Is dynamic computer-assisted surgery more accurate than the static method for dental implant placement? A systematic review and meta-analysis.

STATEMENT OF PROBLEM: Dynamic computer-assisted surgery for dental implant placement has become popular, but systematic comparisons of the accuracy of computer-assisted surgery with static surgery are lacking. PURPOSE: The purpose of this systematic review and meta-analysis was to determine evidence on the difference in the accuracy of dynamic computer-assisted surgery compared with the static method for dental implant placement. MATERIAL AND METHODS: A systematic search was conducted in 3 electronic databases: PubMed, Ovid, and Cochrane. Studies conducted on dental implants that compared the accuracy of positioning implants with a dynamic system with that of a static system were included. Randomized clinical trials, prospective and retrospective cohort studies, and in vitro studies were included in the review. Review articles, case reports, letters, opinion articles, commentaries, and nonpeer-reviewed literature were excluded. RESULTS: Of the 26 full-text articles, 14 fulfilled the inclusion criteria. Of these, 2 were randomized clinical trials, 2 were prospective studies, and 1 was a retrospective cohort study. The remaining 9 were in vitro studies. A total of 1633 implants were placed with the static and 902 with the dynamic method. A significant mean difference (-0.51 degrees [95% CI: -0.90, -0.13]) between dynamic and static systems was only observed in the angular deviation of in vitro studies (P=.009). Meta-analysis was performed using Review Manager statistical software and forest plots were generated. CONCLUSIONS: A difference was found in the angular deviation of implants placed with the dynamic approach compared with the static system. The dynamic system was better, but this difference was not demonstrable in clinical studies. No significant difference was found in the apical and coronal deviations of the dynamic and static systems.

Comparison of patient satisfaction between complete dentures fabricated using "conventional" and "cephalometric angular reconstruction" vertical dimension procedures: A multicenter randomized clinical trial.

Aim: In Prosthodontics, during complete denture fabrication, conventional methods employed to determine occlusal vertical dimension require patient co-operation. Hence, the aim of the present study is to evaluate the clinical effectiveness of the 'cephalometric angular reconstruction' procedure in the calculation of these lost dimensions. Settings and Design: Multicentric randomised clinical trial conducted in four dental hospitals. Materials and Methods: Fully edentulous people who came to the hospitals for complete denture treatment were recruited into the study. Those who fulfilled the inclusion criteria were randomly assigned to two groups; Group 1: Dentures fabricated using a 'conventional' procedure and Group 2: Dentures fabricated using 'cephalometric angular reconstruction'. The patient's level of satisfaction was assessed on a scale of 1 to 5; 1-dissatisfaction to 5-excellent. The confounding factors that can influence the satisfaction were also recorded. Statistical Analysis Used: The distribution of patient's satisfaction was assessed using Chi-square test, whereas the difference between the two groups was evaluated using Mann-Whitney test. Results: There was no significant difference either in the vertical dimension determined (P = 0.465) or the patient's level of satisfaction (P = 0.943) between the two groups. There was no influence of confounding factors considered in the present study on the satisfaction levels. There was no difference in the distribution of satisfaction levels based on the dentist's quality assessment (P = 0.243). Conclusion: Complete dentures fabricated using cephalometric angular reconstruction procedure of vertical dimension determination were equivalent with respect to patient satisfaction, compared to those made using a conventional method. Hence, the new method can be clinically recommended during denture fabrication.

Thermal expansion and corrosion resistance of cobalt-chromium alloys fabricated by contemporary manufacturing processes: an in vitro study / Expansión térmica y resistencia a la corrosión de aleaciones de cobalto-cromo fabricadas mediante procesos de abricación contemporáneos: un estudio in vitro

In Purpose: The fabrication technique can influence the mechanical properties of Cobalt-Chromium (Co-Cr) dental alloys. Hence, the present study aims to determine the corrosion resistance and thermal expansion of alloys manufactured using three contemporary techniques. Material and Methods: A total of nine specimens of Co-Cr alloy were prepared according to ISO 22674 by each one of the three manufacturing processes (three in each process); conventional casting, direct metal laser sintering (DMLS) and milling (MIL). All these specimens were tested for coefficient of thermal expansion and corrosion resistance. The data was tabulated and analyzed statistically. Results: The difference in the thermal expansion of alloys fabricated using three techniques was non-significant at almost all the temperatures from 50 ºC to 950 ºC (p>0.05), except 450 ºC and 600 °C. The polarization resistance of specimens manufactured using the conventional method was more compared to DMLS and MIL at pH 5 (Conventional>MIL>DMLS) (p<0.001). Conclusion: The thermal expansion behavior of alloys manufactured using the three selected techniques were similar, whereas, at acidic pH, the corrosion resistance of conventional and MIL were better than the DMLS.

