Reconstruction of the Occipital and Parietal Congenital Defect with 3D Custom-Made Titanium Prosthesis: A Case Report with Four and a Half Years of Follow-Up and a Brief Review of Literature.

Management of patients with congenital skull defects requires a multidisciplinary approach. Considering the defect's location and size, brain protection, and the cosmetic outcome makes such reconstructions challenging. Due to limited resemblance to skull contour and donor site morbidity of autogenous bone grafts, alloplastic materials are widely used for skull reconstructions. Titanium alloys have proper strength values, low infection rates, favorable osseointegration property, and excellent marginal adaptability when manufactured by computer-aided design (CAD) and computer-aided manufacturing (CAM). A 13-year-old female patient presented with congenital defects at the superior third of occipital bone and posterior thirds of the bilateral parietal bones. On CT scan, the exact size and shape of the defect were determined. Using CAD/CAM, a 3D virtual model of the prosthesis was designed and then printed with titanium alloy (TiAl6V4) via additive manufacturing method. The prosthesis was placed on the defect in a total surgery time of only 90 minutes. On 4.5 years of follow-up, the contour of the skull was ideal and the skin over the defect and neurologic status was intact. Due to their biocompatibility and rigidity, custom-made titanium prostheses are promising options for reconstructing complex skull defects.

Computer-assisted horizontal translational osseous genioplasty: a simple method to correct chin deviation.

BACKGROUND: Different genioplasty techniques are applied for the adjustment of chin area deformities such as chin deviation. RESULTS: Thirty patients with simple facial asymmetry due to chin deviation underwent computer-assisted horizontal translational osseous genioplasty. In this technique, a surgical guide was used to cut a bone strip from the side where the chin should be transferred to; then, the same bone strip was used for the filling of the gap that was formed on the opposite side. CONCLUSION: According to the experience gained from this study, the authors believe that computer-assisted horizontal translational osseous genioplasty is a simple and reliable technique for patients with facial asymmetry due to chin deviation.

Deposition of Crystalline Hydroxyapatite Nanoparticles on Y-TZP Ceramic: A Potential Solution to Enhance Bonding Characteristics of Y-TZP Ceramics.

OBJECTIVES: Many advantages have been attributed to dental zirconia ceramics in terms of mechanical and physical properties; however, the bonding ability of this material to dental structure and/or veneering ceramics has always been a matter of concern. On the other hand, hydroxyapatite (HA) shows excellent biocompatibility and good bonding ability to tooth structure, with mechanically unstable and brittle characteristics, that make it clinically unacceptable for use in high stress bearing areas. The main purpose of this study was to introduce two simple yet practical methods to deposit the crystalline HA nanoparticles on zirconia ceramics. MATERIALS AND METHODS: zirconia blocks were treated with HA via two different deposition methods namely thermal coating and air abrasion. Specimens were analyzed by scanning electron microscopy, energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). RESULTS: In both groups, the deposition techniques used were successfully accomplished, while the substrate showed no structural change. However, thermal coating group showed a uniform deposition of crystalline HA but in air abrasion method, there were dispersed thin islands of HA. CONCLUSIONS: Thermal coating method has the potential to significantly alter the surface characteristics of zirconia. The simple yet practical nature of the proposed method may be able to shift the bonding paradigm of dental zirconia ceramics. This latter subject needs to be addressed in future investigations.

Mandibular Rami Implant: A New Approach in Mandibular Reconstruction.

PURPOSE: The mandible is an essential esthetic and functional component of the lower third of the face and its reconstruction has always been a challenge, especially after severe post-traumatic injuries. The purpose of the present report was to introduce a new approach of mandibular reconstruction in a patient who had lost the entire mandible except for the rami after being severely injured in a blast. MATERIALS AND METHODS: A new approach using a titanium mandibular rami implant technique was applied using computer-aided 3-dimensional virtual planning and rapid prototyping technology. A prosthetic component was supported by the mandibular implant, which achieved occlusion and dedicated function for the patient. RESULTS: This method offered precise adaptation of the implant and prosthesis and an easier surgical procedure, providing a shortened operation time, no donor site morbidity, and more predictable outcomes. CONCLUSION: This new technique allows reconstruction of large-scale mandibular defects that is not possible by conventional surgical methods.

