Rohana K. De Silva

Mandibular single‐implant overdentures: preliminary results of a randomised‐control trial on early loading with different implant diameters and attachment systems

OBJECTIVES To determine surgical and prosthodontic outcomes of mandibular single-implant overdentures, opposing complete maxillary dentures, using a wide diameter implant and large ball attachment system compared with different regular diameter implants with standard attachment systems. MATERIALS AND METHODS Thirty-six edentulous participants (mean age 68 years, SD 9.2) were randomly assigned into three treatment groups (n=12). A single implant was placed in the mandibular midline of participants to support an overdenture using a 6-week loading protocol. The control group received Southern regular implants and standard ball attachments. One group received Southern 8-mm-wide implants and large ball attachments. Another group received Neoss regular implants and Locator attachments. Parametric and non-parametric tests of a statistical software package (SPSS) were used to determine between groups differences in marginal bone loss, implant stability, implant, and prosthodontic success (P<0.05). RESULTS Implant success after 1 year was 75% for Southern regular implant (control) group; and 100% for the Southern wide and Neoss regular implant groups (P=0.038). Mean marginal bone loss at 1 year was 0.19 mm (SD 0.39) without significant differences observed. Implant stability quotient (ISQ) at baseline was significantly lower for the Southern regular (control) group than the other two groups (P=0.001; P=0.009). At 1 year, no significant difference in implant stability was observed (mean ISQ 74.6, SD 6.1). The change in implant stability from baseline to 1 year was significant for the control group (P=0.025). Prosthodontic success was comparable between the groups but the maintenance (41 events overall, mean 1.2) was greater for the Locator and the standard ball attachments. CONCLUSIONS Mandibular single-implant overdentures are a successful treatment option for older edentulous adults with early loading protocol using implants of different diameters and with different attachment systems.

Fractured zirconia implants and related implant designs: scanning electron microscopy analysis

OBJECTIVES Two fractured one-piece experimental (commercially unavailable) zirconia implants were analyzed using scanning electron microscope (SEM) analysis to identify failure origins and aid in understanding the failure mechanisms. Modifications to the zirconia implant design are suggested to minimize such fracture incidences. MATERIALS AND METHODS Two zirconia implants fractured during the final torquing in the maxillary ridge using the prescribed hand torque wrench. The implants were subsequently retrieved and prepared for optical and SEM evaluation. Critical attention was given to the fractography (crack morphology) of the fractured implants to identify the fracture origin. RESULTS Events related to initiation and propagation of the crack front could be detected from the morphology of the fractured surfaces. Unfavorable torque and bending forces applied on the implant during surgical placement and the inherent flaws in the material may have resulted in crack initiation and implant failure. CONCLUSIONS Caution must be exercised when placing zirconia implants in dense bone sites. Modification of surgical protocols for the intended implant site may be necessary. Improvement in design features specific to zirconia implants, and strict quality control during manufacture is essential to minimize the likelihood of fracture.

SIMULTANEOUS MODELLING OF THE MICHAELIS-MENTEN KINETICS OF PARACETAMOL SULPHATION AND GLUCURONIDATION

1 The aim of the present study was to perform an in vivo estimation of the Michaelis‐Menten constants of the major metabolic pathways of paracetamol (APAP). 2 A two‐occasion, single‐dose cross‐over trial was performed using 60 and 90 mg/kg doses of APAP in healthy patients undergoing third molar dental extraction. Plasma samples were collected over 24 h and urine was collected for 8 h after dosing. Twenty patients were enrolled in the study and complete data for plasma and urine were available for both doses for 13 volunteers who were included in the analysis; seven of the volunteers were men, the median age (range) was 22 years (19–31) and the median weight (range) was 68 kg (50–86). 3 The mean (95% CI) km for APAP glucuronidation was 6.89 mmol/L (3.57–10.22) and the Vmax was 0.97 mmol/h per kg (0.65–1.28). The km for APAP sulphation was 0.097 mmol/L (0.041–0.152) and the Vmax was 0.011 mmol/h per kg (0.009–0.013). For the combined excretion of APAP‐cysteine and APAP‐mercapturate, the km was 0.303 mmol/L (0.131–0.475) and the Vmax was 0.004 mmol/h per kg (0.002–0.005). 4 The estimates for in vivo Michaelis‐Menten constants for APAP glucuronidation and sulphation were in the order of those reported previously using in vitro methods.

