications of the League table attachments in removable partial denture the.
Received: 05/05/2000 Accepted for publicación18/09/2000
I. INTRODUCTION.
The demand for replacement of missing teeth with a prosthesis, is stimulated by the desire to improve the appearance, function, or replace an existing denture unsatisfactory. The patient's level of demand with respect to oral function depends largely on geographic, cultural and socioeconomic in non-industrialized societies patient demands tend to focus on chewing and no pain, whereas in industrialized countries main concern is the social aspect of communication in these countries in recent decades has become an increasingly important the look and feel (1).
The cosmetic dentistry has evolved in the era of the nineties to a multidisciplinary component of total facial aesthetics, which requires an integration of the stomatognathic system, so in addition to the teeth with features of shape, color and position, should be included other aspects such as the gums and surrounding soft tissues to create a harmonious smile as part of the look (2).
Harmony is the balance in a composition optics and dentistry, a composition of this type is the interrelationships that exist between the face, lips, gums, teeth and personnel radiation. When installing the prosthesis to the patient, the color might be ideal, but if the shape and structure of the prosthesis are not in harmony with the facial composition, will present an aesthetic failure (3).
The glossary of prosthodontic terms (4) defines aesthetics as on the study of beauty and sense of beauty. Lafrate Dallorca and (3), they add, the beauty is a feeling of harmony and balance conditioned by time and culture in which we live.
The prosthodontic treatment included the restoration of aesthetics, as well as restore function, comfort and health of the patient (4). Achieving these objectives will depend on a combination of artistry and power of observation (5).
For the patient are often more important aesthetic and phonetic aspects of removable partial denture (PPR) that function, thus providing ideal esthetic results can be one of the essential aspects of the treatment plan (6,7,8) .
The design of removable partial denture must meet three basic requirements: support, stability and retention, but the patient also expected to improve their chewing restoration, phonetic and aesthetic addition to the prosthesis maintain the health of the remaining oral tissues ( 7). In this regard, Smith (9) states that a simple way to analyze aspects of design and construction of a PPR that involves aesthetics, is to consider the various elements of the prosthesis. In this regard we consider the objective of this review to analyze the aesthetic considerations in the design of direct retainers of the PPR
II. REVIEW OF THE LITERATURE
The aesthetic factor is not always considered when designing a direct retainer, which can result in a prosthesis questionable from this point of view (7). Fischer (6), refers to the direct retainers must meet not only functional requirements but also must be acceptable from the aesthetic point of view, in this sense the most important is the design of the visible elements of direct retainer.
Aesthetic results can be achieved with more expensive methods that PPR held with hooks, using attachments in crowns, which can completely avoid that look retainers, however, the cost to the patient and the dentist's work much higher (5).
Direct retention alternatives are: PPR rotational axis of insertion due to the fact that certain extracoronal retainers can be removed without affecting the mechanical requirements of the same (10) and treatment with overdentures and implants, through which visible fasteners can eliminate the use of attachments button, bars and other forms of attachments (6.2).
l. Extracoronal RETAINERS (HOOK)
Although the partial denture retained by hooks has disadvantages, it is possible that for reasons of economy and time spent, continue to be used because it can provide a physiologically healthy treatment for most patients who need PPR (11). Extracoronal conventional retainers are the most commonly used because of its low cost and versatility in application, despite its poor cosmetic appearance (12).
The fact that the hook arms are only objectionable if they are visible during normal use, it has not been properly valued. The dentist should explain to your patient who is not a "normal" situation when using a mirror and lip retracts under the intense lighting of the office to locate precisely the retainers of the PPR extracoronal
The obligation of the dentist is to establish a planning and design of the metal structure, this involves remodeling of the teeth, the surveyor analysis and selection of direct retainers less visible (9). In addition to Goldstein (5) states that the technician must provide the specific design that includes factors such as the lip line and smile.
The use of hooks in the anterior region presents an aesthetic problem, however, can be minimized with proper model analysis and preparation of the mouth, so to pinpoint the location of origin and far enough below the occlusal surface to avoid poor aesthetic effects.. (5) ( [Only registered and active users can see links. or Thanks]
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AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
When restorations are indicated in the preparation of the mouth, the main consideration should be to allow the lower contours display hooks. It also states that it is possible to show less metal hooks if placed in the disto-gingival position of the tooth surface, this is possible by selecting the path of insertion or the modeling of the restorations (5). Small changes in the inclination of the model during the selection of the insertion axis can be made ​​to place the components of PPR in less exposed areas, so as not to interfere with the aesthetics or sacrifice the rest of the determinants of the insertion axis ( 11.13).
The literature refers to some aesthetic considerations for the design of retaining extracoronal (hooks), so for example in the design of retainers such circumferential line has been established in general, the arms of the hook should be kept as short thin as functionally possible (5) and must be located entirely in the cervical third of the abutment (9).
Within the group of retainers circumferential Goldstein (5), refers to withholding further action, the hitch mesiodistal and combined cast-forged retainer that is most commonly indicated in PPR distal extension. The latter has a wrought-wire retentive arm that allows use in smaller diameter cast a hook without the risk of fracture, its rounded shape increases the refraction of light, making the metal less visible (11.5).
