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Various types of attachments have been used during overdenture fabrication; however, no single attachment is perfect for every case. Irrespective of the attachment used, it is important to maintain parallelism between the attachments for ease of insertion and removal, functional efficiency, and durability of the prosthesis. It is challenging to obtain parallelism between attachments when the abutments are divergent, or multiple abutments are engaged. A simplified technique to fabricate cast overdenture attachments using indigenously made parallelometer has been described. This technique eliminates the need of making full-arch impressions and models and surveying the attachments before casting. With this technique, there is a reduction in the duration and cost of treatment, without any compromise in quality of the prosthesis.

Objectives: The finishing of the gingival floor and its margins is regarded to be necessary in Class II cavities, so the aim of this research was to evaluate 4 finishing systems for the cervical margins of Class II cavities, with regard to surface roughness and waviness. Methods: Eighty Class II cavities were prepared in 20 intact molars by a single operator, using a diamond-coated bur (granulometry 80 μm) mounted on a parallelometer, under magnification (5x, Zeiss) in order to reduce variability. In every tooth, 4 different finishing methods were randomly applied: A: carbide bur; B: straight hand chisel; C: diamond-coated bur 60 μm; and D: diamond-coated sonic instrument. After that, the gingival floor of each cavity was analysed with an optical profilometer. Mean surface roughness (Ra) and mean surface waviness (Wa) were evaluated with an optical device. Results were analysed with ANOVA after ln-transformation of data. One- and two-way ANOVA was applied. Results: There was no statistically signi...

Purpose: The aim of this study was to evaluate the marginal discrepancy (MD) and internal discrepancy (ID) of ceramic crowns manufactured by a CAD/CAM system, having different finish lines. The hypotheses tested were that the finish line type would not influence the MD or ID of the crowns, and ID would not change in different regions. Materials and Methods: Three aluminum master dies (height: 5.5 mm, O: 7.5 mm, conicity: 6°) with different finish lines (TC: tilted chamfer; LC: large chamfer; RS: rounded shoulder) were manufactured. Ten impressions were made from each master die using a modified parallelometer. Impressions were poured in type IV dental stone, and 30 ceramic crowns (IPS Empress CAD, Ivoclar) were subsequently milled. The crowns were fixed on their respective metallic die using a metallic fixation device. The distance between the external edges of the crown to the edge of the cervical preparation was performed at 50 points on the respective metallic die (MD analysis). With the replica technique, the ID values of each crown were further evaluated at 12 points equidistant to each other in three regions: radius (R), axial (A), and occlusal (Occl). The measurements were performed using an optical microscope (250×). The data (μm) were analyzed using ANOVA and Tukey′s test (5%). Results: The RS group (28.24 ± 11.42 μm) showed significantly lower MD values (p= 0.001) than those of TC (99.92 ± 18.32 μm) and LC (64.71 ± 25.64 μm) groups, both of which also differed statistically from one another. The ID results demonstrated significantly lower values in the LC group (183.01 ± 62.82 μm) (p= 0.0014) than those of TC (216.26 ± 83.23 μm) and RS (219.12 ± 87.24 μm) groups. ID results of TC and RS were not significantly different. Additionally, the ID results showed significant differences among the regions (p= 0.0001). The null hypotheses were rejected. Conclusion: The RS finish line produced MD values significantly lower than tilted and large chamfer, but large chamfer presented the lowest internal discrepancy values. Independent of the finish line type, internal discrepancy was the lowest in the axial region followed by radius and occlusal regions.

Objectives: The aim of this experimental study was to identify relevant surgical parameters influencing the mesiodistal angular deviation of dental implants. Material and methods: Pilot drillings of 2 mm diameter were performed in bovine ribs with a parallelometer. The subsequent preparation of the implant socket was performed freehand. Utilizing six different implant systems, at least 80 drillings per system of different diameters were performed. The pilot drillings were marked with 2 mm steel pins and cephalometric radiographs were taken. The mesiodistal angle between the longitudinal implant axis and the marked pilot drillings was measured and evaluated by a blinded investigator. To evaluate the influence of the surgeons' experience, their drillings were compared with those of a group of unexperienced surgeons. Additionally, the influence of drilling speed and size of bur steps on drilling accuracy were evaluated. Results: The difference between the lowest value of 0.91° of mesiodistal angular deviation found for 3i® implants and the highest of 1.36° for Ankylos® implants was of low statistical significance (P=0.065). Drillings of experienced surgeons showed less deviation compared with those of a beginners group (P