Antecedentes: La técnica de fabricación puede influir en las propiedades mecánicas de las aleaciones dentales de cobalto-cromo (Co-Cr). Por lo tanto, el presente estudio tiene como objetivo determinar la resistencia a la corrosión y la expansión térmica de aleaciones fabricadas con tres técnicas contemporáneas. Material y Métodos: Se prepararon un total de nueve probetas de aleación de Co-Cr según ISO 22674 por cada uno de los tres procesos de fabricación (tres en cada proceso); fundición convencional, sinterización directa de metal por láser (DMLS) y fresado (MIL). Todos estos especímenes fueron probados para determinar el coeficiente de expansión térmica y la resistencia a la corrosión. Los datos fueron tabulados y analizados estadísticamente. Resultados: La diferencia en la dilatación térmica de las aleaciones fabricadas con las tres técnicas no fue significativa en casi todas las temperaturas desde 50ºC hasta 950ºC (p>0,05), excepto 450ºC y 600ºC. La resistencia a la polarización de las muestras fabricadas con el método convencional fue mayor en comparación con DMLS y MIL a pH 5 (Convencional>MIL>DMLS) (p<0, 0 01). Conclusión: El comportamiento de expansión térmica de las aleaciones fabricadas con las tres técnicas seleccionadas fue similar, mientras que, a pH ácido, la resistencia a la corrosión de la convencional y la MIL fue mejor que la de la DMLS.

Estimation of occlusal vertical dimension using cephalometric angular reconstruction.

AIM: To propose a new technique, based on cephalometrics for determining the vertical dimension of occlusion (VDO). METHODS AND MATERIAL: Thirty-five participants in the age range of 20. ­: 22 years who met the inclusion criteria were recruited. Lateral cephalograms were obtained and tracing done. Five reference landmarks, Nasion (N), Anterior Nasal Spine (ANS), Porion (P), Gonion (G) and Gnathion (Gn) were marked and joined to form four angles, N-ANS-Gn, N-ANS-G, P-G-Gn and P-G-ANS; distance between ANS and Gn was considered as VDO in cephalogram (VDO-Ceph). The angles N-ANS-Gn and N-ANS-G; P-G-Gn, and P-G-ANS were correlated; two simple linear regression models were developed to predict N-ANS-Gn and P-G-Gn, using N-ANS-G and P-G-ANS, as independent variables. Using the formulae, the predicted angles, N-ANS-Gn and P-G-Gn were drawn and intersection marked as 'reconstructed point Gn'. The predicted VDO-Ceph values (distance between ANS and reconstructed Gn) were measured and correlated with actual values. RESULTS: The angles N-ANS-Gn and P-G-Gn had a statistically significant positive correlation with N-ANS-G (r = 0.77, P < 0.001) and P-G-ANS (r = 0.83, P < 0.001), respectively. Using simple linear regression analysis, the following formulae were obtained: N-ANS-Gn (in degrees) = 1.271 N-ANS-G (in degrees) + 24.83 and P-G-Gn (in degrees) = 0.987 P-G-ANS (in degrees) + 35.93. The predicted and actual VDO-Ceph values showed no statistical significance difference (P = 0.92). CONCLUSION: By tracing four cephalometric landmarks, N, ANS, P, G; and using the angular reconstruction, it is possible to predict the location of Gn. Hence, during prosthetic replacement of lost teeth, this can be employed for the estimation of lost dimensions.

Effect of proton pump inhibitors on dental implants: A systematic review and meta-analysis.

AIM: The present systematic review aims to determine the evidence on the impact of proton pump inhibitors (PPIs) on dental implants. SETTINGS AND DESIGN: This secondary qualitative and quantitative research was done using a pre-specified question and inclusion criteria. MATERIALS AND METHODS: A systematic search was conducted in electronic databases such as PubMed, Ovid, and Cochrane. All the studies that assessed the effect of PPIs on dental implants were included, irrespective of the design. Literature review, letter to editors, short commentaries, and opinion articles were excluded. RESULTS AND STATISTICAL ANALYSIS USED: A total of three publications fulfilled the inclusion criteria. All these included articles were retrospective cohort studies; the methodological quality was assessed using Newcastle-Ottawa scale. A total of 452 implants were placed in 149 PPI users, whereas 6798 were positioned in 2241 nonusers. Of these, 43 and 212 implants failed in users and nonusers, respectively (odds ratio: 2.91, 95% confidence interval: 2.06-4.11). The meta-analysis was performed using the statistical software Review Manager, and a fixed-effect model was used to obtain the odds ratio. The success rate of implants based on age, gender, smoking, and bone augmentation could be combined only from two studies, which revealed a considerable effect of these factors. CONCLUSION: As far as the available evidence is considered, it seems as if the usage of PPI has a detrimental effect on the success of dental implants. This influence needs justification as none of the included studies segregated the data based on confounding factors. Hence, there is a need to conduct well-designed, prospective, randomized clinical trials with balanced confounding factors to derive a proper conclusion.

