Fixed-fixed Bridge Research Articles

Different extra-coronal restoration options of hemisected teeth on structurally compromised mandibular molar: Report of two cases

Structurally compromised teeth tend to be extracted due to its their poor prognosis, however, hemisection may serve as an alternative option in selected cases. This case report is aimed to discuss two cases of hemisected mandibular molars with two different approaches for post-hemisection restoration. Case 1 presents with terminal tooth 37 diagnosed with a cracked tooth involving severe bone loss on the mesial root. The tooth was hemisected and restored with a mesially cantilevered full ceramic crown. Case 2 presents with root caries on an endodontically treated tooth 46 on a patient with bruxism, with an inadequate ferrule on the distal segment. The tooth was hemisected utilizing the socket preservation technique, and the tooth was restored with a conventional fixed-fixed bridge with a second abutment on tooth 47.

Effect of Different Type of Provisional Restorative Material on Micromovement of Immediate loading Implant

Aims. This in vitro study was to evaluate the effect of three type provisional restorative material on micromovement of immediate loading implant. Methods. Thirty samples of provisional bridges were fabricated using three different restorative materials A- Resinous CAD/ CAM. B- Dual cure composite .C- Conventional heat cure resin, fixed-fixed bridge cemented over implant by zinc oxide eugenol free based temporally cement. All samples were mounted in a computer-controlled materials testing machine with a loaded up to50N ,100N,150N,200N and data were recorded using computer software. Vertical displacement was measurement by using the image analysis software. Results. It was found that heat cure acrylic resin group recorded statistically significant highest (p<0.05), µ -movement mean value (75.70±7.615 µm) followed by dual cure composite group (53.15±5.330 µm). While, CAD/CAM resin group recorded statistically significant (p<0.05) lowest µ -movement mean value (39.66±3.325 µm) as indicated by ANOVA test followed by pair –wise Tuke's tests. Conclusion. Ceramill Temp (acrylic resin) implant supported bridges showed the lowest vertical micromovement compared to composite resin and heat cure acrylic resin provisional restorations.

REHABILITATION OF MASTICATION AND LACK OF SPACE TREATMENT IN NARROW EDENTULOUS WITH FIXED-FIXED BRIDGE

Background: Loss of posterior teeth can lead to disharmony in the curvature of the jaw. Antagonistic teeth and surrounding teeth will migrate to the edentulous causing reduced mastication function and TMJ disturbance. Several cases of narrow edentulous occurred due to tooth shifting caused by edentulous that was left empty for a long period. Creating a fixed-fixed bridge is aimed to restore the aesthetics, function, and comfort for patients which caused by the missing teeth. Fixed-fixed bridge consist of a retainer that function as a support to the abutment; a pontic that function to replace the missing tooth; and a connector that function to connect the pontic and the retainer. A narrow space for pontics can disrupt the aesthetic and functional aspects. Case Report: A 24 year-old male patient was referred to Prosthodontic Clinic, Gusti Hasan Aman Dental Hospital with a complain of pain on the jaw joint and missing of left lower molar for about 5 years. Patient always masticate on one side after the left lower molar was missing. Extraoral examination found the patient to be in good condition, no enlargement of major salivary glands, the vital signs were good, but upon TMJ examination there was clicking sounds on the left side. Intraoral examination showed space narrowing resulted from mesial and distal drifting of 37 and 35 but not significant, therefore it was still possible to perform rehabilitation using fixed-fixed bridge with abutments on 37 and 35 with modification of pontic shape for 36 to resemble a premolar tooth with occlusal surface resembling a molar tooth. Treatment planning for fixed prosthetic using fixed-fixed bridge with porcelain fused to metal material on 35, 36, and 37 with ridge lap pontic type modification Conclusions: Treatment was successful to provide enough space for the pontic by modification of the shape and the size of the pontic. Keywords: Fixed-fixed bridge. lack of space, mastication.

Biomechanical Analysis of the Zirconia and Graphene-based CAD-CAM Dental Bridges at Different Pontic Length: A Finite Element Analysis

