Influence of Cortical Layer and Surgical Techniques on the Primary Implant Stability in Low-density Bone: An In Vitro Study.

AIM: This study aimed at evaluating the influence of cortical layer and surgical techniques on the primary stability of implants in low-density bone. MATERIALS AND METHODS: Two solid rigid polyurethane blocks with a density equivalent to 0.32 g/cm3 simulating cancellous bone were used. A short fiber-filled epoxy resin sheet of 2 mm was layered to one block to simulate cortico cancellous bone. A total of 40 implants were used in this study (n = 40). Twenty implants each (n = 20) were inserted in cancellous (Group 1) and cortico-cancellous bone (Group 2), of which 10 implants each (n = 10) were placed using undersized preparation technique with surgical drills-A and osteotomes-B, in both the groups. Insertion torque (IT) and implant stability quotient (ISQ) for each implant placed were assessed to determine the primary stability of each implant using a digital torque meter and resonance frequency analyzer, respectively. The values were statistically analyzed using an independent t-test (p < 0.05). Pearson's correlation analysis was performed to correlate between IT and ISQ. RESULTS: Technique B resulted in significantly higher IT and ISQ values in Group 1 (27.69 ± 1.2 N cm; 52.5 ± 1.05 ISQ) and Group 2 (38.8 ± 0.87 N cm; 70.1 ± 1.04 ISQ) compared to those with technique A (22.40 ± 1.62 N cm; 41.75 ± 1.20 ISQ and 33.24 ± 0.67 N cm; 63.72 ± 1.33 ISQ), respectively. Group 2 exhibited significantly higher IT and ISQ values as compared to Group 1 irrespective of the surgical technique employed (p < 0.05). CONCLUSION: The presence of the cortical layer significantly influenced the primary stability and preparing low-density bone with an undersized preparation technique using osteotomes that significantly increased the IT and ISQ. CLINICAL SIGNIFICANCE: Undersizing the preparation site considerably will help achieve a significant increase in primary stability in the poor quality bone as in the posterior maxilla, thereby contributing to the success of the implant.

Comparison of the effect of implant abutment surface modifications on retention of implant-supported restoration with a polymer based cement.

BACKGROUND: In cement-retained implant-supported restoration it is important to gain adequate retention of definitive restoration as well as retrievability of prosthesis. The surface of the abutment, alloy of the restoration and the type of cement used influences the retention of the restoration. There is a need to analyze the influence of surface modifications of abutments on the retentive capabilities of provisional implant cements. PURPOSE OF STUDY: To compare the effect of implant abutment surface modifications on retention of implant-supported restoration cemented with polymer based cement. MATERIALS AND METHOD: Thirty solid titanium implant abutments (ADIN), 8mm height, were divided into 3 groups. Ten abutments with retentive grooves (Group I) as supplied by the manufacturer, Ten abutments milled to 20 taper circumferentially (Group II), and Ten abutments milled and air-abraded with 110 µm aluminum oxide (Group III) were used in this study. Ni-Cr coping were casted for each abutment and polymer based cement was used to secure them to the respective abutments. Using a universal testing machine at a crosshead speed of 0.5 cm/minute, tensile bond strength was recorded (N). RESULTS: Mean tensile bond strength of Group I, II and III were found to be 408.3, 159.9 and 743.8 Newton respectively. The values were statistically different from each other (p<0.001). CONCLUSION: Abutments with milled and sandblasted surface provide the highest retention followed by abutments with retentive grooves and then by abutments with milled surface when cast copings were cemented to implant abutments with polymer based cement. CLINICAL IMPLICATIONS: Retention of restoration depends on the surface of the abutment as well as the luting agents used. Incorporation of retentive grooves or particle abrasion can enhance retention especially in situation of short clinical crown.

Restoration of failing maxillary implant-supported fixed prosthesis with cross arch splinted unilateral zygomatic implant: a clinical report.

Management of one or more failing distal implants in an implant supported fixed prosthesis in a completely edentulous maxilla creates a challenging situation. Restoring immediate function with additional implants in such a situation can be a challenge considering the loss of supporting bone, need for grafting, age, and the patient's desire for immediate fixed dental prosthesis. This clinical report describes a situation where a zygomatic implant has been placed unilaterally and splinted with osseointegrated conventional implants by an immediate fixed provisional restoration.