Comparison between Two Design Concepts of Four Implants Placement Used to Support Telescopic Mandibular Overdenture: A Prospective Study of Implant Marginal Bone Height Changes.

AIM: The aim of this present study was to compare two placement designs of four implants used to support a telescopic mandibular overdenture regarding the marginal bone height changes. MATERIALS AND METHODS: Each patient received four implants. Two anterior implants were installed vertically in the canine area. Patients were randomized into two groups according to the direction of posterior implants installed in the premolar area. Group I: where the implants were installed vertically parallel to the anterior implants and group II: where the implants were installed 30º distally. The implants were delayed loaded with a telescopic mandibular overdenture. The implant's marginal bone changes were evaluated after 6 and 12 months of overdenture insertion. RESULTS: Mean marginal bone loss of anterior implants showed a statistically significant difference between both groups. The vertically parallel posterior implants in group I showed statistically significant higher marginal bone loss than posterior implants in group II after follow-up periods. The 30º distally tilted posterior implants maintained the implant marginal bone after 12 months of overdenture insertion. CONCLUSION: Rehabilitation of the edentulous mandible with telescopic overdenture supported by four parallel implants is a promising successful treatment option. CLINICAL SIGNIFICANCE: Tilting the posterior implants will improve the anteroposterior spread that in turn increases the support and the survival rate of the implants. Also, using this technique gives us an opportunity to use fewer implants.

Peri-implant tissue health and patient satisfaction of vertical versus inclined posterior implants used to support overdentures with bar attachments. A one-year randomized trial.

INTRODUCTION: This study aimed to evaluate peri-implant tissue health and patient satisfaction of vertical and inclined posterior implants for mandibular bar overdentures. MATERIALS AND METHODS: Thirty edentulous participants received four implants in the interforaminal area of the mandible. The patients were randomly assigned into two equal groups; (1) vertical group (control): all implants were inserted vertically parallel to each other. Inclined group (study): the anterior implants were placed vertically, and the posterior implants were tilted 30° distally. Hader bar attachment with two 7 mm-distal cantilevers (vertical group) and without cantilevers (inclined group) was used to connect the implants to mandibular overdentures. Peri-implant tissue health (Plaque [PL] and gingival [GI] indices, pocket depth [PD], and crestal bone loss [CBL]) were evaluated after denture insertion (T0), 6 (T6), and 12 (T12) months after insertion. Patient satisfaction was evaluated using a visual analog scale after 12 months. RESULTS: At T12, the vertical group showed significantly higher PL, PD, and CBL than the inclined group for anterior (p < 0.037) and posterior (p < 0.017) implants. The vertical group showed significantly higher GI than the inclined group for anterior implants (p = 0.003), and the inclined group showed significantly higher GI than the vertical group for posterior implants (p = 0.016). The inclined group showed significantly higher scores for general satisfaction (p = 0.049), prosthesis as a part of you (p = 0.013), appearance (p < 0.001), stability (p = 0.002), ease of cleaning (p < 0.001), and comfort (p = 0.001) than the vertical group. CONCLUSION: Inclined posterior implants used to support mandibular bar overdentures are recommended than vertical implants, as it was associated with improved patient satisfaction and peri-implant tissue health.

Maxillary Bone Resorption with Conventional Dentures and Four-Implant-Supported Fixed Prosthesis Opposed by Distal-Extension Partial Dentures: A Preliminary 5-year Retrospective Study.

PURPOSE: The aim of this preliminary study was to evaluate maxillary bone resorption with conventional dentures and implant-supported prostheses opposed by distal-extension removable partial dentures (RPDs). MATERIALS AND METHODS: Fifteen patients (seven women and eight men) with totally edentulous maxillary ridges and partially edentulous mandibular ridges (Class I Kennedy classification) received maxillary fixed prostheses on four implants and mandibular distal-extension RPDs (study group). The control group consisted of 15 patients who received conventional maxillary dentures and distal-extension mandibular RPDs without any implant treatment but were matched to the study group and acted as a historical group. Evaluation of vertical maxillary bone resorption for both groups was made at the time of prosthesis insertion (T0) and 5 years later (T2) using the proportional area measurements made on digital panoramic radiographs for anterior and posterior areas. RESULTS: The control group showed significantly higher vertical bone loss than the test group (P < .001). The control group had 0.270 higher maxillary bone loss than the test group. For both groups, anterior maxillary areas showed significantly higher bone loss than posterior areas (P < .003). Anterior maxillary areas had 0.122 higher bone loss compared with posterior areas. Women had 0.035 higher maxillary bone loss compared with men. CONCLUSION: Within the limitations of this study, implant-supported fixed prostheses for the edentulous maxilla opposed by remaining mandibular anterior teeth reduce maxillary anterior and posterior alveolar bone loss compared with conventional dentures. However, they do not prevent maxillary bone loss.