Influence of a pedicle flap design on acute postoperative sequelae after lower third molar removal

Pain, swelling, trismus, and alveolar osteitis often occur after removal of impacted third molar teeth. To minimize these complications a number of mucoperiosteal flap designs have been advocated, but, to date, a pedicle flap design has not been evaluated. In a randomized prospective split mouth study, 52 participants had bilateral symmetrically impacted mandibular third molars removed over two sessions. A buccal envelope or pedicle flap was randomly assigned to the left or right third molar site. Pre-and postoperative pain and swelling were recorded using a standardized visual analogue scale, trismus was measured as the maximum inter-incisal opening distance in millimetres and dry socket was assessed clinically. Greater continuous pain, pain on maximum opening, and oro-facial swelling were recorded with the pedicle flap design. Continuous pain resolved significantly faster with this flap design (p<0.05). Trismus was similar for both flap designs (p>0.05). Five cases of alveolar osteitis occurred with the envelope flap whilst no cases developed with the pedicle flap, but the incidence was too small for statistical analysis. The pedicle flap improved some aspects of postoperative pain experience and reduced the incidence of alveolar osteitis, but further investigation with a larger sample size is required to evaluate its significance.

Soft and Hard Tissue Response to Zirconia versus Titanium One‐Piece Implants Placed in Alveolar and Palatal Sites: A Randomized Control Trial

Background Titanium (Ti) implants have been used in the last four decades to replace missing teeth. Alternatives to Ti such as zirconia (Zr) may offer aesthetic advantages and be more acceptable to patients and clinicians concerned about Ti allergy but must show equivalent biological acceptability to Ti. Purpose The research aimed to investigate soft and hard tissue response to Ti and Zr implants in edentulous patients. Materials and Methods The research included 24 participants (Ti = 12, Zr = 12) restored with one-piece ball-abutment implants to support overdentures. Participants received four maxillary implants (two in the premolar alveolus, one off center in the alveolar midline, and one wide-diameter implant in the anterior median palate) and three mandibular implants (one in the midline and bilateral posterior implants). Results Success rates for both Ti and Zr implants were low, 67.9% for all alveolar implants and a survival rate of 50.0% for the palatal implants. Only 11 (52.4%) of 21 palatal implants survived the follow-up period. Peri-implant health was equivalent for Ti and Zr implants and showed no statistically significant changes from loading to the 1-year follow-up. Statistically significant differences were noted in radiographic bone level between Ti and Zr implants (p = .02), with Zr showing greater bone loss. Conclusions Although the failure rates with the one-piece Zr implants were higher than with the Ti ones, suggesting that the formers clinical usage as in this study cannot be recommended, it should be borne in mind that the fault may also lie with the novel prosthodontic design which was used.BACKGROUND Titanium (Ti) implants have been used in the last four decades to replace missing teeth. Alternatives to Ti such as zirconia (Zr) may offer aesthetic advantages and be more acceptable to patients and clinicians concerned about Ti allergy but must show equivalent biological acceptability to Ti. PURPOSE The research aimed to investigate soft and hard tissue response to Ti and Zr implants in edentulous patients. MATERIALS AND METHODS The research included 24 participants (Ti = 12, Zr = 12) restored with one-piece ball-abutment implants to support overdentures. Participants received four maxillary implants (two in the premolar alveolus, one off center in the alveolar midline, and one wide-diameter implant in the anterior median palate) and three mandibular implants (one in the midline and bilateral posterior implants). RESULTS Success rates for both Ti and Zr implants were low, 67.9% for all alveolar implants and a survival rate of 50.0% for the palatal implants. Only 11 (52.4%) of 21 palatal implants survived the follow-up period. Peri-implant health was equivalent for Ti and Zr implants and showed no statistically significant changes from loading to the 1-year follow-up. Statistically significant differences were noted in radiographic bone level between Ti and Zr implants (p = .02), with Zr showing greater bone loss. CONCLUSIONS Although the failure rates with the one-piece Zr implants were higher than with the Ti ones, suggesting that the formers clinical usage as in this study cannot be recommended, it should be borne in mind that the fault may also lie with the novel prosthodontic design which was used.

Facial attractiveness of skeletal Class II patients before and after mandibular advancement surgery as perceived by people with different backgrounds.