Introduction: During masticatory loading, dental bridges are subjected to various forces that might generate deflections in the bridge framework. For this reason, designing long-span bridges require great care about flexions that happen during the function. This can be compensated by increasing occluso-gingival height, using rigid materials and enhancing resistance to deflection by modifying the abutments’ preparations. The current study hypothesied that the stress, deflection, strain and deformation of the fixed partial dentures are guided by the three-dimensional configurations of the pontic areas, and all other parameters could be mutually changed with different influence on the overall outcome. Aim: The study aimed to evaluate the difference in the amount of stress, deflection, strain and deformation on using different materials and configurations in the pontic and connector area of the dental bridge using the 3D Finite Element Analysis (FEA). Materials and Methods: An invitro virtual biomechanical analysis using 3D FEA method was conducted. 3D models were created from the Cone Beam Computed Tomography (CBCT) of a dentulous patient and two materials were selected for this study, Zirconia and enhanced graphene-based polymer. The study models were assembled into four groups as the following: Group I: 3-unit Zirconia fixed-fixed bridge; Group II: 3-unit Graphene fixed-fixed bridge; Group III: 4-unit Zirconia fixed-fixed bridge; Group IV: 4-unit Graphene fixed-fixed bridge. Using FEA software a 600 N load was applied and the resultant normal stress, deflection, maximum equivalent strain and total deformation data were monitored, collected and interpreted. Results: The findings of the current study showed higher values of normal stress, deflection, equivalent elastic strain and total deformation in Graphene-based bridges (group II and IV) than the Zirconia-based bridges (group I and III). It should also be mentioned that normal stress, deflection, equivalent elastic strain, and total deformation showed higher values in the three-unit bridge (group I and II) than their corresponding 4-unit bridge groups (group III and IV). Conclusion: This biomechanical analysis confirmed that the stress concentration and deflection of the fixed bridge are influenced by material characteristics. However, configuration of the pontic area could influence the studied mechanical parameters regardless the length of the dental bridge.

Posterior Maxillary Prosthetic Treatment with Molar Hemisection – A case report

Background: Hemisection is an alternative treatment option for maintaining tooth with multiple root that indicated for extraction. Purpose: To reported tooth with multiple root indicated by extraction to be used as a fixed-fixed bridge abutment by extracting the infected root and maintain the healthy one. Case: A 53-year-old woman with caries in upper 1st molar teeth in mesiobuccally root that can’t be maintained. Patients refuse the teeth to be extracted. Case Management: Hemisection treatment was performed on 26 mesiobuccal root, with the addition of bone graft. After the healing process, fixed-fixed bridges were made on 25, 26, 27, 28, with PFM on 25, 26, 27 and full cast crowns on 28 as the material. Discussion: Hemisection as a conservative treatment, can be an option for multiple root teeth that has been indicated for extraction but still have root that can be maintained. Conclusion: Teeth performed by hemisection treatments can be used as abutments with attention to the selection of patients to achieve long-term success.

Prosthetic rehabilitation using adhesive bridge and fixed-fixed bridge on the maxilla and telescopic crown overdenture on mandible

Prosthetic rehabilitation is the rehabilitation process of masticatory and esthetics function for patients missing teeth and alveolar bone by means of manufacture and installation of dentures. The prosthetic rehabilitation commonly used include denture adhesive bridge, fixed-fixed bridge, as well as telescopic overdenture. Adhesive bridge is bridge denture consisting of single pontic and two retainer wings attached to the abutment using cement or resin. Fixed-fixed bridge is a bridge denture with rigid connectors on both ends of the pontics, whereas the telescopic crown Overdenture is a removable denture that uses linked precision on the original tooth in the form of primary coping on abutment and secondary coping on the denture. To expose the procedures of prosthetic rehabilitation using adhesive bridge and fixed-fixed bridge on the maxilla and telescopic crown Overdenture on mandible. Male patients aged 32 years came with complaints of difficulty to chew food because he had lost some teeth behind. In the maxilla, teeth are lost in the region of 15 and 16 performed by making the fixed-fixed bridge with abutment teeth 14 and 17. Loss of teeth in the region of 26, performed the manufacture of adhesive bridge with a box preparation on the occlusal 25 and 27. In the mandible, tooth loss in the region of 36,37,46, and 47 performed manufacture of telescopic crown Overdenture with primer coping on the teeth 35.38, 45, and 48 and the secondary coping on a metal frame. Prosthetic rehabilitation especially in the case of loss of back teeth is very important because with the denture patients can chew properly and maintain the stomatognathic system.

The Dentist's Preferences on the Treatment of Missing Mandibular Incisors in Patients of Varying Ages

Introduction: When mandibular incisor teeth are absent or lost through disease, multiple options for replacement of these teeth are available. It is possible that a patient may receive varying treatment depending on the dentist’s preference for replacing missing mandibular incisors. Objective: The present study was aimed to determine the dentists’ preferences on treatment options to replace missing lower incisors in patients of varying ages. Materials and Methods: Fifty questionnaires together with clinical photographs, a radiograph, and study casts were given to dentists working in the Glasgow Dental Hospital and School and dentists working in a dental clinic in Libya. The questions included in the questionnaire were directed towards the assessment of dentists’ preferences on treatment options to restore missing lower incisors in patients of different ages. Results: For the 18 year old group the most commonly used treatment options were both the use of an adhesive bridge (36%) and a fixed-fixed bridge (36%) although the overall preferred treatment option was the use of a dental implant (68%). Generally, the respondents were in agreement to use the same treatment options for the patient of 40 years old as for the 18 year old (82%). More than half (56%) of the respondents were in agreement to use the same treatment options for the 60 year old patient as for the 18 year old. Conclusion: Within the limitations of this study it can be concluded that there was a difference between some of the dentists in the preferred treatment for the replacement of missing incisors in the clinical scenarios presented in this study.

