A comparative study of the cutting efficiency of diamond rotary instruments with different grit sizes with a low-speed electric handpiece against zirconia specimens.

STATEMENT OF PROBLEM: The use of zirconia in dentistry has increased. However, little attention has been given to the difficulty experienced by clinicians when cutting zirconia restorations intraorally. Evidence for which grit size and type of rotary instrument is best for cutting zirconia intraorally is lacking. PURPOSE: The purpose of this in vitro study was to identify the most efficient diamond rotary instrument grit size for cutting zirconia intraorally. MATERIAL AND METHODS: Efficiency was measured by comparing the cutting depth of each rotary instrument into zirconia, analyzing zirconia specimens for surface damage after cutting, and measuring instrument deterioration. Thirty zirconia specimens of the same measurements were used as test specimens and cut with 30 diamond rotary instruments with different grit sizes. An electric handpiece was used with constant force (1.7 N), speed (40 000 rpm), time (1 min), and water flow rate (25 mL/min) to produce comparative data. The mean cutting efficiency values were compared by analysis, and the median values were compared by the nonparametric Kruskal-Wallis test (α=.05). Each test was followed up with pair wise comparisons of the mean or median values if significance was indicated. RESULTS: The greatest cutting depth was achieved with a fine-grit instrument with a mean cutting depth of 5.79 mm compared with 4.54 mm for the coarse-grit instrument (P=.032). The greatest damage to zirconia was done by the coarse- and supercoarse-grit instruments (both 33%), with no substrate damage by the superfine-, fine-, and medium-grit instruments. The greatest instrument deterioration was found on the supercoarse rotary instruments (9.05%). With only 3 exceptions, the power calculations were all sufficient and above 83%. CONCLUSIONS: The fine grit rotary instrument (between 40 and 50 µm) was the most efficient, achieving the greatest cutting depth, with no detectable macroscopic damage to the zirconia and minimal instrument deterioration.

Comparison of excess cement around implant crown margins by using 3 extraoral cementation techniques.

STATEMENT OF PROBLEM: Extrusion of excess cement into the subgingival area around implant-supported crowns is associated with detrimental inflammatory response, but controlling this excess material remains a challenge. PURPOSE: The purpose of this in vitro study was to perform a comparative analysis of 3 extraoral cementation techniques to reduce excess extruded cementation material around implant-supported crowns. MATERIAL AND METHODS: Forty-four internal connection implant replicas were embedded in acrylic resin to form the experimental model. Cementable abutments were tightened onto the implants. Zirconia crowns were luted to each of the cementable abutments by using 1 of 4 techniques: control, pattern resin analog that was 3D-printed, fast-setting polyvinyl siloxane analog, and putty index analog. Extruded excess cement was collected at each luted crown and weighed. RESULTS: The mean residual weight of excess cement found in the pattern resin analog technique group was the least (0.087 mg), followed by the polyvinyl siloxane analog technique group (1.678 mg). The putty index analog technique group reported the least reduction of excess extruded cement (7.621 mg). All techniques produced substantially less extruded cement than the control (85.166 mg). In a 1-way analysis of variance, statistically significant differences (P<.001) were found among all the test techniques. Pairwise comparisons also found that all 3 test techniques were statistically different from each other. CONCLUSIONS: The pattern resin (3D-printed) analog technique produces the least amount of extruded excess cement at an implant-supported crown, limiting detrimental impact on peri-implant tissue health.

Immediate Implant Placement and Provisionalization Following Tumor-Resective Surgery in the Midfacial Region: A Case Series.

Surgical and prosthodontic restoration of the midfacial region following tumor resection has always posed a considerable challenge, as this area serves crucial functional and esthetic roles. Being diagnosed and subsequently treated for facial tumors can have an immense psychosocial impact on a patient, as the resulting defects are often disfiguring, and lead to an inability to masticate, swallow, and speak clearly. Provision of an immediate facial and dental prosthesis at the time of surgery can limit these side effects and help reduce mental duress on these patients and their families, as well as aid in the process of rehabilitation. Rapid prototyping (RP) and 3D printing, as this paper shows, assists presurgical planning of the tumor resection, as well as the manufacture of maxillofacial and dental prostheses. Often these defects are extensive, so prosthesis retention is aided by zygomatic implants placed at the time of surgical resection. When placed at this time, and prior to radiation therapy, these craniofacial implants have improved survival rates. Thus, this treatment modality can improve postoperative recovery considerably, while at the same time allowing for cleaning and monitoring of the resected site for tumor recurrence.

The Effects of the Refugee Crisis on Age Estimation Analysis over the Past 10 Years: A 16-Country Survey.