Comparison of stress induced in mandible around an implant-supported overdenture with locator attachment and telescopic crowns - a finite element analysis.

INTRODUCTION: One of the principle factors for the success of implant supported/retained overdentures (IOs) is the manner in which the stresses are transferred to the surrounding bone. Hence, the aim of the present study is to compare the stress induced in the mandible around IOs, using two different attachment systems, locator and telescopic. METHODS: 3D finite element models were prepared using Pro/ENGINEER or PTC Creo to simulate 4 clinical situations: IOs using two different attachment systems, locator and telescopic, with and without splinting. A vertical compressive load of 35N was directed toward the central fossa in the molar region of each overdenture. Non-linear static contact analysis was carried out to determine the stress distribution in various components of IOs. Then, the models were analyzed by a finite element program ABAQUS, and displayed using Von Mises stress patterns. RESULTS: The contact stress values developed on the implant and attachment components were lower with locator attachment, in both splinted and non-splinted models. On the other hand, the stress distribution to the cortical bone was more with non-splinted/splinted locator attachments (3.73/4.12 Mega Pascals) when compared to the non-splinted/splinted telescopic attachments (2.66/3.7 Mega Pascals). The stresses in all the components of overdenture were greater with the splinted model compared to non-splinted, in both the attachment systems. CONCLUSION: The locator attachment might demonstrate superior clinical performance, as the stresses on implant and attachment components were less compared to telescopic. Non-splinted model showed better results in both the attachment types.

Safety profile of phentolamine mesylate as reversal agent of pulpal and soft tissue dental anesthesia: a systematic review and meta-analysis.

OBJECTIVE: To systematically review the safety of phentolamine mesylate as a reversal agent for pulpal and soft tissue dental anesthesia. DATA SOURCES: Comprehensive search, up to August 2018, was performed in three major electronic databases. The methodologic quality of all the included studies was assessed using Cochrane Collaboration for randomized clinical trials. RESULTS: A total of nine studies were included for qualitative and quantitative assessment. The number of events was 269 in 2,057 participants in the phentolamine mesylate group, and 179 in 1,338 participants of the control group (odds ratio 1.19; 95% confidence interval 1.03 to 1.39). In the data segregated based on age, four studies conducted on children and adolescents revealed an odds ratio of 0.68, whereas two studies on adults revealed an odds ratio of 1.58. CONCLUSION: There were no severe complications reported in any of the included studies, but the occurrence of adverse events (mild and moderate) was greater in the phentolamine mesylate group compared to the control group. Age has a significant effect on the possibility of adverse events with phentolamine mesylate.

Adverse Effects of Implants in Children and Adolescents: A Systematic Review.

OBJECTIVE: To determine the evidence on the adverse effects of placing dental implants in healthy growing children. STUDY DESIGN: A systematic search was conducted in five electronic databases: PubMed, Ovid, Cochrane, EBSCO host, ProQuest. Studies on implants placed in children below the age of 19 years, with loss of tooth either due to trauma or caries were included, whereas, studies on mini implants and implants placed due to congenital absence of teeth were excluded. The articles that fulfilled the inclusion criteria were analyzed based on the predetermined criteria of success. RESULTS: A total of 8 publications fulfilled the inclusion criteria. All the included articles were case reports/series, involving a total of 16 implants (15 maxillary, one mandibular) in 11 adolescents (7 boys and 4 girls). The age of implant placement ranged between ten to 17 years with a mean age of 13.4 years and the follow up period, 4.5 months to 13 years. Pain, paresthesia, mobility or peri-implant radiolucency was not reported in any case report, indicating good integration. Radiographic crestal bone loss, probing depth and implant esthetics were not mentioned. The infraocclusion was not reported in 5 cases (age: 11-17 years, follow up: 4.5 months-two years), however, it was an adverse effect in 6 cases (age: ten-17 years, follow up: three-13 years). CONCLUSION: There is insufficient evidence to contradict the placement of dental implants in healthy growing children; the only reported adverse event is infraocclusion, the management of which too is discussed. However, as all the data is from case reports, the result should be interpreted with caution. Therefore, well-designed randomized controlled trials are needed to address this gap in the literature.