As for the bar retainers, Goldstein (5) states that the hooks retentive as T or Y, only one end is actually in the retention area, therefore, for aesthetic reasons or requirements the remaining end may be eliminated if the contour of the crown and allows the district is not compromised. RPI hook meets the highest esthetic requirements with a minimum alveolar lining (5) ( [Only registered and active users can see links. or Thanks]
[فقط الأعضاء المسجلين والمفعلين يمكنهم رؤية الروابط أو شكرا] ).
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Fig.2. By using the RPI retainer in cases of lower jaw, leads to better aesthetics.
The I-beam with a low lip line is acceptable from the aesthetic point of view, but has mechanical limitations in relation to the constituency in dogs (9). Hansen et al. (12) report that the convenient placement of the retentive arm in the mesiobuccal region, often resulting in adverse aesthetics, thereby presenting a modification of the disto-buccal flange of an upper canine used as a pillar for placement in that area of the retentive arm I, improving the aesthetics, the insertion axis and providing a resistance to distal movement of the PPR ( [Only registered and active users can see links. or Thanks]
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AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Fig.3. Changing the disto-buccal flange of the canine to the location bar aesthetic I.
This modification can be achieved by developing a cast inlay retained by pins, the construction of a metal-porcelain crown or through composites.
In the premolars, the placement of the retentive arm in the disto-buccal improved aesthetics, however it is essential to take a critical caution, in the lingual should be provided with the constituency and reciprocation necessary (9).
Belles, (8) describes an alternative retaining an aesthetic anterior incredible that consists of a wrought wire welded into a channel that is made ​​into a major connector of PPR This hook called "Twin-flex" or "Spring clasp" is flexible so that the torque decreases as the distal extension base is depressed. The ability to set the hook and its axis of insertion gives an excellent alternative to conventional design for holding adjacent to an anterior edentulous space.
The retentive element of "Twin-flex" is a 19-gauge wrought wire that is adapted to a retention of 0.010 "on the tooth surface adjacent to the edentulous space, similar to the design of PPR rotational axis of insertion. ( [Only registered and active users can see links. or Thanks]
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AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Fig.4. Outline of the Twin-Flex clasp. Wrought wire connector is included in the most strained.
The disadvantages of this technique include: increased thickness of the major connector on the wire hook, extra laboratory steps, with an increase in the cost and difficulty of repair in the event of a fracture (8).
Santana-Penin and Mora (14) reported a new procedure for making the system "Twin-flex" that eliminates the disadvantages described above, because the hook is not soldered to the metal structure, but is located within the thickness acrylic resin base.
The design of the retainer "Twin-flex" reduces the risk of orthodontic tooth movement pillar with other lingual retainers using retention as the design described by Pardo-minded and Villandiego Ruiz (15) which is located in a retainer lingual face of a full crown prepared with the following characteristics: a wedge-shaped break from mesial to distal and gingival retentive undercut located at rest, on which are located the elements that produce retention, stability and support ( [Only registered and active users can see links. or Thanks]
[فقط الأعضاء المسجلين والمفعلين يمكنهم رؤية الروابط أو شكرا] ).
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Goodman, reported by Regan and Roland (16) Equipoise system developed for use in first premolars of aesthetics and preservation of the pillars. The design of the retainer includes a mesio-occlusal rest which extends an arm around the tooth to a retention area located on the disto-buccal. The lack of reciprocation and retention may be a problem with this retainer like the sacrifice of a considerable amount of tooth structure of adjacent teeth. ( [Only registered and active users can see links. or Thanks]
[فقط الأعضاء المسجلين والمفعلين يمكنهم رؤية الروابط أو شكرا] ).
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Other methods of direct retainer with the aesthetic benefits which are obtained are the TACH-EZ (Whaledent Int.) Anchor and ZA (Metrodent LTD) Wryht described by (17) and the addition IC (APM-Sterngold) described by Regan and Rold (16) ( [Only registered and active users can see links. or Thanks]
[فقط الأعضاء المسجلين والمفعلين يمكنهم رؤية الروابط أو شكرا] ). The design of these systems consists of a plunger that fits a hold on the proximal surface of abutment tooth adjacent to edentulous space, with the advantage of precision attachments that do not require the preparation of a restoration on the abutment tooth. When PPR is inserted, the spring plunger is depressed in while passing through the height of contour of the tooth, then set the retention under the height of contour (18). These additions complicate the placement of artificial teeth due to the space they occupy, if vertical space is minimal, the aesthetics of the artificial teeth may be compromised (16).