Deposition of crystalline hydroxyapatite nano-particle on zirconia ceramic: a potential solution for the poor bonding characteristic of zirconia ceramics to resin cement.

The poor bonding strength of zirconia to different dental substrates is one of the challenging issues in restorative dentistry. Hydroxyapatite is an excellent biocompatible material with fine bonding properties. In this study, it was hypothesized that hydroxyapatite coating on zirconia would improve its bond strength. Forty-five zirconia blocks were prepared and randomly divided into three groups: hydroxyapatite coating, sandblasting, and no preparation (control). The blocks were bonded to cement and the micro-shear bond strength was measured following load application. The bond strength values were analyzed with the Kruskal-Wallis test in 3 groups and paired comparisons were made using the Mann-Whitney U test. The failure patterns of the specimens were studied by a stereomicroscope and a scanning electron microscope and then analyzed by the chi-square test (significance level = 0.05). Deposition of hydroxyapatite on the zirconia surface significantly improved its bond strength to the resin cement in comparison with the control specimens (p < 0.0001). Also, the bond strength was similar to the sandblasted group (p = 0.34). The sandblasted and control group only showed adhesive failure, but the hydroxyapatite coated group had mixed failures, indicating the better quality of bonding (p < 0.0001). As a final point, hydroxyapatite coating on the zirconia surface improved the bond strength quality and values.

Fracture Resistance of Zirconia Restorations with a Modified Framework Design.

OBJECTIVES: Chipping is one of the concerns related to zirconia crowns. The reasons of chipping have not been completely understood. This in-vitro study aimed to assess the effect of coping design on the fracture resistance of all-ceramic single crowns with zirconia frameworks. MATERIALS AND METHODS: Two types of zirconia copings were designed (n=12): (1) a standard coping (SC) with a 0.5mm uniform thickness and (2) a modified coping (MC) consisted of a lingual margin of 1mm thickness and 2mm height connected to a proximal strut of 4mm height and a 0.3mm-wide facial collar. After veneer porcelain firing, the crowns were cemented to metal dies. Afterwards, a static vertical load was applied until failure. The modes of failure were determined. Data were calculated and statistically analyzed by independent samples T-test. P<0.05 was considered statistically significant. RESULTS: The mean and standard deviation (SD) of the final fracture resistance equaled to 3519.42±1154.96 N and 3570.01±1224.33 N in SC and MC groups, respectively; the difference was not statistically significant (P=0.9). Also, the mean and SD of the initial fracture resistance equaled to 3345.34±1190.93 N and 3471.52±1228.93 N in SC and MC groups, respectively (P=0.8). Most of the specimens in both groups showed the mixed failure mode. CONCLUSIONS: Based on the results, the modified core design may not significantly improve the fracture resistance.

Efficacy of ProTaper and Mtwo Retreatment Files in Removal of Gutta-percha and GuttaFlow from Root Canals.

INTRODUCTION: The aim of this in vitro study was to compare the efficacy of ProTaper retreatment (ProTaper R) and Mtwo retreatment (Mtwo R) files in removing gutta-percha and GuttaFlow from endodontically treated straight root canals. METHODS AND MATERIALS: The root canals of 60 human mandibular single-rooted premolars were prepared and randomly divided into two groups (n=30). In groups A and B the root canals were obturated using lateral condensation of gutta-percha plus AH 26 and GuttaFlow, respectively. The canal orifices were temporarily sealed and the roots were incubated for 3 months at 37(º)C and 100% humidity. Primary cone-beam computed tomography (CBCT) images were taken after incubation period. The specimens in each group were randomly divided into two subgroups (n=15). ProTaper R files (D1, D2, and D3) were used in groups A1 and B1 while Mtwo R files (25/0.05 and 15/0.05) were used in groups A2 and B2. The time required to extirpate the root filling was also recorded. After retreatment, another CBCT scan was taken at the same position. The volume of remaining filling materials inside the canals was calculated before and after retreatment. The data was analyzed using the two-way ANOVA and independent t-test. RESULTS: The remaining filling materials in the canals treated with ProTaper were less than Mtwo. The remaining volume of GuttaFlow was less than gutta-percha regardless of the system applied. Mtwo R files removed root fillings faster than ProTaper R. CONCLUSION: ProTaper R removed filling material more efficiently compared to Mtwo R which required less time to remove root filling material.