Dental age estimation (AE) tests are routinely done on living and deceased persons. There is anecdotal evidence suggesting an increase in age estimations due to the refugee crisis. Our aim is to determine the reasons and methods for performing dental AE tests in both living and deceased individuals. Global trends in AE over the past 10 years were also investigated. A database of all forensic laboratories was obtained and an electronic questionnaire was sent to all of them. The questionnaire was self-developed and included questions on the reasons for performing AE tests, the preferred methods used in living and deceased individuals, and the people/organizations who requested these AE tests. The number of tests performed annually varied between 0 and 500 and the majority were on asylum seekers, refugees, and for adoption cases. Most units used multiple techniques to determine the age among the living, but seldom used more than three techniques for the deceased. The majority of tests were requested by coroners and the legal fraternity. There has been an increase in the number of dental AEs carried out and this has been mostly due to asylum seekers and refugees. The most common techniques for the living were variations of Demirjian's technique while country specific techniques were used for the deceased.

Nasal reconstruction of a patient with complete congenital arhinia: A clinical report.

Complete congenital arhinia is a rare embryonic disorder of unknown etiology. This is a clinical report of the prosthetic nasal rehabilitations done in the early childhood and adolescent stages of a patient with complete congenital arhinia. Additive manufacturing techniques for creating presurgical planning models to assist in the creation of new nasal passages are also described. These rare disorders can be successfully rehabilitated if patients are sufficiently motivated and there is meticulous planning and collaboration from a multidisciplinary team.

Applications of rapid prototyping technology in maxillofacial prosthetics.

PURPOSE: The purpose of this study was to compare the accuracy, required time, and potential advantages of rapid prototyping technology with traditional methods in the manufacture of wax patterns for two facial prostheses. MATERIALS AND METHODS: Two clinical situations were investigated: the production of an auricular prosthesis and the duplication of an existing maxillary prosthesis, using a conventional and a rapid prototyping method for each. Conventional wax patterns were created from impressions taken of a patient's remaining ear and an oral prosthesis. For the rapid prototyping method, a cast of the ear and the original maxillary prosthesis were scanned, and rapid prototyping was used to construct the wax patterns. For the auricular prosthesis, both patterns were refined clinically and then flasked and processed in silicone using routine procedures. Twenty-six independent observers evaluated these patterns by comparing them to the cast of the patient's remaining ear. For the duplication procedure, both wax patterns were scanned and compared to scans of the original prosthesis by generating color error maps to highlight volumetric changes. RESULTS: There was a significant difference in opinions for the two auricular prostheses with regard to shape and esthetic appeal, where the hand-carved prosthesis was found to be of poorer quality. The color error maps showed higher errors with the conventional duplication process compared with the rapid prototyping method. CONCLUSION: The main advantage of rapid prototyping is the ability to produce physical models using digital methods instead of traditional impression techniques. The disadvantage of equipment costs could be overcome by establishing a centralized service.

Prosthodontic treatment of the edentulous adult cleft palate patient.

Clefts of the upper lip and plate are relatively common, yet dental treatment of these patients is still very poor and many grow up suffering dental neglect. Dental practitioners should become involved in the treatment team as dental needs are present from birth to death. Adult cleft patients often need tooth replacement with obturation of any residual clefts. They are best treated with tooth-supported removable appliances including partial and complete overdentures, thus preservation of their natural dentition is desirable. Edentulous cleft palate patients present with restorative difficulties due to their compromised maxillary arches as well as the presence of scar tissue in their palates and lips. An outline of these complications and guidelines for their treatment is illustrated in the form of three case reports from members of one family all presenting with varying cleft lip and palate defects. This article highlights the need for dental students to be exposed to dentally compromised patients so that they will feel confident enough to treat them in private practice.

A mechanically retained, four part oral and facial prosthesis: a clinical report.

The design of a prosthesis depends not only on anatomical and physiological factors, but also needs to encompass patient's socio-economic limitations and psychological needs. A four-part prosthesis for a patient with a maxillary and orbital defect was designed to be easy for the patient to insert, remove and clean, retentive without requiring sophisticated attachments or the use of adhesives, and made from economically viable materials. The denture was attached to an acrylic resin core which in turn clipped into a silicone glove obturator. The facial section fastened onto the ocular "button" on a larger, separate core, which then connected into the orbital opening of the obturator. The entire assembly was self-retentive, yet each component could also be worn separately if the need arose. This provided a functional prosthesis as well as psychological benefits to the patient who had no access to medical facilities or supplies in her rural home town.

Prosthodontic rehabilitation of a patient with total avulsion of the maxilla: a clinical report.

Patients with complete avulsion of the palate may require extensive surgical and prosthodontic rehabilitation. The prosthesis should replace not only missing teeth but also lost soft tissues and bone, including the hard palate, residual alveolar ridges, and in some situations, the soft palate. This clinical report describes the prosthetic rehabilitation, after appropriate surgical options had been exhausted, of a patient with bilateral traumatic avulsion of the maxilla.