Use of separate single-tooth implant restorations to replace two or more consecutive posterior teeth: a prospective cohort study for up to 1 year

PURPOSE

The aim of this study was to evaluate the periodontal and prosthodontic complications of multiple freestanding implants in the posterior jaws for up to 1 year of function.

MATERIALS AND METHODS

Eight patients received 20 implants posterior to canines. Two or more implants were consecutively inserted to each patient. Single crowns were delivered onto the implants. Marginal bone loss, implant mobility, probing depth, and screw loosening were examined to evaluate the clinical success of such restorations for maximum 1 year of functional loading.

RESULTS

All the implants performed well during the observation period. Neither periodontal nor prosthodontic complications were found except a slight porcelain chipping. While the marginal bone level was on average 0.09 mm lower around the implant after 6 months of loading, it was 0.15 mm higher after 1 year.

CONCLUSION

Within the limits of this investigation, separate single-tooth implant restorations to replace consecutive missing teeth may clinically function well in the posterior jaw.     

Retrospective and clinical evaluation of retrievable,tooth-implant supported zirconia-ceramic restorations

Abstract

Objective. Permanent cementations of zirconia-ceramic restorations may conflict with the rationale for retrievability of implant-supported restorations. The aim of this study was to test the hypothesis that retrievable, tooth-implant supported FDPs made of veneered zirconia ceramic cores are a viable treatment alternative. Material and methods. Restorations of patients in private practice and dental clinic were evaluated by reviewing patient records retrospectively and performing a final clinical examination. Permanently cemented copings protected the tooth abutments. The zirconia-ceramic restorations were semi-permanently cemented to the copings and the implant abutments using acrylic-urethane cement. In addition to Kaplan-Meier analyses for complications, the effect of age, gender, signs of bruxism, jaw and number of units on complications was estimated using Cox regression analyses (significance p < 0.05). Results. The follow-up period for 23 patients (nine with signs of bruxism) with four anterior and 27 posterior zirconia-ceramic restorations (3–12 units) ranged from 12.7–47.9 months. Core fractures of two posterior prostheses in patients with signs of bruxism yielded a 40-month survival rate of 93.5%. There were 10 cohesive chippings within the veneering porcelain for seven patients (six patients with signs of bruxism), which resulted in 40-month chipping rates of 5.6% among non-bruxers and 100% among patients with signs of bruxism. The hazard ratio for signs of bruxism was 20 (95% confidence interval: 2.1–188.3, p = 0.009). Conclusions. Retrievable, tooth-implant supported restorations made of zirconia-ceramics should be used with caution because of some core fractures and a considerable number of minor veneer fractures. The fracture risk was very high among patients with signs of bruxism. Due to the low number of occasions for intentional retrievals, a recommendation to use semi-permanently cemented, all-ceramic FDPs would still be premature.     

Narrow‐ and regular‐diameter implants in the posterior region of the jaws to support single crowns: A 3‐year split‐mouth randomized clinical trial

Objectives

The objective of this 3‐year split‐mouth randomized controlled clinical study was to compare narrow‐diameter implants (NDIs) to regular‐diameter implants (RDIs) in the posterior region of the jaws (premolars and molars) in regards to (i) the marginal bone level (MBL) and (ii) implant and prosthesis survival and success rates.

Material and Methods

A total of 22 patients were included in the study. Each patient received at least one implant of each diameter (Ø3.3 and Ø4.1 mm), placed either in the maxilla or mandible to support single crowns. A total 44 implants (22 NDIs and 22 RDIs) were placed and included in the study. Twenty‐one implants were placed in the premolar, whereas 23 were placed in molar areas. Radiographic evaluations to access the MBL were performed immediately after implant placement, 1 and 3 years after implant loading. Peri‐implant clinical variables including probing pocket depth (PPD) and bleeding on probing (BoP) were obtained after crown delivery, 1 and 3 years after loading. Furthermore, the survival and success rates of the implants and prosthesis were also evaluated.

Results

Twenty patients were able to complete the study. There was no statistically significant difference regarding MBL between groups at implant placement (p = .084), 1‐year (p = .794) and 3‐year (p = .598) time intervals. The mean peri‐implant bone loss at 3‐year follow‐up was ?0.58 ± 0.39 mm (95% CI: ?0.751 to ?0.409) and ?0.53 ± 0.46 mm (95% CI: ?0.731 to ?0.329) for NDIs and RDIs, respectively. BoP was present at 15% and 10% of NDIs and RDIs, respectively, at 3‐year follow‐up. PPD >5 mm was observed in 5% and 0% of the implants of NDIs and RDIs, respectively, at 3‐year follow‐up. At the 3‐year examination, the implant success rates were in the NDIs and RDIs sites, respectively, 95% and 100%. The corresponding values for prosthesis success rates were 90% for NDIs and 95% for RDIs.

Conclusion

The present study demonstrated that NDIs placed to support single crowns in the posterior region did not differ to RDIs in regards to MBL, implant survival, and success rates.     