Effect of two designs of implant-supported overdentures on peri-implant and posterior mandibular bone resorptions: a 5-year prospective radiographic study.

OBJECTIVES: The aim of this study was to evaluate and compare the effect of two designs of implant-supported overdentures on peri-implant and posterior mandibular bone resorptions after 5 years of follow-up. MATERIALS AND METHODS: Twenty edentulous patients were randomly assigned into two equal groups: Group I (GI), patients received overdentures supported and retained by cantilevered bars on two canine implants and Group II (GII), patients received overdentures retained by straight bars on two canine implants and supported by two-first molar implants. Peri-implant vertical (VBL) and horizontal (HBLO) bone losses were assessed on periapical radiographs at the time of overdenture insertion (T0), 6 months (T6 m), 1 year (T1), 3 years (T3), and 5 years (T5) after insertion. Posterior mandibular bone resorption was evaluated using proportional measurements (posterior area index, PAI) made on panoramic radiographs at T0 and T5. RESULTS: Group I recorded significant higher VBL than GII. VBL increased significantly with advance of time in both groups. Posterior implant recorded significant higher VBL than anterior implants in GII. HBLO did not differ significantly between groups or between observation times. Group I recorded significant higher PAI than GII at T5. Group, age, and initial height of the mandibular ridge were significantly correlated with PAI. CONCLUSION: Within the limitations of this study, regarding the small sample size, it could be concluded that overdentures retained by straight bars on two canine implants and supported by two-first molar implants present a clinical advantage in terms of peri-implant and posterior mandibular bone preservation compared to overdentures supported and retained by cantilevered bars on two canine implants after 5 years.

Retention and Stability of Implant-Retained Mandibular Overdentures Using Different Types of Resilient Attachments: An In Vitro Study.

PURPOSE: The aim of this study was to evaluate and compare the retention and stability of mandibular implant overdentures using different types of resilient attachments. MATERIALS AND METHODS: Two implant analogs were inserted in the canine areas of an acrylic edentulous mandibular model. A metal-reinforced experimental overdenture was constructed and connected to the implant analogs (on two occasions) using either resilient telescopic or Locator attachments. Locators were divided into three subgroups according to the degree of retention of the male nylon insert: Locator extra-light retention (blue insert), Locator light retention (pink insert), and Locator medium retention (transparent insert). Vertical and oblique (anterior, posterior, and lateral) dislodging forces were measured at the beginning of the study (initial retention) and after 540 cycles of denture insertion and removal (final retention). RESULTS: For all dislodging forces, Locator medium recorded the highest initial and final retention. Telescopic attachments recorded the lowest retention during vertical and anterior dislodging, and Locator extra-light recorded the lowest retention during lateral and posterior dislodging. For all types of Locator attachments, anterior dislodging recorded the highest initial and final retention, and lateral dislodging recorded the lowest retention. For the telescopic attachment, posterior dislodgment recorded the highest initial and final retention, and anterior dislodging recorded the lowest retention. CONCLUSION: After repeated denture insertions and removals, the highest retention and stability were recorded with Locator medium followed by Locator light. The lowest retention was recorded with resilient telescopic attachment, and the lowest stability was recorded with Locator extra-light.

Effect of different implant positions on strain developed around four implants supporting a mandibular overdenture with rigid telescopic copings.