Comparative effect of implant-abutment connections, abutment angulations, and screw lengths on preloaded abutment screw using three-dimensional finite element analysis: An in vitro study.

PURPOSE: The purpose of this study is to compare the effect of implant-abutment connections, abutment angulations, and screw lengths on screw loosening (SL) of preloaded abutment using three dimensional (3D) finite element analysis. MATERIALS AND METHODS: 3D models of implants (conical connection with hex/trilobed connections), abutments (straight/angulated), abutment screws (short/long), and crown and bone were designed using software Parametric Technology Corporation Creo and assembled to form 8 simulations. After discretization, the contact stresses developed for 150 N vertical and 100 N oblique load applications were analyzed, using ABAQUS. By assessing damage initiation and shortest fatigue load on screw threads, the SL for 2.5, 5, and 10 lakh cyclic loads were estimated, using fe-safe program. The obtained values were compared for influence of connection design, abutment angulation, and screw length. RESULTS: In straight abutment models, conical connection showed more damage (14.3%-72.3%) when compared to trilobe (10.1%-65.73%) at 2.5, 5, and 10 lakh cycles for both vertical and oblique loads, whereas in angulated abutments, trilobe (16.1%-76.9%) demonstrated more damage compared to conical (13.5%-70%). Irrespective of the connection type and abutment angulation, short screws showed more percentage of damage compared to long screws. CONCLUSIONS: The present study suggests selecting appropriate implant-abutment connection based on the abutment angulation, as well as preferring long screws with more number of threads for effective preload retention by the screws.

Determination of vertical dimension of occlusion using lateral profile photographs: A pilot study.

PURPOSE: To hypothesize a new theory based on soft tissue reference points on lateral profile photographs (LPPs) for determining the vertical dimension of occlusion (VDO), as there is need to explore for simple strategies. MATERIALS AND METHODS: Fifty-three participants in the age range of 20-27 years who met the inclusion criteria were recruited. LPPs were taken for all participants using standard protocol and duplicate copies obtained, on which five soft tissue reference points, nasion (Stn), subnasale (Stsn), porion (Stp), gnathion (Stgn), and gonion (Stg) (Stg prenoted on the face) were marked and joined to form angles; distance between Stsn and Stgn was considered as VDO in LPP (VDO-LP). The angle formed between Stn-Stsn-Stgn and Stn-Stsn-Stg; Stp-Stg-Stgn and Stp-Stg-Stsn was correlated; two simple linear regression models were developed to predict Stn-Stsn-Stgn and Stp-Stg-Stgn using Stn-Stsn-Stg and Stp-Stg-Stsn as independent variables. Using the formulae, VDO-LP predicted was constructed and correlated with the actual values. RESULTS: The angle Stn-Stsn-Stgn had a statistically significant moderate positive correlation with Stn-Stsn-Stg (r = 0.57, P < 0.001) and angle Stp-Stg-Stgn, a significant strong positive correlation with Stp-Stg-Stsn (r = 0.81, P < 0.001). Using simple linear regression analysis, the following formulae were obtained: Stn-Stsn-Stgn (in degrees) = 0.776 Stn-Stsn-Stg (in degrees) +79.01 and Stp-Stg-Stgn (in degrees) =1.331 Stp-Stg-Stsn (in degrees) +10.2. The predicted and actual VDO-LP values were in strong positive correlation with a coefficient of 0.8. CONCLUSION: With the use of simple landmarks on LPP, it is possible to reconstruct the lost facial dimensions during prosthetic replacement of lost teeth.

Freeway space determination using lateral profile photographs: A pilot study.

STATEMENT OF PROBLEM: Many methods are reported in literature to determine freeway space (FWS), but they yield dissimilar measurements. PURPOSE: Recording FWS of patients during prosthetic rehabilitation is one of the important steps in dentistry. The purpose of this study is to evaluate the ability to predict FWS using lateral profile photographs (LPPs) in edentulous participants. MATERIALS AND METHODS: Fifty-three participants in the age range of 20-27 years who met the inclusion criteria were recruited. LPP were taken for all participants using standard protocol and duplicate copy obtained; on which three soft tissue reference points, porion (Stp), gnathion (Stgn), and gonion (Stg) (Stg prenoted on the face) were marked and joined to form an angle Stp-Stg-Stgn. This angle was correlated with the mean FWS obtained using 3 methods, swallowing, phonetics, and no command. Simple linear regression model was used to develop a prediction formula for FWS using Stp-Stg-Stgn angle as the independent variable. RESULTS: The angle Stp-Stg-Stgn had a significant negative correlation with FWS (r = -0.76, P < 0.001). Using simple linear regression analysis, the following formula was obtained: FWS (in millimeters) = 11.405 - 0.072 × (Stp-Stg-Stgn angle in degrees). CONCLUSION: Within the limitations of this study, considering the usage of LPP as a method to determine the FWS can be recommended.