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
PPR with rotational axis of insertion (ERI) is a tooth-borne prosthesis that sits in the mouth with a foothold and by a movement of rotation causes the settlement of the rest of the prosthesis, allowing a rigid metal structure act as a retentive element located in the proximal aspect of the tooth adjacent to edentulous gap, the implementation of this design is limited to tooth-supported cases of class III and IV Kennedy. The purpose of generating support, stability and retention in an area of ​​partially edentulous arch without the need for retainers provide benefits extracoronal biological, mechanical and aesthetic considerable. (Fig. 8, [Only registered and active users can see links. or Thanks]
[فقط الأعضاء المسجلين والمفعلين يمكنهم رؤية الروابط أو شكرا] , [Only registered and active users can see links. or Thanks]
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AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
8A
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Figure 8b
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Figure 8c
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Figure 8d
Figure # 8. Case report. Ppr treatment with rotational axis of insertion.
A. Class III modification 1 case of Kennedy High.
B. Design of metal structure of the PPR at 13 and 23: Board to achieve palatal and proximal retention in the anterior. 17 and 27: Retaining circumferential.
C. Case finished occlusal view.
D. In anterior teeth are not observed direct retainers of the PPR
ERI PPR is considered a technical design-sensitive, but this factor can be controlled if proper planning and good communication with the dental technician (10).
Krol in 1981, proposed two design categories ERI PPR is based on the location of the center of rotation and its clinical applications. The clinical patterns of class I are mainly used for the restoration of posterior edentulous areas, while category II are specific to the anterior edentulous area and unilateral edentulous areas (10).
2. -ATTACHMENTS
The biggest advantage of using attachments such as retainers PPR is the excellent cosmetic result by eliminating the buccal retentive arm, however, the cost to the patient and work for the dentist is much higher (5.19).
The use of attachments in PPR is an issue that can not be neglected as one of the most confusing and controversial of the specialty because there are many views and trends and in many cases are placed anchors without knowing why or as the body reacts against the action of the same (19). As such, this review presents some considerations on the nomenclature, classification, indications, types of supplies used as retainers of PPR and criteria for selection.
Attachment: A mechanical device used for fixation, retention and stabilization of the denture. Consists of one or more parts, made of plastic or metal.
Precision attachment: This is a prefabricated component device specific tolerance to known alloys. The hardness of the two or more components is carefully balanced to control wear.
Semiprecision Fixture: A device that is manufactured in the laboratory or partially made ​​from plastic forms. The accuracy depends on the skill of the technician.
Extracoronal Attachment: A device located entirely outside the contour of the crown.
Lntracoronal Attachment: A device that connects the prosthesis to the crown with a point within the contour of the tooth.
Elastic Attachments: These are additions to a spring or other mechanical device that allows settlement of the prosthesis under mastication. Some elastic attachments using the natural elasticity of the tissues to return the prosthesis to his passive position after chewing.
(Taken from the Glossary of Terms Academy of Prosthodontics, 1994 and Staubli, 1991).
According to these definitions attachments can be classified according to their accuracy and semiprecision manufacturing and by their function in elastic and inelastic. ( [Only registered and active users can see links. or Thanks]
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AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Figure # 9. Classification attachments
2.1. Intracoronal Precision Attachments:
It refers to the prefabricated type intracoronary device closure, built with compatible materials that can be used as a retainer of a PPR or a seal between two or more sections of a fixed partial denture (20). ( [Only registered and active users can see links. or Thanks]
[فقط الأعضاء المسجلين والمفعلين يمكنهم رؤية الروابط أو شكرا] ).
Directions:
A. Aesthetics:
The main advantage of an attachment of precision intracoronal as a retainer for a PPR is the aesthetics by eliminating the vestibular hook arm (5,19,21). Precision attachments provide what is necessary to build a device that provides aesthetic partial denture retention without injuring the supporting teeth (20).
When there are problems in the region of the mouth in the direction of resorption of alveolar bone where a fixed prosthesis would not give the necessary aesthetic level, the PPR contributes to support the muscles of the lips and restores its contour. In these cases the aesthetic of the PPR is in addition to the use of some fixtures in the front of the mouth (19).
B. In PPR tooth-supported:
They are excellent anchors when large gaps exist where contraindicated edentulous using a fixed prosthesis and the attachment of precision itself provides the basic functions of an anchor or hook extracoronal, ie, retention, reciprocation, support and guide map for the course insertion (19).
Attachments intracoronal rigid precision should not be indicated in PPR dentomucosoportadas Class I and II Kennedy, unless stressbreaker used, because they are rigid and all horizontal movements of inclination and rotation of PPR are transmitted directly to the abutment tooth . However, in cases of attachment dentomucosoportados use in conjunction with the concept of a stable, fully supported in the tissues, eliminates the forces exerted on the abutment teeth (18).
The literature describes ways intracoronal precision attachments elastic can be used in PPR dentomucosoportadas, as in the case of attachment of arch Cross Crismani Roach and elastic. ( [Only registered and active users can see links. or Thanks]
[فقط الأعضاء المسجلين والمفعلين يمكنهم رؤية الروابط أو شكرا] ).
C. In fixed partial denture (FPD):
Can be used as semi-rigid connectors (knuckle joint) of PPF to join sections and facilitate the parallel supporting teeth, to simplify the cementation and avoid twisting of metal-porcelain restorations span the arc. It also indicates when there is a segment of the PPF with a questionable prognosis, because if you lose you can replace that section with a PPR held with attachments (20).