The purpose of this study was to determine the perceived level of improvement in facial attractiveness as assessed by people with different backgrounds in skeletal Class II patients treated by mandibular advancement with bilateral sagittal split osteotomy (BSSO). The frontal and lateral pre- and post-operative photographs of 10 Caucasian patients were selected. Changes in frontal and profile attractiveness were assessed by 10 orthodontists, 10 art students, and 10 laypersons. Frontal and lateral pre- and post-operative photographs were randomly distributed throughout two surveys. For each photograph, the evaluators ranked the attractiveness of face, chin, and lips on visual analogue scales. A third survey was administered to orthodontists only, by presenting the same pre and post-operative photographs but paired side-by-side with pre- and post-operative status disclosed. Overall, attractiveness scores after BSSO showed an 11.5 per cent improvement (95 per cent confidence intervals: 9.4-13.5 per cent) on the lateral post-operative photographs and a 7.5 per cent improvement (95 per cent confidence intervals: 5.4-9.5 per cent) on the frontal post-operative photographs. Attractiveness scores differed significantly between the groups (P = 0.015), with orthodontists being more generous with their improvement ratings and the art students tending to give a more critical assessment. There were no significant differences between male and female evaluators (P > 0.05). Ratings of before-after attractiveness almost doubled when the pre- and post-operative status was disclosed as compared to blinded evaluations, thus indicating that prior knowledge of pre- and post-treatment status markedly influences aesthetic evaluations, with a bias towards a more favourable outcome.

Primary stability measurements of single implants in the midline of the edentulous mandible for overdentures

OBJECTIVES To determine the primary stability of the Southern wide diameter (8 mm) implants, Neoss regular diameter (4 mm) implants, and Southern regular diameter (3.75 mm) implants placed in the midline of edentulous mandibles for single-implant overdentures. Variables related to host site and implant characteristics were investigated to determine their influence on the primary stability of the implants. MATERIALS AND METHODS A total of 36 implants were placed in the midline symphysis of the edentulous mandibles of 36 participants. Their primary stability was then measured using the magnetic Osstell mentor device. Analysis of variance (ANOVA) was used to compare the mean implant stability quotient (ISQ) scores with one-way ANOVA for multiple comparisons. RESULTS The highest measurement (ISQ) of primary stability was for the Southern 8 mm wide diameter implants (84.8, SD 9.8), followed by the Neoss 4 mm regular diameter (82.3, SD 4.8) implants and the Southern 3.75 mm regular diameter implants (75.3, SD 8.4), respectively. The Southern 3.75 mm regular diameter implants had a significantly lower mean ISQ value than the same system 8 mm wide diameter (P=0.004) and the Neoss 4 mm regular diameter implants (P=0.03). No significant differences were observed between the 8 mm and the 4 mm diameter implants (P>0.05). CONCLUSIONS Host-site variables such as age, gender, bone volume, and quality do not appear to influence the primary stability of the implants. No clear correlation was established between ISQ values and implant diameter.

Could the median-palate accommodate wide-bodied implants in order to support maxillary over-dentures? A radiomorphometric study of human cadavers

INTRODUCTION Atrophy of the alveolar bone is an irreversible multifactorial phenomenon, the rate of which varies between individuals and between the jaws. This atrophy of the alveolar ridges presents severe limitations for the oral rehabilitation of the edentulous patients and poses a clinical challenge to the prosthodontists and implant surgeons. The present research aimed to investigate whether the median-palate of elderly edentulous subjects is anatomically suitable for implant placement. MATERIALS AND METHODS A total of 32 samples were harvested from the maxillae of 16 human cadavers. One dentate male subject was included for contrast. Bone quality and quantity were analysed at two regions: the median-palate and the edentulous maxillary alveolar ridge. Samples were scanned through micro-CT, and the region of analysis (ROA) identified and dissected. Bone volume to tissue volume ratio (%BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp) and trabecular bone pattern factor (Tb.Pf) were evaluated for the two regions using Skyscan CTAn(®). RESULTS The results of bone volume fraction obtained from CTAn(®) of the median-palatal region show higher values than the respective premolar sites in 12 of 15 (80%) edentulous samples. However, this difference was statistically non-significant (P = 0.06). Similarly, the trabecular number for 10 of 15 samples (66.6%) from the median-palate shows greater values than the respective premolar site (P = 0.07). Trabecular thickness of 10 of 15 (66.6%) premolar samples is larger than in the median-palatal region. However, these differences were also statistically non-significant (P = 0.25). Statistically significant difference (P = 0.04) was found between the Tb.Sp values of the two regions. CONCLUSION The results indicate that the anterior median-palate is structurally better than their respective maxillary premolar region in elderly edentulous persons, and an implant can be placed to anchor an overdenture. The best site for a wide-body implant was established to be 6-8 mm posterior to the incisive foramen in elderly edentulous patients.