The effect of multiple firings on microtensile bond strength of core-veneer zirconia-based all-ceramic restorations.

PURPOSE: Differences in core and veneer coefficients of thermal expansion, firing shrinkage, and speed of increasing and decreasing the temperature may generate stress in veneered all-ceramic restorations. Given the necessity of performing multiple firing cycles to achieve improved contour, color, and esthetics, the purpose of this study was to determine the effect of multiple firing cycles on the microtensile bond strength (MTBS) of zirconia core to the porcelain veneer in zirconia-based all-ceramic restorations. MATERIALS AND METHODS: Thirty blocks (12 × 12 × 4 mm(3)) of semi-sintered zirconia were machined and sintered according to manufacturer's instruction. Specimens were placed in three groups based on the number of firing cycles (4, 6, 8) for the veneering process. After veneering, the specimens were sectioned into microbars with 8 mm length and 1 mm cross-section. Twenty sound microbars in each group were stressed to failure in a microtensile tester machine at 1 mm/min. Fractured specimens were surveyed under a scanning electron microscope and classified as cohesive in core, cohesive in veneer, and mixed. MTBS data were analyzed using one-way ANOVA and Tukey test (p < 0.05). RESULTS: The mean MTBS (MPa) after 4, 6, and 8 firing cycles were 30.33 ± 2.13, 27.43 ± 1.79, and 25.06 ± 1.76, respectively. There was a statistically significant difference between the bond strengths of each of the three groups (p < 0.001). CONCLUSION: Increase in firing cycles decreased MTBS. Most of the failures (90-95%) in all three groups were cohesive in the veneering porcelain and did not change as the number of firing cycles increased.

Effect of a procedural video CD and study guide on the practical fixed prosthodontic performance of Iranian dental students.

Dental students in programs around the world typically pass preclinical courses before entering the clinic and working on actual patients. Since fixed prosthodontics is a preclinical course that requires a great deal of effort, students may experience a substantial amount of stress that may affect their self-confidence and/or clinical performance. In this study, an instructional video CD (VCD) and study guide depicting the step-by-step procedures involved in a metal-ceramic tooth preparation and provisional crown fabrication was prepared. Students at the Faculty of Dentistry, Tehran University of Medical Sciences, Tehran, Iran, were divided randomly into two groups. Group A students trained as usual with live patients, and Group B students were given a copy of the VCD and study guide following a lecture. The students in Group B were encouraged to read the study guide and watch the VCD after live demonstrations. Then, both groups practiced individually on mannequins. At the end of the course, the students completed a sixteen-item questionnaire about their stress level, self-confidence, and knowledge base. The results showed that the students exposed to the extra media performed significantly better on some practical phases, e.g., laboratory procedures. A moderate, insignificant correlation was detected between exposure to media and decreasing the students' stress and self-esteem. We concluded that supplementary teaching aids such as a VCD and study guide may improve the clinical performance of dental students to some extent, but the live demonstration is still preferred by students.

Modified flapless dental implant surgery for planning treatment in a maxilla including sinus lift augmentation through use of virtual surgical planning and a 3-dimensional model.

PURPOSE: The concept of "prosthetic-driven implantology" may be considered a turning point in the history of modern dental implantology. On the basis of this sophisticated approach, the available bone and the optimal prosthetic position of the future restoration are checked before surgical intervention. However, the major drawback of today's prosthodontic discipline is that it is inherently 2-dimensional in nature, which may prevent the appropriate treatment; this problem can be overcome by the 3-dimensional capability of a computer-assisted approach when performed judiciously. It was proposed that this technique has the potential to provide a high level of safety and accuracy in comparison to traditional surgical procedures. MATERIALS AND METHODS: Using a novel approach, we performed modified flapless implant surgery accompanied by a simultaneous sinus-lifting procedure. The technique used a 3-dimensional life-sized computer-aided design/computer-aided manufacturing (CAD/CAM) model prepared from the computed tomography images for prosthetic/surgical diagnosis and treatment planning. RESULTS: The procedure of implant planning, model surgery, and sinus floor augmentation in this sophisticated flapless surgical approach has the potential to provide substantial benefits for both patients and practitioners. CONCLUSIONS: The versatility of the described technique not only allows more accurate implementation of the treatment plan to the patient's mouth but also may offer many additional significant benefits, including the use of custom surgical guides, life-sized bone model manipulation, and surgical rehearsal, all of which are very difficult to achieve with current traditional procedures.