To get a clearer idea of ​​its indications is important to consider the advantages and disadvantages. A major advantage is its thickness, which is less than a retainer hook, since by reducing coverage periodontal extracoronal have less commitment and a better control of hygiene do not cause trauma on the abutments during insertion and removal of PPR, as with the designs of evil made ​​PPR hooks, plus the forces are better distributed in the direction of long axis of the tooth, so the structure is better preserved and periodontal support (19.20).
Its duration is excellent if well built and in parallel and requires minimal maintenance if your placement is correct (19). When the male portion of fractured fixture is easy to repair the machine, selecting the size and shape of the attachment originally used to fit the female or matrix (20).
Among the disadvantages or limitations include: wear long-term appears, although it may be activating it requires more time for preparation and adjustment, representing an economic burden for the patient requires the preparation of abutments adjacent teeth in cases of with large pulps requires endodontic treatment, warrants the existence of a long clinical tooth crown pillar, to locate the required attachment of 7mm in length (5 mm minimum length and 2 mm separation of the gingival margin) (19,20).
Do not use previous precision fixtures combined with hooks on the rear pillars, because no difference in the types of movements of the retainers, precision attachments only move vertically, while the hooks are deformed laterally to pass through the height of contour (20).
2.2. Attachments semiprecision intracoronal of inelastic-(blockers):
Blatherfein, reported by Zinner (22) established that although precision retainers are more sophisticated mechanisms that support semiprecision constitute a strict discipline and do not have the versatility to effectively monitor clinical variations with different faces the dentist.
The blocking connection is the design semiprecision built more frequent and easier to perform in the laboratory. There are four basic types of breaks semiprecision: 1. - Dovetail, 2. - Circular, 3. - Notches, and these three are the locking type and 4. - Rectangular or non-blocking type breaks PPR for distal extension (22). ( [Only registered and active users can see links. or Thanks]
[فقط الأعضاء المسجلين والمفعلين يمكنهم رؤية الروابط أو شكرا] ).
The PPR semiprecision is particularly useful in cases of abutment teeth short; can be constructed with a variety of ways, giving varying degrees of rotation and reciprocity (5). This type of attachment is also used as non-rigid connections of fixed prosthesis. ( [Only registered and active users can see links. or Thanks]
[فقط الأعضاء المسجلين والمفعلين يمكنهم رؤية الروابط أو شكرا] ).
Semiprecision system does not give rise to adjust the retention, thus providing good support and stability, support comes from the relationship between the gingival floor of rest and seat support, and stability is given by the ratio between the parallel sides of the walls of the rest. The retention can be obtained through a semicircular lingual management arm ended in a horizontal groove, a retaining arm in a groove finished casting, carved semicircular arm 14 gauge, closing bar or tube device (22).
Connections precisely and only provide semiprecision blockers do not allow vertical movement and rotation, thus in a situation of PPR distal extension, especially an event that occurs lower in the rotation of the prosthesis in the three axes of space, it must try to get a stress-breaking action. Situations that require a stress breaker design are those in which there is a bad bad periodontal support and residual ridges, or good and bad periodontal support residual ridges, these are situations where semiprecision indicate non-blocking connections (22).
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
2.3. Attachments semiprecision intracoronal of elastics (not blocking):
It is a support system that provides intracoronal leverage and uses a class II base intracoronal support non-blocking. This type of occlusal support intracoronal rectangular shaped and placed in the distal proximal surface of the abutment (23).
This connection was introduced by Dr. Ferdinand Neurohr in 1930 and was named Neurohr closing spring. Its production uses the spindle # 2 William's Neurohr, which has a floor groove that maintains reciprocity with the support system for non-blocking, has a gap of 1 mm deep and 1 mm wide with a break converged 4 mm and a ledge of 1 mm. Dr. Bruce Clark subsequently used Neurohr chuck clamping arm with a thick tongue for greater stability; Franklin Smith used a forged gold wire 20 gauge located in a disto-vestibular depression. In 1949, Dr. Morris Thompson of California took these designs and the support pin made ​​of his own name by varying the dimensions of the mandrel Neurohr. (23) ( [Only registered and active users can see links. or Thanks]
[فقط الأعضاء المسجلين والمفعلين يمكنهم رؤية الروابط أو شكرا] ).
Wand describes a redesign of Thompson which is the use of a supporting arm or wire ball forged 0.032 "located in the distal retention and Blatterfein proposes the use of an mesial connector, so that the retentive arm is directed from mesial to distal and distal ends in retention (23).
The retainer bolt Thompson is a device that combines semiprecision intracoronal of most of the advantages of prefabricated attachments and also provides indirect retention and action of stress breaker so that PPR can be used in mesial or distal extension. Crowns can be used in relatively short, since it offers outside holding the tooth, this device can be varied to meet the aesthetic requirements of each case (5). ( [Only registered and active users can see links. or Thanks]
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AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Fig 11th
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Fig.11b
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Figure 11c
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Fig 11d
Fig # 11. Clinical case of Kennedy Class II which uses retainer Thompson.