This study evaluated the tension force of cast frameworks made by the technique of framework cemented on prepared abutments using two different resin cements. Forty multi-unit abutment analogs were individually fixed with chemically cured acrylic resin inside PVC cylinders using a parallelometer. Brass cylindrical abutments were tightened to the multi-unit abutments to be used as spacers and then castable UCLA abutments were positioned above. These abutments were cast with Ni-Cr and then divided into 4 groups (n=10): cemented with RelyX U100(r); cemented with RelyX U100(r) and simulation of acrylic resin polymerization process; cemented with Multilink(r); and cemented with Multilink(r) and simulation of acrylic resin polymerization process. Abutments were cemented according to manufacturers' instructions. In a universal testing machine, tensile strength was applied in the direction of the long axis of the abutments at 1 mm/min crosshead speed until displacement of the luted abutments was obtained. The values of maximum tensile force (N) required for the displacement of the luted abutments were tabulated and analyzed statistically by one-way ANOVA with a 95% confidence level. No statistically significant difference was found among the groups (p>0.05). There was an increase in mean tension force when the specimens were subjected to the simulation of acrylic resin polymerization process, but the results did not differ statistically. Both resin cements presented positive results as regards the retention of luted abutments on their respective multi-unit abutments. Both materials may be indicated for the technique of framework cemented on prepared abutments when professionals pursuit better adaptation of implant-supported frameworks. Este estudo avaliou a força de tração de infraestruturas fundidas confeccionadas pela técnica da infraestrutura cimentada sobre pilares preparados utilizando dois diferentes cimentos resinosos. Quarenta análogos de pilares multi-unit foram individualmente fixados com resina acrílica quimicamente ativada em cilindros de PVC utilizando um delineador. Pilares cilíndricos foram torqueados aos pilares multi-unit para serem usados como espaçadores e, então, pilares calcináveis UCLA foram posicionados sobre eles. Estes pilares foram fundidos em liga de Ni-Cr e divididos em 4 grupos (n=10): cimentados com RelyX U100(r); cimentados com RelyX U100(r) e simulação do processo de polimerização da resina acrílica; cimentados com Multilink(r); e cimentados com Multilink(r) e simulação do processo de polimerização da resina acrílica. Os pilares foram cimentados de acordo com as recomendações dos fabricantes. Em máquina universal de ensaio, a resistência à tração foi aplicada na direção do longo eixo dos pilares a uma velocidade de 1 mm/min até o deslocamento do pilar cimentado ser obtido. Os valores da tração máxima (N) necessária para o deslocamento dos pilares cimentados foram tabulados e analisados estatisticamente pela ANOVA de 1 fator com 95% de nível de confiança. Diferença estatisticamente significativa não foi encontrada entre os grupos (p>0,05). Houve um aumento na força média de tração quando os espécimes foram submetidos à simulação de processo de polimerização da resina acrílica, mas os resultados não diferiram estatisticamente. Ambos os cimentos resinosos apresentaram resultados positivos no que diz respeito à retenção dos pilares cimentados em seus respectivos pilares multi-unit. Ambos os materiais podem ser indicados para a técnica da infraestrutura cimentada sobre pilares preparados quando os profissionais buscam melhor adaptação de infraestruturas de próteses implanto-suportadas.

This study evaluated the strength required to remove glass-fiber and metallic cast posts with different lengths. Sixty endodontically treated canines were included and their roots were embedded in acrylic resin after discarding the crowns. Samples were randomly assigned to 3 groups according to the post length (n = 20): I- 6 mm, II - 8 mm and III- 10 mm. Each group was divided into 2 subgroups based on the post material (n = 10): A- glass fiber or B- metallic cast. Post-space was prepared with Fibrekor Post Kit attached to a parallelometer. In subgroup A, prefabricated glass fiber posts from Fibrekor Post Kit were utilized. In metallic post group (subgroup B), an impression of post space was obtained, followed by casting. All posts were luted with Panavia F cement. A universal testing machine determined the force required to dislodge each post. ANOVA analysis indicated significant differences (P0.01) among post length. Tukey test showed that posts with 10 mm-length showed higher resistance on removal than posts with 6 mm-length. Posts with 8 mm-length did not exhibit difference when compared to 6 and 10 mm posts. No significant differences (P0.05) were observed between the tested post materials. It was concluded that the type of post did not influence the removal resistance and that posts with 10 mm-length required greater force to be dislodged.