Custom-made radiographic template, computed tomography, and computer-assisted flapless surgery for treatment planning in partial edentulous patients: a prospective 12-month study.

PURPOSE: It was proposed that technologies derived from computer-aided design (CAD)/computer-aided manufacturing (CAM) and computed tomography may be useful for flapless implant treatment procedures. However, most of the studies examining the effectiveness of this method were performed in fully edentulous patients, with little or no attention paid to partially edentulous patients. The aims of this study were 1) to evaluate the concept of computer-assisted implant placement including a treatment planning procedure based on computed tomography scan images by use of a flapless surgical approach in partially edentulous cases and 2) to validate the reliability of this concept in a prospective 12-month clinical study. MATERIALS AND METHODS: Sixteen patients with partially edentulous areas in their mandibles were included in this study. A total of 57 implants were inserted by use of a CAD/CAM drill template, specially designed for flapless implant surgery. To assess the degree of pain and discomfort, the patients were examined at 2 days and 1 week after surgery. Patient satisfaction and implant functionality were further evaluated at follow-up intervals of 1, 3, 6, and 12 months postoperatively. A specially designed visual analog scale was used for data acquisition. RESULTS: The mean pain score on the visual analog scale at follow-up was within the range for little or no pain. Two implants failed early in 1 patient. All of the other implants were in a good functional state throughout the study. The mean marginal bone loss after 1 year of follow-up was 0.6 mm (SD, 0.2) mesially and 0.5 mm (SD, 0.1) distally. CONCLUSION: This prospective study showed that the use of CAD/CAM technology and flapless implant surgery may be considered reliable for partial edentulous patients.

Simultaneous immediate loading of implants and occlusal rehabilitation: a sophisticated treatment approach.

The concept of immediate loading has been well discussed in the literature. It was advocated that for success in immediate loading of implants, it is a prerequisite to know the bone quality/quantity as well as the biomechanical environment in which the implants are to be placed. In recent years, several attempts have been made to overcome the inherent inaccuracies of immediate loading by computer-assisted design/computer-aided manufacturing technologies. The purpose of this article is to introduce a novel approach for immediate treatment of a patient's mandible in accordance with correction of an occlusal scheme by using a series of specially designed appliances and principles of computer-assisted surgery/implantology.

Ceramic (Feldspathic & IPS Empress II) vs. laboratory composite (Gradia) veneers; a comparison between their shear bond strength to enamel; an in vitro study.

Patient demand for aesthetic dentistry is steadily growing. Laminates and free metal restorations have evolved in an attempt to overcome the invasiveness nature of full veneer restorations. Although many different materials have been used for making these restorations, there is no single material that fits best for all purposes. Two groups of ceramic material (Feldspathic and IPS Empress II) and one group of laboratory composite (Gradia) discs (10 discs in each group; 4 mm in diameter and 2 mm in thickness) were prepared according to the manufacturer's instruction. The surface of ceramic discs were etched and silanized. In Gradia group, liquid primer was applied on composite surfaces. Thirty freshly extracted sound human molars and premolars were randomly divided into three groups. The enamel surface of each tooth was slightly flattened (0.3 mm) on the buccal or lingual side and then primed and cemented to the prepared discs with the aid of a dental surveyor. The finishing specimens were thermocycled between 5 degrees C and 55 degrees C for 2500 cycles and then prepared for shear bond strength testing. The resulting data were analyzed by one-way anova and Tukey HSD test. The fractured surfaces of each specimen were inspected by means of stereomicroscope and SEM. There is significant difference between the bond strength of materials tested. The mean bond strengths obtained with Feldspathic ceramic, IPS Empress II and Gradia were 33.10 +/- 4.31 MPa, 26.04 +/- 7.61 MPa and 14.42 +/- 5.82 MPa, respectively. The fracture pattern was mainly mixed for ceramic groups. More scientific evidence needed for standardization of bonding protocols.