Three years clinical outcome of hybrid fixed-fixed bridges

Subject: Hybrid fixed-fixed partial dentures present a conservative approach to the conventional type when a single tooth is replaced in the posterior region with certain indications. Aim: To evaluate various criteria’s like, post-operative sensitivity, gingival response, de-bonding of the retainer, secondary caries, retainer fracture resistance and patient satisfaction. Materials and methods: A total of 16 bridges were included in this clinical study. The patient selection, preparation techniques as well as bridges constructions were followed the current principles that recommended by the manufactures instructions and recent textbooks. Patients were clinically evaluated after 3 months from the final cementation. At 9, 18, and 36 months as follow-up period the patients were called by phone. Results: A good rate success was observed during the different evaluation periods. Gingival inflammation of one case was reported during 18 month evaluation, while two cases with de-bonding and post-operative sensitivity were recorded during the 36 month. 100% of patients were satisfied with these types of restorations. Conclusions: Hybrid fixed-fixed retained bridges appear to be an effective restoration in a single posterior missing tooth. Practitioners should consider its use as an alternative to bilateral full crown retained restorations.

Five-year clinical evaluation of zirconia-based bridges in patients in UK general dental practices

ObjectivesThis study reported the results at 5 years of fixed-fixed all-ceramic bridges, constructed in a yttria oxide stabilized tetragonal zirconium oxide polycrystal (Y-TZP) substructure, placed in adult patients in UK general dental practices. Materials and methodsFour UK general dental practitioners recruited patients who required fixed bridgework and, after obtaining informed written consent, appropriate clinical and radiographic assessments were completed. The teeth were prepared and bridges constructed in accordance with the manufacturer's instructions. Each bridge was reviewed annually within 3 months of the anniversary of its placement by a calibrated examiner, together with the clinician who had placed the restoration, using modified USPHS criteria. ResultsOf the 41 bridges originally placed, 33 bridges were examined at 5 years. All Y-TZP frameworks were intact and no bridge retainers had debonded. Eight chipping fractures in the veneering ceramic were noted over the 5-year period. In five cases the patients were unaware of these and these cases were polished. Of the remaining three cases, in one a repair was attempted but was unsuccessful, but the bridge remained in satisfactory service. However, in the case involving a chipping fracture of the mesial–incisal angle of a central incisor, it was considered that replacement of the bridge was necessary. Conclusion97% (n=32) of the 33 Lava Y-TZP fixed-fixed bridges, evaluated in patients attending UK general dental practices, were found to be performing satisfactorily. Clinical relevanceThe use of Y-TZP frameworks holds promise.

Microstrains Around Standard and Mini Implants Supporting Different Bridge Designs

The purpose of the study was to analyze microstrains around small- versus standard-diameter implants used in restoration of thin wiry ridge through different bridge designs. Additionally, influence of the site of occlusal vertical loading was evaluated using strain gauges. Two models simulating mandibular unilateral free-end saddle were fabricated. Two standard-size implants (3.75 × 13 mm) were inserted in one model in the position of the second premolar and first molar to support 2 3-unit cantilever bridges (NiCr alloy). On the other model, a standard implant and a mini implant (3.0 × 13 mm) were inserted in the position of the second premolar and second molar, respectively, to support 2 fixed-fixed 3-unit NiCr bridges. Four strain gauges were mounted buccally, lingually, mesially, and distally adjacent to each implant. The prostheses were temporarily cemented. A 300 N vertical load was applied on the middle of the horizontal runner bar connecting the prosthetic units and on the center of the pontics. Microstrains were recorded and analyzed. Cantilever bridges recorded higher microstrains than fixed-fixed bridges for both loading conditions. Yet, for both designs, loading on the horizontal runner bars, which apply an equal load on all bridge units simultaneously, resulted in significantly lower microstrain values than applying the load only on the pontics. Mini implant revealed greater strain values than standard implant supporting the same fixed partial denture. The best treatment option that produced the least microstrains was the fixed-fixed bridge with a mini implant as a terminal abutment. Mini implants induced higher microstrains than standard implants.