The dental surveyor is an indispensable instrument capable of performing a number of prosthodontic procedures. Surprisingly, the technique of surveying casts as part of the treatment planning procedure did not emerge until early in the twentieth century. This article reviews the origins and early use of the dental surveyor. It includes features common to all surveyors as well as the principal uses of these instruments.

summary The purpose of this in vitro study was to evaluate crown retention after using different sealing systems on prepared dentine. Ca(OH)2 suspension was used in comparison with three adhesive bonding systems (Gluma Desensitizer, Optibond FL, Prompt L-Pop). Extracted human premolars were uniformly prepared with the use of a special parallelometer (11° taper, 4 mm axial length). Groups of 20 teeth each were treated with each sealing system. Then crowns were fabricated and temporarily cemented twice. Finally the abutments were cleaned and the crowns were cemented with a glass–ionomer cement Ketac-Cem. Subgroups of 10 crowns were removed with a universal testing machine following storage in distilled water either for 3 days or for 150 days. Prior to dislodging, the crowns of both groups were subjected to chewing simulation. The mean dislodgement stresses in MPa were between 4ḃ9 and 6ḃ9. A range test of Student–Newmann–Keuls revealed significant differences between Ca(OH)2 and Optibond FL (P

A simple mechanical device is introduced, the parallelometer, that can be used to measure curvatures of surfaces. The device can be used as a practical illustration of parallel transport of a vector and to study Berry phase shift when it is carried along a loop on the surface. Its connection to the Foucault pendulum is discussed. The experimental results can be successfully compared with the theoretical expectations. The experiment is inexpensive and conceptually easy to perform and understand for a beginner.

Statement of problem. A precise preparation is required to develop resistance form resulting in mechanical stability of the framework for resin-bonded prostheses (RBPs). Purpose. The effects of 4 methods of tooth preparation (freehand, guiding pin, extraoral parallelometer, and intraoral parallelometer) on the deviation of proximal grooves from a preestablished path of insertion (guide planes) were investigated under clinical conditions. Material and methods. Tooth preparation of proximal grooves was performed by 32 dentists on resin substitutes of posterior segments intraorally with a single test patient. A Latin-square randomized cross-over design was selected as the experimental design. Results. The significant least angular deviation of proximal grooves from path of insertion was achieved with an intraoral parallelometer (mean ± SD 3.15 ± 1.67 degrees). Compared with freehand tooth preparations (4.37 ± 2.11 degrees), neither use of a guiding pin (4.10 ± 1.62 degrees) nor an extraoral parallelometer (5.06 ± 2.33 degrees) improved the results. Conclusion. Divergence of guiding grooves from path of insertion was reduced with the use of an intra-oral parallelometer. This should improve mechanical stability of posterior RBPs. (J Prosthet Dent 1999;82:398-409.)

A perda de dentes além de afectar a mastigação e a estética, altera também o equilíbrio do sistema estomatognático, observando-se de imediato alterações na posição dos dentes adjacentes e dos dentes oponentes. Torna-se, portanto, imprescindível para a reposição da saúde oral do paciente a reabilitação com recurso a próteses fixas ou removíveis. No que diz respeito às próteses parciais removíveis (PPR´s) estas visam a substituição dos dentes perdidos, sendo facilmente removidas e inseridas pelo paciente, sem qualquer intervenção do médico dentista e, apoiam-se directamente na mucosa e nos dentes. Enquanto as PPR´s acrílicas são suportadas pela mucosa, mediante uma ampla área de contacto, as próteses esqueléticas são suportadas pelos dentes pilares através da colocação de retentores. No caso específico das PPR´s, é fundamental que o profissional de saúde tenha em consideração a importância do planeamento correcto e adequado da reabilitação oral. Para isso, pode e deve utilizar o paralelómetro, determinando assim correctamente a localização dos planos-guia, dos apoios e retentores necessários. Guiando-se por estes princípios fundamentais, qualquer reabilitação com recurso às PPR´s pode ser bem sucedida quer a nível estético quer a nível funcional. The loss of teeth as well as affect chewing and aesthetics, also alter the balance of the stomatognathic system, observing immediate changes in the position of adjacent teeth and opposing teeth. Thus, it becomes essential for the restoration of the patient's oral health rehabilitation using fixed or removable prostheses. The removable partial dentures (RPD's) aimed at replacing lost teeth, but not all teeth. These prostheses are easily removed and inserted by the patient, without any intervention by the dentist and supported directly on the teeth and mucous membrane. While RPD's acrylics are supported by the mucous membrane by a wide contact area, the skeletal prostheses are supported by the abutment teeth by placing hooks. In the specific case of RPD's, it is essential that health professionals take into account the importance of proper planning and appropriate rehabilitation. To do so, he can and should use the parallelometer, thus determining the correct location plans guide, support and the necessary hooks. Guided by these principles, any rehabilitation with use of RPD´s can be successful at either aesthetic or functional level.

