Palmeri Publishing Inc. is committed to providing a healthy, secure, and safe work environment as we closely monitor the COVID-19 Virus and we are closed from Wed. Mar 18.2020 till Wed. May 13.2020 Please note if you place any order for a Book or DVD during this period, we are not able to ship it.
Axial attachments in large mandibular complete dentures help make removable prostheses more comfortable for the patient. Designed to be fixed on the natural root, their longevity has often been unpredictable in the medium term due to root fractures, support root caps working loose, and the removable prostheses fracturing. The prognosis improved when osteointegrated implants were introduced.1 The 2002 McGill conference established that the current therapeutic standard for treatment using mandibular complete dentures is the implant supported removable prosthesis with two osteointegrated implants. The removable prosthesis must also respond to the usual factors affecting equilibrium with the support surface, have correctly modeled and adjusted edges, and no unstable or unbalanced guidances.
Abstract: Self-curing repair resins are generally used to repair broken dentures. Conventional repair resins used may generate different results. Although these resins offer cost effective options, regrettably the repaired dentures lose 40% to 60% of their transverse strength. Traditional repairs are completed outside of the mouth and are sent to the dental laboratory for repair.
This usually includes a lengthy process of model making and submersion in a pressure pot for curing. A new repair resin based on diacrylate can be processed in the mouth, thus saving considerable time for both patient and the dental health professional. To facilitate a superior repair juncture an adhesive primer is utilized for optimal bonding of the broken denture.
Key Words: denture fractures, repair resins, adhesive primer, diacrylate, polymethylmethacylate.
Most edentulous patients enjoy satisfactory function and aesthetics if provided with well made and well maintained complete dentures. When treatment planning for patients who are facing complete loss of their dentition it is in the patients’ interest to consider a simple, low technology solution first (complete denture) and to move into more complex treatment options (implants) if the first proves unsuitable. Patients may seek a more complex treatment approach because:
• They may object to palatal coverage or it causes gagging
• Inadequate retention for that individual
• Psychological objection to a removable prosthesis
• A perception that a more complex and more expensive treatment option will be superior
Implant prosthetic options for the edentulous maxilla are infinite, but three useful approaches in practice are:
1. Porcelain fused to metal (PFM)fixed complete denture (FCD)- (segmentalised bridges) into fixed partial dentures (FPD’s)
To obtain unilateral chewing stability: forget about balanced occlusion, it doesn’t work, but: Perfect equilibrated occlusion is essential during parafunctional mandibular movements to prevent unbalanced loads on the supporting alveolar ridges.
1. Food is almost always chewed on one side only (Hiltebrandt, 1933/35)1.
2. During mastication the teeth of the denture wearer only finally come into con-tact when the food load has become softened (A. Gerber, 1946)2, 3.
3. Therefore the bi-lateral equilibrium is ineffective for chewing stability.
4. For the unilateral chewing stability of dentures, immobility is the key.
5. Parafunctional contacts are occurring both day and night. In order to distribute these forces evenly, correct centric and equilibrating contacts are necessary.
The study from Suguru Kimoto et al.4 showed greater satisfaction of the patient wearing dentures with a lingualised occlusion concept. The article “The effect of occlusal contact localisation on the stress distribution in complete maxillary denture”5 describes the connections which contribute to broken dentures. According to this study, it is the form of occlusion and the positioning of the teeth in relation to the alveolar ridge which leads to an unstable load and to broken dentures.
Planning and designing implant borne fixed partial dentures (FPDs) of various sizes, and varying degree of complication, are common tasks in the modern dental laboratory. While this relatively new treatment choice has improved the lives of literally millions of patients around the world, certain complications and challenges have unfortunately also arisen. Bone and tissue loss, prosthetically incorrect fixture placement together with a high smile line, peri-implantitis, as well as certain aesthetic and phonetic demands, are probably the most common features contributing to complication. . In many cases these deficiencies can only be addressed by means of restorative dentistry. These technical and clinical challenges often translate directly into certain functional as well aesthetic issues. An adequate restoration needs to achieve a satisfactory compromise between the aesthetic demands of our patients, as well as practical and functional aspects, such as access for oral hygiene, which in a study by Serino and Strome (1) was found to be the major contributing factor to peri-implantitis. No matter how large or complex the case might be, my standard approach to case planning and design for any implant PFM treatment is always the same.
Lingualized Occlusion is a setup technique developed to enhance denture stability for patients with severe alveolar bone resorption resulting in little or no ridge, or resulting in a discrepancy between the size of the narrowing and receding upper ridge compared with the widening and receding lower jaw (Fig. 1). This setup technique is also indicated for patients with implant-supported overdentures to eliminate lateral forces that can rock abutments loose over time. Additionally, lingualized occlusion is appropriate for free-end attachment cases to reduce stress on distal extension, or for intra-coronal attachments to avoid breakage.