A. Case treated with metal ceramic fixed partial denture from 17 to 23 (where you put the retainer Thompson).
B. Steel Structure Design:
- Connector largest turtle or horseshoe type.
- Direct retainers: Thompson in 23, circumferential clasp in 17
- Indirect retainer at 24.
- Base metal combined acrylic.
C. Thompson Detail additive which observes the wrought-wire retentive element into a ball.
D. Superior aesthetic appearance of PPR. The DPR is a lower denture with conventional hooks.
Splinting of abutment teeth is recommended whenever possible in all uses of intracoronal support systems. Studies have shown that the photoelastic Thompson retainer force induces patterns more appropriate when the abutments are splinted compared with other means of connection and intracoronal extracoronal precision (18).
2.4. Extracoronal Attachments:
These devices have most of its mechanism outside the tooth contour. As a rule, buccolingual require less space and are used when intracoronal attachments are contraindicated. It avoids making an excessive grooming in the proximal surface of abutment teeth. It is necessary to splint the remaining teeth to get extra support when using these devices (5).
Extracoronal connections are used in the construction of PPR to get a stress breaker action. This type of device can be used in cases of Class I or Class II Kennedy whose remaining teeth are periodontally weakened. These connections are used to reduce the forces on the abutments and transfer them to edentulous areas. These additions provide a primary retention function, but do not support or stability (24.23).
Extracoronal connections do not allow control of the distribution of forces. They are elastic and allow vertical movement or rotating hinge, or some combination of all three. When using these connections to well-defined residual ridges, buccal and lingual sides of the bases stabilize the prosthesis. However, in a poor rim, there is rotation and torque on the abutment teeth, creating periodontal and endodontic (24).
Attachments extracoronal have the following disadvantages: lack of stability, inadequate control of the distribution of forces between the toothed and edentulous areas, problems and maintenance issues exceeded, resulting in increased spending for the patient (18).
According Boitel, quoted by Wolfe (24), extracoronal connection systems have been classified as follows: A. Connect the male rigid welded to the column. B - Connecting with the male band welded to the column. C. - Connections bar.
Las conexiones rígidas extracoronarias no proporcionan acción rompefuerza, por lo tanto, crean un tipo de restauración en extensión que puede producir trastorno periodontal en los dientes pilares, con la consiguiente reducción del pronóstico general de la prótesis terminada. ( [Only registered and active users can see links. or Thanks]
[فقط الأعضاء المسجلين والمفعلين يمكنهم رؤية الروابط أو شكرا] ). Las conexiones extracoronarias elásticas fueron desarrolladas para contrarrestar el efecto de torsión de la prótesis en extensión sobre los dientes pilares al permitir un movimiento en bisagra o rotatorio entre la base de la dentadura de extensión distal y el diente pilar.
Las conexiones de barra en PPR tienen que ser consideradas cuando hay pocos dientes remanentes con periodonto reducido o un pronóstico reservado. Estas conexiones pueden utilizarse para una ferulización en arcada cruzada entre las coronas pilares. Las conexiones en barra se dividen en dos grupos: uniones en barra y unidades de barra rígida. La primera permite pequeños movimientos entre los dos componentes y la segunda proporciona ferulización de los dientes pilares remanentes (24) . ( [Only registered and active users can see links. or Thanks]
[فقط الأعضاء المسجلين والمفعلين يمكنهم رؤية الروابط أو شكرا] .)
3. -SOBREDENTADURA
Las sobredentaduras son otra alternativa para trabajar sin retenedores visibles (6) . La sobredentadura parcial es definida como la prótesis que es soportada y retenida por dientes remanentes y tejido. Estos pilares o implantes pueden o no estar conectados a la prótesis a través de aditamentos (25) . Otros nombres que se le dan a este tipo de prótesis son: prótesis híbridas, sobredentadura, prótesis telescópica, prótesis total dentosoportada, prótesis biológica y prótesis sobrepuesta (26) .
Las ventajas con este tipo de tratamiento protésico pueden clasificarse en tres grupos: técnicos, emocionales y biológicos (26) . Las ventajas desde el punto de vista técnico son: mayor facilidad para enfilar los dientes artificiales con fines estéticos y mayor estabilidad y retención del aparato. En tal sentido, Castleberry (27) refiere que los arcos parcialmente edéntulos pueden presentar dientes residuales espaciados, rotados o desplazados que limitan el enfilado normal o estético de los dientes artificiales. Estos dientes residuales pueden ser tratados endodónticamente, seccionados en su corona clínica y usados como soporte para la sobredentadura. Desde el punto de vista emocional, los pacientes aceptan mejor una prótesis removible cuando saben que todavía conservan uno, varios dientes o raíces naturales. Biológicamente, la retención de dientes o raíces ayuda a preservar los rebordes edéntulos remanentes, mantiene la capacidad neuromuscular del paciente y la capacidad propioceptiva de los dientes que soportan el aparato. En tal sentido, Fenton (28) en una revisión de 10 años de sobredentaduras concluye que los pacientes pueden masticar mejor, sus rebordes no se resorberán tan rápidamente y que la prótesis es más estable y retentiva.