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In the last decade, several systems for computer-planned implantology have been reported. Among them is a system that uses software and a three-dimensional parallelometer able to transfer the implant position from the virtual project to the master model. To verify the effectiveness of this system, a retrospective comparative study has been planned.A series of 300 implants were analyzed. Sixty-six were inserted with computer planning. Several variables related to patient, anatomic site, implant, and surgery were investigated. Implants' failure and peri-implant bone resorption were considered as predictors of clinical outcome. Kaplan-Meier method and Cox regression analysis were then performed to detect those variables statistically associated with the clinical outcome.Implant length and diameter ranged from 10 to 16 mm and from 3.75 to 6.0 mm, respectively. Implants were inserted to replace 66 incisors, 39 canines, 116 premolars, and 79 molars. Mean follow-up was 14 months. Nine implants were lost (survival rate, 97%), but no differences were detected among the studied variables. On the contrary, lower crestal bone resorption was detected for implants inserted in healed bone and in anterior jaws.Computer-planned and cast model-transferred implantology give good clinical results in survival and success rate. It is a useful technology that should be used in most difficult cases such as totally edentulous patients and reduced crestal bone volume.

Statement of problem There are insufficient data on the accuracy of resin indexing materials for the assembly of implant prostheses in vivo. Material and methods This in vitro study assessed the fit of an implant framework with the use of 2 common acrylic resins. Purpose A standardized type IV gold alloy cast framework with 3 stainless steel implant replicas secured to 3 premachined gold cylinders placed 200 mm apart using a parallelometer was fabricated on a flat type IV stone model. Wax was placed around the center of each bar section, and a silicone matrix was fabricated to enable the same quantity of material to be used for each assembly. Each bar was sectioned at the center of the matrix, and indices (n=20) were fabricated from Duralay and GC Pattern acrylic resins. The materials were allowed to polymerize for 15 minutes before the assemblies were removed from the model. Frameworks were visually assessed for fit after an additional 15 minutes, after 2 hours, and after 24 hours, using the Sheffield 1-screw test. Observational outcomes are presented indicating visually perceived fit relative to the type of indexing resin. Results Both indexing materials were judged to be visually accurate at the 15-minute time interval only. Conclusion Within the limitations of this in vitro study, both resin-indexed implant assemblies were judged visually accurate for fit 15 minutes after polymerization but not at subsequent test intervals.

16. Courtade GL. Methods for splinting the lower anterior teeth. Dent Clin North Am 1970;14:3-17. Jones RB. Ixnra-coronal pins. Br Dent J 1969;127:580-2. Pameijer CH: Stallard RE. Effect of self-threading pins. J Am Dent Assoc 1072;85:895-9. Caputo AA, Standlee JP, Collard EW. The mechanism of load transfer by retentive pins. J PROSTHET DENT 1973;29:442-9. Collard EW, Caputo AA, Standlee JP. Rationale for pin retained amalgam restorations. Dent Clin North Am 1970;14:4351. Dilts WE, Welk DA, Laswell HR. Crazing of tooth structure associated with placement of pins for amalgam restorations. J Am Dent Assoc 1970;81:387-91. Markley MR. Pin retained and pin-reinforced amalgam. J Am Dent Assoc 1966;73:1295-1300. Vitsentzos SI. Extraoral parallelometer [Ph.D. thesis]. Thessalonki, Greece: School of Dentistry, University of Thessaloniki, 1979;62-5. Going RE. Pin retained amalgam. J Am Dent Assoc 1966;73:619-24. 17. Goldstein PM. Retention pins are friction locked without use of cement. J Am Dent Assoc 1966;73:1103-6. 18. Courtade GL. Pin pointers. III. Self-threading pins. J PROSTHET DENT 1968;20:335-8. 19. Timmermans JJ, Courtade GL. Non-parallel threaded pin retention of fixed prosthesis. J PROSTHET DENT 1968;19:38192. 20. Moffa JP, Going RE, Gettleman L. Silver pins: their influence on the strength and adaptation of amalgam. J PROSTHET DENT 1972;28:491-9. 21. Garansson P, Embrell A. Parallel pins in gold restorations. Int Co11 Dent 1970;3:101-4.

A parallelometer which can be used either intraorally or extraorally has been described. The parallelometer can be used with any type of handpiece, and any bur or disc can be controlled with it. It can parallel any number of abutment preparations regardless of the technique being used.

This report presents a simple, effective and inexpensive paralleling device for intraoral use.

A new parallelometer and a technique for its use have been described. This precision instrument is rigid, and has proved to be very accurate. No play in the instrument is allowed, and parts that wear out are easily replaced. It is used when preparing teeth for pinledges, inlays; for making grooves and ☐es for 3/4 crowns; and to check the alignment of multiple preparations. The instrument requires the use of special drills and stones. Paramax-drills are used for making the postholes, slightly conical fissure-burs, and diamond stones with the Paramax grib, and when preparing teeth for three-quarter crowns and full veneer crowns.