Effect of preparation convergence on retention of multiple unit restorations - An in vitro study.

BACKGROUND AND AIM: Convergence angle (CA) is one of the major determinant factors in the retention of single as well as multiple units. Hence, the aim of the present study was to determine the effect of preparation convergence on the retention of multiple unit restorations. MATERIALS AND METHODS: Nickel-chromium alloy single crowns as well as three, six and nine multiple unit fixed partial dentures (FPDs) were casted for standardized milled dies that simulate canine, premolar and molar teeth machined with two different degrees of convergence, 12 (n = 55) and 20 (n = 55). The dies were threaded on rectangular metal platforms with the help of retainer shaft in the proper position to model either single or multiple preparations. The casted crowns and FPDs were cemented and retention tested by securing the units in an Instron universal testing machine. The tabulated values were analyzed statistically using Mann-Whitney test. RESULTS: Single and multiple units with 12° CA needed greater force to dislodge compared to 20°, but this difference was not statistically significant for single units of premolar (P > 0.05). Irrespective of the angle, there was a simultaneous statistically significant increase in retention as the number of units increased in FPDs, except for the difference between 3 and 6 units in 20° group (P > 0.05). CONCLUSION: This study highlights the importance of emphasizing on CA, during canine and molar preparation for single units as well as preparation of canines for 6 units FPDs.

Early prosthetic management of maxillectomy, hemimandibulectomy patient with a lateral mid facial defect: a case report.

Maxillofacial prostheses for acquired defects have become more complex and sophisticated with advances in surgical, physical, and rehabilitative dentistry, but before planning, orofacial structures must be analyzed as to the specific cause and the consequent objectives of rehabilitation. Also retention of facial prostheses is very much challenging. Hence, we are presenting the fabrication of an interim prosthesis obturator and cheek prosthesis to restore the speech, help in deglutition and prevent drooling of saliva.

A staged approach of implant placement in immediate extraction sockets for preservation of peri-implant soft and hard tissue.

Esthetic zone restoration is a challenging aspect in implant dentistry because of two critical factors such as level of bone support and soft tissue dimensions. Preservation of healthy peri-implant tissues is of primary importance for ensuring better esthetics over an extended period. The aim of the present case-series was to evaluate a new staged approach of implant placement in immediate extraction sockets for preservation of peri-implant soft and hard tissues. Four subjects scheduled for extraction of teeth in the esthetic zone with neither a periapical nor periodontal infection and with thick tissue biotype were included. For all the subjects sand blasted, large grit, acid etched platform switched implant with a diameter 2 mm less than the diameter of extraction socket and a conical abutment-implant connection (Morse taper) were placed 2 mm below the crest of the socket, with almost 2 mm gap between the labial plate and the implant with shoulder placed palatally/lingually. The implants were loaded after 2 months healing period and followed for a period of 1-2 years. In all the four patients there was preservation of both hard and soft tissues around the implant with a good esthetic outcome in all the follow up visits. Integrating immediate placement with stable implant-abutment connection, platform switching concept and careful case selection, we can achieve a very good esthetic outcome.

Osseointegrated silicone finger prosthesis using dental implants: a renovated technique.

AIM AND BACKGROUND: In clinical practice, we come across patients with traumatically amputated or congenitally missing partial or complete fingers that can be restored using microsurgical replantation or transplantation procedures. However, in some cases this might not be possible due to systemic or local factors and the lost or missing part has to be replaced prosthetically to offer psychological and functional wellbeing. These prostheses can be constructed with various materials like acrylics or silicone retained with the help of auxiliary aids. However, these prostheses cause some hindrance in performing functions like writing, typing, etc. The aim of the present trial was to ameliorate the existing design of implant supported finger prosthesis. TECHNIQUE: Distal phalange of middle finger replaced with implant supported silicone finger prosthesis is modified by utilizing a metal framework to support silicone material to improve rigidity while working. CONCLUSION AND CLINICAL SIGNIFICANCE: We could achieve a good function, esthetics and tactile sensibility with this modified design. Whenever, feasible this design can improve the performance and patients feel a deep sense of satisfaction and improved self-esteem with this modified prosthesis.