Los pilares de la sobredentadura pueden ser tan efectivos en el soporte de las prótesis parciales como en las totales. Los dientes pilares estratégicamente ubicados minimizan el movimiento de una PPR, por lo cual se reduce la tensión aplicada sobre los dientes remanentes y los rebordes residuales (29) . [Only registered and active users can see links. or Thanks]
[فقط الأعضاء المسجلين والمفعلين يمكنهم رؤية الروابط أو شكرا] [Only registered and active users can see links. or Thanks]
[فقط الأعضاء المسجلين والمفعلين يمكنهم رؤية الروابط أو شكرا] , [Only registered and active users can see links. or Thanks]
[فقط الأعضاء المسجلين والمفعلين يمكنهم رؤية الروابط أو شكرا] , [Only registered and active users can see links. or Thanks]
[فقط الأعضاء المسجلين والمفعلين يمكنهم رؤية الروابط أو شكرا]
La corona telescópica constituye un método de fijación de la sobredentadura. El concepto de corona telescópica puede utilizarse con una preparación de la corona clínica; este método es más económico, pero precisa un gran pulido de la superficie dentaria, mantenimiento con fluoruro y atención asidua a la higiene. Otro método constituye la fabricación de un colado único que se elabora con la convergencia deseada para que actúe como un elemento de apoyo (30) .
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Fig. 12a
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Fig. 12b
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Fig. 12c
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Fig. 12d
Fig. 12. Caso de Sobredentaduras
A. Paciente con Dentinogenésis imperfecta
B. Preparación del maxilar superior con cofias coladas en los dientes remanentes para sobredentadura total superior.
C. Preparación del maxilar inferior:
- Coronas coladas en el 38 y 48.
- Coronas metal-cerámicas en el 33 y 43.
- Cofias coladas en el 34, 35, 44 y 45.
- Recubrimiento con vidrio ionomérico en el 31, 32, 41 y 42.
- Estructura metálica de sobredentadura parcial removible inferior con eje rotacional de inserción para evitar la colocación de ganchos en coronas del 33 y 43 por razones estéticas.
D. Vista frontal del caso terminado.
La ventaja de la corona telescópica con respecto a la sobredentadura convencional es la mayor estabilización y retención de la dentadura cuando se usan dientes vitales o no vitales, sin pernos, ni tornillos (30) . Las indicaciones de este tipo de tratamiento son: conservación de la dentición remanente, reposición de dientes ausentes y estabilización oclusal (31) .
Los aditamentos para sobredentaduras proporcionan orientación, retención, estabilidad y comodidad para el paciente. En este tipo de sobredentadura se emplean aditamentos en botón, en barra y otros aditamentos auxiliares. El objetivo más importante en la selección de los aditamentos es la manera como se transfiere la fuerza de tales dispositivos a través de los pilares y estructuras adyacentes (32) .
Aditamentos en botón : constituyen una serie de botones de precisión que constan de dos o más elementos; uno que forma parte de una cofia apoyada en una espiga y la otra de la prótesis; pueden ser rígidos o elásticos. Constituyen una unidad de soporte autónomo, independiente de otras similares; pueden utilizarse aislados o en grupo, bilateralmente, por lo general sobre raíces de los caninos o premolares. De esta forma se obtiene máxima estabilidad, aunque pueden utilizarse en cualquier otro lugar de la boca. Un aspecto fundamental para la elección del aditamento es la consideración del espacio interoclusal (30) . ( [Only registered and active users can see links. or Thanks]
[فقط الأعضاء المسجلين والمفعلين يمكنهم رؤية الروابط أو شكرا] ).
Aditamentos en barra: constan por lo general de dos parte; la barra y algún tipo de clip o elemento de retención. Las barras se clasifican además en rígidas y elásticas. La barra está unida a dos o más cofias apoyadas en tornillos o espigas o coronas y el tipo clip forma parte de la prótesis removible. Los sistemas de barra ofrecen también ferulización (32) . ( [Only registered and active users can see links. or Thanks]
[فقط الأعضاء المسجلين والمفعلين يمكنهم رؤية الروابط أو شكرا] )
Aditamentos auxiliares: los aditamentos auxiliares utilizados para el apoyo de la sobredentadura constan de diversos tipos de conectores de retén con muelle, tornillos y otros aparatos de retención habituales. La mayoría de estos se utilizan para obtener una retención adicional sobre una corona telescópica modificada o un implante en botón. Dentro de este grupo se incluyen otras formas de retención como son los retenedores intrarradiculares y extrarradiculares (30) . ( [Only registered and active users can see links. or Thanks]
[فقط الأعضاء المسجلين والمفعلين يمكنهم رؤية الروابط أو شكرا] )
Entre los aditamentos intrarradiculares está el "Zest" cuyo elemento hembra es cementado en la raíz residual posterior al tratamiento endodóntico y el elemento macho de nylon es incorporado en la sobredentadura fijándose a la caja hembra dentro de la raíz (32) . Este aditamento se indica cuando existe un mínimo de nivel óseo de 5 mm y jamás debe utilizarse como un dispositivo para soportar cargas (33) . De los aditamentos extrarradiculares el "O-so" es el sistema de botones de carga más suave usado para la sobredentadura estándar. Este método cuenta con empaques (O-rings) de silicona enclavados en la sobredentadura con el botón macho correspondiente colocado en la raíz residual y un grado fijo de resiliencia (32) . Este dispositivo puede ser utilizado o no como sistema de carga, dependiendo de la integridad periodontal de la raíz retenida y de la condición del reborde (33) .