Temporomandibular Joint Synovial Chondromatosis With Intracranial Extension: A Review and Observations of Patient Observed for 4 Years

The diagnosis is from the imaging and histologicfindings. The differential diagnosis includes osteoma,osteoblastoma, osteochondroma, condylar hyperpla-sia, chondroblastoma, chondrosarcoma, and osteosar-coma. The radiologic features of TMJ SC are nonspe-cific but can include calcified loose bodies, soft tissueswelling, widening of the joint space, alterations tothe joint surface, and sclerosis or hyperostosis of theglenoid fossa and/or mandibular condyle.

Maxillary Three-Implant Overdentures Opposing Mandibular Two-Implant Overdentures: 10-Year Surgical Outcomes of a Randomized Controlled Trial.

Background The surgical placement of four maxillary implants for overdentures may not be obligatory when opposing mandibular two-implant overdentures. Purpose To determine 10-year surgical outcomes and implant success of three narrow diameter implants in edentulous maxillae with conventional loading. Materials and Methods Forty participants with mandibular two-implant overdentures were randomly allocated for surgery for maxillary overdentures. Using osteotomes, three implants of similar systems were placed with a one-stage procedure and 12-week loading with splinted and unsplinted prosthodontic designs. Marginal bone and stability measurements were done at surgery, 12 weeks, 1-, 2-, 5-, 7-, 10 years. Results One hundred seventeen implants were placed in 39 participants, with 35 being seen at 1 year; 29 at 2 years; 28 at 5 years; 26 at 7 years; and 23 (59%) at 10 years. Marginal bone loss was 1.35 mm between surgery and 12 weeks; 0.36 mm between 12 weeks and 1 year; 0.48 mm between 1 and 5 years; and 0.22 mm between 5 and 10 years. Implant stability quotients were 56.05, 57.54, 60.88, 58.80, 61.17 at surgery, 12 weeks, 1 year, 5 years, and 10 years. Four-field tables by implant showed success rates of 82% at 1 year; 69.2% at 2 years; 66.7% at 5 years; 61.5% at 7 years; 51.3% at 10 years. Data showed no differences between surgical technique, systems, or prosthodontic designs. Conclusions Surgical placement with osteotomes of three narrow diameter implants for maxillary overdentures, opposing mandibular two-implant overdentures, is an acceptable approach, subject to strict patient selection. Implant success is independent of prosthodontic design.BACKGROUND The surgical placement of four maxillary implants for overdentures may not be obligatory when opposing mandibular two-implant overdentures. PURPOSE To determine 10-year surgical outcomes and implant success of three narrow diameter implants in edentulous maxillae with conventional loading. MATERIALS AND METHODS Forty participants with mandibular two-implant overdentures were randomly allocated for surgery for maxillary overdentures. Using osteotomes, three implants of similar systems were placed with a one-stage procedure and 12-week loading with splinted and unsplinted prosthodontic designs. Marginal bone and stability measurements were done at surgery, 12 weeks, 1-, 2-, 5-, 7-, 10 years. RESULTS One hundred seventeen implants were placed in 39 participants, with 35 being seen at 1 year; 29 at 2 years; 28 at 5 years; 26 at 7 years; and 23 (59%) at 10 years. Marginal bone loss was 1.35 mm between surgery and 12 weeks; 0.36 mm between 12 weeks and 1 year; 0.48 mm between 1 and 5 years; and 0.22 mm between 5 and 10 years. Implant stability quotients were 56.05, 57.54, 60.88, 58.80, 61.17 at surgery, 12 weeks, 1 year, 5 years, and 10 years. Four-field tables by implant showed success rates of 82% at 1 year; 69.2% at 2 years; 66.7% at 5 years; 61.5% at 7 years; 51.3% at 10 years. Data showed no differences between surgical technique, systems, or prosthodontic designs. CONCLUSIONS Surgical placement with osteotomes of three narrow diameter implants for maxillary overdentures, opposing mandibular two-implant overdentures, is an acceptable approach, subject to strict patient selection. Implant success is independent of prosthodontic design.