Performance of Laser Fluorescence for Detection of Occlusal Dentinal Caries Lesions in Permanent Molars: An in vivo Study with Total Validation of the Sample

The objective of this in vivo study was to evaluate the performance of a laser fluorescence device in detecting dentinal caries in noncavitated occlusal surfaces. The sample included 102 first and second permanent molars, selected according to the criteria of Ekstrand et al. [Caries Res 1997;31:224–231]: 46 not suspected of having dentinal caries (score: 0–2) and 56 under suspicion (score: 3–4). Once measured by laser fluorescence, all were validated by fissurotomy (gold standard). To avoid ethical questions, the 46 teeth (score: 0–2) used were to serve as abutments for a fixed-fixed bridge. Visual inspection performed well, showing a sensitivity and specificity of 0.93 and 0.88, respectively. Laser fluorescence had an area under the receiver operating characteristic curve of A_z = 0.85. The cutoff point with the highest sensitivity and specificity was 20, with a sensitivity and specificity of 0.89 and 0.75, respectively.

Fate of vital pulps beneath a metal‐ceramic crown or a bridge retainer

To investigate the incidence of and factors associated with pulpal necrosis in vital teeth restored with metal-ceramic crowns (CMCs) or crowned as part of a fixed-fixed bridge. Patients who had a CMC or bridge retainer (BR) placed on a tooth with no previous history of root canal treatment from 1981 to 1989 were retrieved from computer records. The collated patients were randomly selected and their clinical records examined. Those who satisfied the inclusion criteria were contacted and offered a review. After clinical examination, long-cone paralleling periapical radiographs were taken of the selected teeth, which were then assessed by two precalibrated operators to ascertain the pulpal status. Factors that might contribute to loss of pulp vitality and the tooth type were also recorded. The collected data were analysed statistically using the chi-square test and subject to Bonferroni adjustment where indicated. The numbers of preoperatively vital teeth in the CMC and BR groups were 122 and 77, and the mean observation periods were 169 +/- 25 (SD) and 187 +/- 23 months, respectively. In the CMC group, 19 failed cases (15.6%) were due to an endodontic reason; total number of failures was 34. In the BR group, 25 (32.5%) showed signs of pulpal necrosis; a significant association with maxillary anterior teeth was noted. The survival rates for pulp vitality were 84.4% (CMC) and 70.8% (BR) after 10 years, and 81.2% (SC) and 66.2% (BR) after 15 years. The difference between the two groups was significant. The survival of the vital pulp in teeth restored with a single-unit CMC was significantly higher than those serving as an abutment of a fixed-fixed bridge. Maxillary anterior teeth used as bridge abutments had a higher rate of pulpal necrosis than any other tooth types.

Electromechanical model of RF MEMS switches

With the recent rapid growth of Radio Frequency Micro-Electro-Mechanical Systems (RF MEMS) switches, there has developed an emergent requirement for more accurate theoretical models to predict their electromechanical behaviors. Many parameters exist in the analysis of the behavior of the switch, and it is inconvenient for further study. In this paper, an improved model is introduced, considering simultaneously axial stress, residual stress, and fringing-field effect of the fixed-fixed bridge structure. To avoid any unnecessary repetitive model tests and numerical simulation for RF MEMS switches, some dimensionless numbers are derived by making governing equation dimensionless. The electromechanical behavior of the fixed-fixed bridge structure of RF MEMS switches is totally determined by these dimensionless numbers.

Fixed Prosthodontic Replacement of Single Incisors in Three Dogs

Three dogs each received a three-unit fixed-fixed porcelain-veneer bridge for the replacement of traumatically-lost upper first or second incisor teeth. The bridges remained in place for a period ranging from 6-36 months, before becoming dislodged as a result of external trauma. It was concluded that this type of bridgework is technically feasible and may be justifiable.

合釘を装着した架工義歯支台歯の応力解析

Stress analysis of bridge abutment teeth having cemented dowels was conducted using a two-dimensional finite element method. The results obtained are as follows: 1. In fixed-fixed bridges, compressive stress was found concentrated within the dowel, on the mesial side of the dowel apex, and in the distocervical part of the crown. 2. In cantilever bridges, tensile stress was found concentrated in the disto-occlusal and mesiocervical parts of the crown, and along the mesial sides of the root and the dowel. Compressive stress was concentrated in the distocervical part of the crown, along the distal sides of the root and dowel, and on the mesial side of the dowel apex. 3. In comparison with fixed-fixed bridges, stresses were significantly greater in cantilever bridges in the abutment teeth, the dowel, and crown margins. 4. In both fixed and cantilever bridges, stresses increased in relation to the length of the span. The rate of increase was less, however, in fixed-fixed than cantilever bridges.