Los sistemas de imanes intrabucales son utilizados como elementos de soporte y retención de las sobredentaduras parciales removibles. Ellos limitan las fuerzas transmitidas a las raíces, debido a que no pueden exceder su valor óptimo de retención contra el desplazamiento vertical. Los imanes pueden deslizarse sobre sus armaduras, con limitación de la fuerza transmitida durante la oscilación y los movimientos de rotación protética (34) .
Los aditamentos de precisión, semiprecisión y otras formas de retención de PPR son utilizados con poca frecuencia en los casos tratados en la Facultad de Odontología de la UCV y en los casos de la práctica privada de Caracas, Venezuela (35) ; coincide con esta observación lo evidenciado por Curtis y col. (36) en los Estados Unidos. Por otra parte Owall y col. (37) refieren que en Alemania existe un claro predominio en la utilización de aditamentos de precisión, barras y prótesis telescópicas como medio de retención de PPR comparado con otros países como Estados Unidos, Polonia y Suecia.
La preferencia de los odontólogos hacia la utilización de determinadas formas de tratamientos sin duda está ampliamente influenciada por el entrenamiento del graduado y las posibilidades financieras de la población en la que se trabaja. Así por ejemplo en Alemania el 90% de la población está incluido en un sistema de seguridad social que cubre el 60% del costo del tratamiento, incluyendo formas complejas de elementos retentivos de PPR (37) .
III.- CONCLUSIONES
La restitución estética es un objetivo del tratamiento prostodóntico que frecuentemente se ve afectado por el diseño de los retenedores directos de la PPR, dicho factor debe ser considerado sin sacrificar otros requisitos funcionales del tratamiento protésico.
La PPR retenida con ganchos constituye un problema estético, que puede ser minimizado a través de un adecuado análisis y diseño del caso, al seleccionar retenedores como el combinado (colado-forjado), el retenedor RPI y otras alternativas de retención como son el gancho Twin-flex, el anclaje ZA, y la PPR con eje rotacional de inserción.
La utilización de aditamentos como retenedores de PPR ofrece la ventaja de obtener excelentes resultados estéticos al eliminar el brazo retentivo vestibular de los ganchos. La utilización de estos aditamentos es un tema controversial y confuso en la especialidad debido a la multitud de alternativas, como son aditamentos intracoronales, extracoronales, intrarradiculares, extrarradiculares, de precisión, de semiprecisión, rígidos y elásticos.
Otra opción para la elaboración de la PPR sin la utilización de retenedores visibles la constituye la sobredentadura parcial removible con aditamentos en botón, barras y otros métodos auxiliares que proporcionan orientación, retención, estabilidad y comodidad para el paciente.
Anexo #1
Aditamentos intracoronales de precisión rigidos
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Anexo # 1
Aditamentos intracoronales de precisión rigidos
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Anexo # 2
Aditamentos intracoronales de precisión elasticos
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Anexo # 3
Aditamientos intracoronales de semiprecisión rigidos
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Anexo # 4
Aditamentos intracoronales de semiprecisión elastico
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Anexo # 5
Aditamento extracoronales
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Anexo # 6
Aditamentos a barra
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Anexo # 7
Aditamentos en botón
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
Anexo # 8
Aditamentos intrarradicular y extrarradicular
AESTHETIC CONSIDERATIONS DESIGN DIRECT RETAINERS
IV.-REFERENCIAS BIBLIOGRAFICAS
1. - Owall, B., Kayser, A., Carlsson G. (1997). Odontología protésica, principios y estrategias terapéuticas. Editorial Mosby. Madrid.
2. - Goldstein, R. and et al. (1994). The changing esthetic dental practice. JADA. 125 : 264-70
3. - Dalloca, L., Lafrate, R. (1998). Estética: armonía sin simetría. Quintessence técnica (ed. esp.) 9 : 264-70.
4. - Glossary of prosthdontic terms. (1994). J. Prosthet. Dent. 71: 41-112.
5. - Goldstein, R. (1980). Estética odontológica. Editorial interamericana, Buenos Aires . Argentina.
6. - Fischer, J. (1991). Prótesis parcial removible desde el punto de vista de la estética, en: Scharer, P., Rinn, L., Kopp, F. Principios estéticos en odontología restauradora. Editorial Doyma. Barcelona.España.
7. - Sykora, O. (1994). Esthetic considerations in the construction of a removable partial denture. Quintessence Int. 25 : 757-62.
8. - Belles, D. (1997). The Twin-flex clasp: an esthetic alternative. J. Prosthet Dent. 77: 450-2.