OBJECTIVE: To evaluate and compare the effect of three different implant positions on strain developed around four implants supporting a mandibular overdenture with rigid telescopic attachments. METHOD AND MATERIALS: Three experimental acrylic resin overdentures were fabricated on three edentulous mandibular acrylic models. Four implants were placed in each model. According to the implant positions, the models were classified into three groups: in group I (quadrilateral design) the implants were placed at canine and first molar areas; in group II (curved design) the implants were placed at canine and second premolar areas; and in group III (linear design) the implants were placed at lateral incisor and first premolar areas. Overdentures were connected to the implants with rigid telescopic attachments. Eight linear strain gauges were bonded to the acrylic resin around each implant at two sites (mesial and distal). Strains were measured for anterior (lateral incisor and canine) and posterior (premolar and molar) implants at both mesial and distal sites during bilateral and unilateral load applications. RESULTS: For bilateral and unilateral load applications, group II recorded the highest strain values while group I recorded the lowest. In group II and group III, strain values at distal sites were significantly higher than values at mesial sites. Strain values of posterior implants were significantly higher than values of anterior implants in all groups. The greatest strain values were recorded at the loading side during unilateral load application. CONCLUSION: Quadrilateral design showed minimal peri-implant strain compared to curved or linear designs. This design may be recommended when rigid telescopic crowns are used to connect mandibular overdentures to four implants.

Comparison of immediate complete denture, tooth and implant-supported overdenture on vertical dimension and muscle activity.

PURPOSE: To compare the changes in the occlusal vertical dimension, activity of masseter muscles and biting force after insertion of immediate denture constructed with conventional, tooth-supported and Implant-supported immediate mandibular complete denture. MATERIALS AND METHODS: Patients were selected and treatment was carried out with all the three different concepts i.e, immediate denture constructed with conventional (Group A), tooth-supported (Group B) and Implant-supported (Group C) immediate mandibular complete dentures. Parameters of evaluation and comparison were occlusal vertical dimension measured by radiograph (at three different time intervals), Masseter muscle electromyographic (EMG) measurement by EMG analysis (at three different positions of jaws) and bite force measured by force transducer (at two different time intervals). The obtained data were statistically analyzed by using ANOVA-F test at 5% level of significance. If the F test was significant, Least Significant Difference test was performed to test further significant differences between variables. RESULTS: Comparison between mean differences in occlusal vertical dimension for tested groups showed that it was only statistically significant at 1 year after immediate dentures insertion. Comparison between mean differences in wavelet packet coefficients of the electromyographic signals of masseter muscles for tested groups was not significant at rest position, but significant at initial contact position and maximum voluntary clench position. Comparison between mean differences in maximum biting force for tested groups was not statistically significant at 5% level of significance. CONCLUSION: Immediate complete overdentures whether tooth or implant supported prosthesis is recommended than totally mucosal supported prosthesis.

Implant-supported versus implant-retained distal extension mandibular partial overdentures and residual ridge resorption: a 5-year retrospective radiographic study in men.

PURPOSE: This retrospective study sought to examine posterior mandibular ridge resorption under implant-supported and implant-retained distal extension partial overdentures in men at the end of a 5-year observation period. MATERIALS AND METHODS: Class I mandibular partial edentulism was managed in 34 patients with removable partial overdentures that were adjunctively supported (n = 18) or retained (n = 16) via resilient attachments placed bilaterally on single implants (n = 68) in the first molar areas. Posterior Area Indices (PAI) were calculated for each patient by digitizing the traced rotational tomograms taken immediately before and after 5 years of treatment. Proportional rather than actual measurements were used in an effort to minimize errors related to magnification and distortion. RESULTS: Residual ridge resorption associated with the implant-supported partial overdentures was recorded as PAI =0.012 ± 0.022; it was PAI = 0.073 ± 0.044 for the implant-retained group. Estimated average reductions in ridge heights were 0.15 and 1.03 mm for implant-supported and implant-retained partial overdentures, respectively. Multiple linear regression models demonstrated that prosthesis type, initial mandibular ridge height, and relining frequency were significantly correlated with PAI. CONCLUSION: Implant-supported partial overdentures appear to be associated with reduced posterior mandibular alveolar ridge resorption when compared to implant-retained ones. Int J Prosthodont 2011;24:306-313.