Computer-assisted implant surgery; a flapless surgical/immediate loaded approach with 1 year follow-up.

BACKGROUND: It has been suggested that for success with immediate loaded dental implants it is necessary that, prior to their placement, bone quantity and quality as well as the biomechanical environment in which the implants are to function be evaluated. However, conventional techniques currently used for immediate implant placement lack sufficient precision and are usually accomplished by opening flap procedures. The purpose of this paper is to report the benefit of sophisticated pre-operative diagnostic implant planning and a flapless surgical approach with immediate loading. METHODS: The report describes the use of computed tomography (CT) for three-dimensional (3D) evaluations of bone implant sites, an interactive software program for 3D planning and the fabrication of stereolithographic models as custom surgical templates. The degree of patient satisfaction was evaluated by periodic recall and by adopting a specially designed analogue scale in each visit. RESULTS: The mean amount of bone loss around the implants was 0.5 +/- 0.1 mm and the satisfactoriness scale was rated high (i.e. 81), at the end of 1 year. CONCLUSION: The use of stereolithographic appliances in accordance with flapless surgery makes immediate placement of the implants more predictable.

A novel stereolithographic surgical guide template for planning treatment involving a mandibular dental implant.

PURPOSE: In recent years, the concept of prosthodontic-driven implantology has received more attention. The precise placement of implants in accordance with greater safety and confidence allow the practitioner to offer a safer, more secure and predictable treatment than could previously be provided. In this report, this novel approach is illustrated through description of 1 difficult case. MATERIALS AND METHODS: Using principles of computer-assisted design and rapid manufacturing, the data acquisitioned from computerized tomography was used to plan implant rehabilitation and to transfer this information to the surgery as well. RESULTS: The procedure of implant planning in this sophisticated technique has potential to yield substantial public health benefits. CONCLUSIONS: It was demonstrated that the versatility of the technique allows not only precise translation of the treatment plan to the patient's mouth, but also offers many additional significant benefits including use of special guides during surgery which would be difficult to achieve with traditional procedures.

Flapless implant surgery: review of the literature and report of 2 cases with computer-guided surgical approach.

PURPOSE: Modern implantology uses techniques that can provide function, esthetics, and comfort with a minimally invasive surgical approach. Flapless implant surgery has been proposed to fulfill these requirements. Traditionally, flapless implant surgery was carried out by using a tissue punch technique, which may be potentially harmful because of the inherent blindness of the technique. The purpose of this article is to introduce a predictable flapless approach for treatment of 2 patients through principles of computer-guided implantology. MATERIALS AND METHODS: Using dedicated interactive computer software programs and 3D radiographic techniques such as computed tomography (CT), the precise location of each implant was planned. Using the concept "prosthetic-driven implantology," surgery was carried out for the rehabilitation of 2 patients. RESULTS: The procedure of implant planning in this sophisticated technique has potential to yield substantial public health benefits. CONCLUSION: Although this modern approach may have many advantages, transferring virtual planning to the patient's mouth has only been developed recently. Further research is required to justify this novel approach for implant rehabilitation.

Computer-assisted implantology: historical background and potential outcomes-a review.

BACKGROUND: The accurate transfer of preoperatively determined implant positions to the patient mouth is very beneficial to the dental practitioner as well as patients. The objective of this paper was to review the gradual development of computer-assisted implant surgery. METHODS: All of the major data sources including unpublished data in the internet are considered RESULTS AND CONCLUSIONS: Computer-assisted/-guided/-aided implantology has been founded to overcome the errors encountered during implant osteotomies and to position the implants more precisely. The protocols followed by this sophisticated technique are based upon the advocated concept of prosthetic-driven implantology and CT-scan analysis recently approved. Although several attempts have been made to improve this approach more and more, little has been done regarding the patient's demands, including cost. The inherent complexity of the techniques and materials utilized necessitates several degrees of training before attempting treatment and must be taken into account.