9. - Smith, B. (1979). Factores estéticos en las prótesis parciales removibles. Clin. Odont. Nort. 1 : 53-63.
10. - Sánchez, AE (1996). Prótesis parcial removible con eje rotacional de inserción. Acta Odont. Venez. 34 : 18-27.
11. - McGivney, G., Castleberry, D. (1992). McCracken prótesis parcial removible. 8ª ed. Editorial Panamericana. Buenos Aires, Argentina.
12. - Hansen, C., Geoffrey, W., Yverson W. (1986). An esthetic removable partial denture retainer for the maxillary canine. J. Prosthet. Dent. 56 : 199-203.
13. - Bezzon, O., Mattos, M., Ribero, R. (1997). Surveying removable partial dentures: The importance of guiding planes and path of insertion for stability. J. Prosthet. Dent. 78 : 412-18.
14. - Santana-Penín, U., Mora, M. (1998). An esthetically attractive Twin-flex clasp for removible partial dentures. J. Prosthet. Dent. 80 : 367-70.
15. - Pardo-Mindan, S., Ruiz-Villandiego, J. (1993). A flexible lingual clasp as an esthetic alternative: a clinical report. J. Prosthet. Dent. 69 : 245-6.
16. - Regan, S., Rold, T. (1996). Practical, esthetic options for retention of removable partial dentures: A case report. Quintessence Int. 27 : 333-40.
17. - Wright, S. (1984). Use of spring loaded attachments for retention of removable partial dentures. J. Prosthet. Dent. 51 : 605-9.
18. - Sánchez, AE (1997). Consideraciones periodontales y biomecánicos en el diseño de retenedores directos de PPR a extensión distal. Tesis de Postgrado. Caracas; Facultad de Odontología; Universidad Central de Venezuela.
19. - Mallat, E. (1986). La prótesis parcial removible en la práctica diaria. Editorial Labor. Barcelona, ​​Spain.
20. - Zinner, I. (1987). Aditamentos de precisión. Clin. Odont. Nort. 3 : 529-50.
21. - Swepston, S. (1988). Prótesis parciales con ataches de precisión en: Rudd, K., Morrow, R., Rhoad, J. Procedimientos en el laboratorio dental, prótesis parcial removible. Editorial Salvat. Barcelona, ​​Spain.
22. - Zinner, I. (1985). Conexiones de semiprecisión bloqueantes. Clin. Odont. Nort. 1 : 85-101
23. - Zinner, I. (1985). Tipos no bloqueantes de conexiones de semiprecisión. Clin. Odont. Nort. 1 : 103-22.
24. - Wolfe, R. (1985). Conexiones extracoronarias. Clin. Odont. Nort. 1 : 195-209.
25. - Staubli, P. (1991). Attachments and implants. Reference manual. USA Attachments International Inc.
26. - Weintraub, G. (1987). Prótesis híbridas. Clin. Odont. Nort. 3 : 577-608.
27. - Castleberry, D. (1990). Filosofias y principios de las sobredentaduras parciales removibles. Clin. Odont. Nort. 4 : 547-550.
28. - Fenton, A. (1998). The decade of overdentures: 1970-1980. J. Prosthet. Dent. 79 : 31-6.
29. - Stewart, K., Rudd, K., Kuebker, W. (1993). Prostodoncia parcial removible. 2ª Ed. Editorial Actualidades Médico-Odontológicas Latinoamericana. Caracas, Venezuela.
30. - Mensor, M. (1988). Ataches para sobredentaduras, en: Rudd, K., Morrow, R., Rhoad, J. Procedimientos en el laboratorio dental, prótesis parcial removible. Editorial Salvat. Barcelona España.
31. - Engelhardt, P., Willms, H. (1995). Elementos telescópicos de unión en la dentición fuertemente reducida. Quintessence técnica (ed. esp.) 6 : 295-325.
32. - Mensor, M. (1990). Sobredentaduras parciales removibles con aditamentos mecánicos (de precisión). Clin. Odont. Nort. 4 : 629-641.
33. - Epstein, D., Epstein P. (1993/1994). Una comparación clínica de tres tipos de anclajes para sobredentadura. Compendio. 9 : 69-75.
34. - Gillins, B., Samant, A. (1990). Sobredentadura con imanes. Clin. Odont. Nort. 4: 643-669.
35. - Sánchez A., Troconis I., Morelly E. (1999). El ejercicio de la prótesis parcial removible en la práctica odontológica de Caracas, Venezuela. Acta. Odont. Venez. 37
36. - Curtis, D., Curtis, T., Wagnild, G., Finzen, F. (1992). Incidence of various classes of removable partial dentures. J. Prosthet. Dent. 67 : 664-7.
37. - Owall, B., Spiekerman, H. (1995). Removable partial denture production in Western Germany. Quintessence Int. 26: 621-7.






AESTHETIC CONSIDERATIONS IN THE DESIGN OF DIRECT RETAINERS removable partial denture aesthetic considerations denture design direct partial removable retainers