For denture setups in a conventional occlusal scheme, both the buccal and lingual cusps of the upper and lower denture come into contact on the working side during lateral jaw movement. This achieves balance and distributes the bite force over the widest area of the jaw. By contrast, in a lingualized occlusion scheme, the objective is the elimination of buccal cusp contacts in order to alleviate lateral stresses or lateral dislodging forces. In lingualized occlusion, the lingual cusps of the upper posteriors make contact in centric relation in the central fossae of the lower posteriors. The buccal cusps are out of contact; however, the lingual cusps are in contact in centric, working and balancing movements. For this reason, all the stresses created during working and balancing motions are of a downward nature, thus creating stability.(Figs. 2,3)
Removable prosthetics on edentulous upper and lower jaws will inevitably result in bone atrophy; consequently the prosthesis will lose its grip. Depending on the cause of the tooth loss,for example, advanced chronicle Peritonitis, it is possible that an additional absorption occurs with a distinctive horizontal atrophy pattern in the crestal area. This scenario makes it more difficult to place four interforaminal implants correctly with consideration to the tooth axis. Dr. Martin Keweloh, and Axel Mühlhäuser, DT, will introduce such a case and its prosthetic approach.
Many older people would like tooth replacements that match their age. Using an all-ceramic fixed upper denture as an example, the following case report indicates some of the contouring and shade factors that must be kept in mind by the dental technician when working on customized age-matched restorations.
Keeping patients comfortable with dentures that are resting on less than ideal ridges is becoming increasingly difficult. Severe atrophic ridges and thin mucous membrane areas are a daily challenge for denturists because patients expect comfort from their dentures. Dental implants are the optimum treatment option, however many patients choose not to have implants for a number of reasons. In such cases an alternative must be found. Although soft lining material is not in any way a substitute for dental implants, it is an attempt to keep the patient as comfortable as possible.
Soft liners have had a long standing role in the dental profession in varying applications. I have used a variety of soft liners over the years and have had challenges and limitations in their use. I gave up in frustration, shying away from using them as temporary or long term laboratory technique because ultimately they posed problems for me and my patients, despite the promises made by the manufacturer.
An overcasting is a metal frame that fits intimately over a milled implant bar (0 degree or 2 degree milled) that inconjunction with a semi-precision attachment will retain, strengthen and provide over all stability for an implant supported overdenture. A cost effective alternative to Spark Erosion (electrical discharge machining method of fabricating precise overcastings), this type of modified removable partial denture frame can be fabricated in chrome-cobalt or non-precious alloys and produced at a fraction of the cost. Overcastings will also provide customized metal housings for attachment components. They can be fabricated in one of two methods (refractory and resin-overlay) which can be easily carried out by any dental lab that casts on a regular basis.
The indirect or refractory method (Seq. 2) follows the same steps used in the fabrication of a removable partial denture frame. The second method is the direct or resin-overlay method (Seq. 1) and it involves applying Pikuplast modeling resin (Bredent) directly over a milled and blocked out implant bar frame and its corresponding attachment components. Once the Pikuplast resin sets, mechanical retentive elements such as mesh wax turned flat side up (Fig. 2-5) or retentive crystals or beads can be added. The pattern can now be lifted off of the bar, sprued, invested and cast in a traditional crown and bridge style. Due to the accuracy and exceptional handling properties of Pikuplast; the resin-overlay method is the most efficient and the least time consuming of the two methods.
Patients may present with worn or broken overdentures that were retained by “O” ring superstructures requiring fabrication of a new overdenture. This may present a challenge when the “O” ring heads are an integral part of the implant as is seen with subperiosteal implants or it is not practical to remove the supracrestal portion of the overdenture to construct the new denture.
This article will address a technique to allow capture of the “O” ring heads and provide a master cast for fabrication of a completed overdenture.
Typically, “O” rings and their corresponding heads are available in limited diameters. It is important to identify this diameter so that an accurate master cast can be fabricated that replicates the heads intraorally. A caliper may be used intraorally to measure the “O” ring head. It is important to measure the head at its widest diameter to get an accurate size.
If a intervening bar is present between the heads this is blocked out with wax or other material to prevent the impression material from flowing under the bar and locking the impression intraorally. It is recommended that a medium viscosity impression material be used to create a master cast. Impression material is injected around the heads intraorally then an impression tray filled with additional material is seated and allowed to set. Upon setting the impression is removed and plastic analogs corresponding to the size of the “O” rings heads are snapped into the impression and a master cast is poured. Wax is placed over the analog heads to create a spacer between the record base and the analogs. A record base can then be fabricated to overlay the analog heads and a wax rim is attached. The record base/wax rim is returned to the dentist for adjustment for proper vertical dimension of occlusion and interarch records are taken. The casts are mounted at the laboratory and teeth are set in wax to be returned for intraoral try in.