Complication rate of molar crowns: a practice-based clinical evaluation

This practice-based study evaluates the initial clinical performance of conventionally luted metal-ceramic and zirconia molar crowns fabricated with a prolonged cooling period of the veneering porcelain. Forty-nine patients were treated (group A: high precious alloy + low fusing porcelain; group B: zirconia crowns). All zirconia crowns were veneered with a modified porcelain firing cycle including a 6-minute cooling period. Ninety-two restorations (74 vital abutments/18 nonvital abutments) were evaluated after a mean observation period of 18.2 +/- 4.6 months. No complete failures or loss of vitality were recorded in either group. Two events were recorded in group A (1 loss of retention/1 minor ceramic chipping < 2 mm2). The third event occurred in group B (minor ceramic chipping <2 mm2). All ceramic defects could be polished intraorally. Statistical analysis revealed non-significant differences in success rates (p = 0.91) of metal-ceramic and zirconia crowns fabricated with a modified porcelain firing. The modified firing of the zirconia porcelain seems to decrease the risk for early ceramic chipping in the molar area, leading to a technical complication rate comparable to that of metal-ceramic crowns.     

Dental implant treatment for two adjacent missing teeth in the maxillary aesthetic zone: a comparative pilot study and test of principle

Aim: The aim of this prospective comparative pilot study was to evaluate hard and soft peri‐implant tissues in patients with a missing adjacent central and lateral upper incisor treated with either one implant and an implant crown with a cantilever or two implants with solitary implant crowns up to 1 year after functional loading. Material and methods: In the “Implant–cantilever group”, five patients were treated with one dental implant in the region of the central incisor (NobelReplace Groovy Regular Platform). In the “Implant–implant group”, five patients were treated with two adjacent dental implants: at the position of the central incisor (NobelReplace Groovy Regular Platform) and at the position of the lateral incisor (NobelReplace Groovy Narrow Platform). Implant survival, pocket probing depth, papilla index, marginal bone level and patient satisfaction were assessed during a 1‐year follow‐up period. Results: No implants were lost during the 1‐year follow‐up. Mean pocket probing values of the implants were comparable between the two groups. Papilla index scores in both groups were relatively low, pointing towards a compromised papilla. Marginal bone loss was minimal and comparable between the groups. Patient satisfaction was very high in both groups. Conclusion: In this 1‐year prospective comparative study, no large differences in hard‐ and soft‐tissue levels could be shown between patients with a missing central and lateral upper incisor treated with either one implant and an implant crown with a cantilever or two implants with solitary implant crowns. To cite this article:
Tymstra N, Raghoebar GM, Vissink A, Meijer HJA. Dental implant treatment for two adjacent missing teeth in the maxillary aesthetic zone: a comparative pilot study and test of principle.
Clin. Oral Impl. Res. 22 , 2011; 207–213.
doi: 10.1111/j.1600‐0501.2010.02017.x     

Cemented CeraOne and porcelain fused to TiAdapt abutment single-implant crown restorations: a 10-year comparative follow-up study

Background: Long‐term data comparing cemented and noncemented single‐implant restorations has not been reported. Aim: To compare clinical and radiographic performance of single‐implant crown restorations made by either directly baked porcelain to custom‐made TiAdapt? titanium abutments (Nobel Biocare AB, Göteborg, Sweden) (test) or cement crowns onto CeraOne® (Nobel Biocare AB) abutments (control) after 10 years in function. Materials and Methods: Altogether, 35 consecutive patients were provided with 41 turned single Brånemark System® implants (Nobel Biocare AB) in the partially edentulous upper jaw. By random, 15 and 20 patients were provided with 18 test and 23 control implant crowns, respectively. Thereafter, clinical and radiographic data were collected and compared between the two groups. Results: None of the implants were found loose during the follow‐up period (100%). Few clinical problems were observed, and the overall average marginal bone loss was 0.26 mm (SD 0.64) during 10 years in function. After the final tightening of the crowns, no significant differences were observed between the test and control groups (p > .05). The head of the implants was placed on an average 6.3 mm (SD 2.24) below the cement/enamel junction of the adjacent teeth (range 2.5–10.0 mm). Implants with reported mechanical and/or mucosal problems or placed more apically in relation to the adjacent teeth did not present more bone loss as compared with implants with no problems or placed more coronally, respectively (p > .05). Conclusions: There seems to be no obvious clinical or radiographic differences between the test and control single‐implant restorations during 10 years of follow‐up. Occasionally, some restorations presented loose abutment screws and/or fistulas during follow‐up. This implies a certain need for maintenance where a one‐piece single‐implant protocol (test) allows both for a simple clinical procedure at placement without cementation problems, as well as for an easy and simple maintenance of installed single implant crowns in long‐term function.     

Laser-welded titanium frameworks supported by implants in the partially edentulous mandible: a 10-year comparative follow-up study

Background: Comparative long‐term knowledge of different framework materials in the partially edentulous implant patient is not available. Purpose: To report and compare 10‐year data on free‐standing implant‐supported partial prostheses with laser‐welded titanium (test) and conventional gold alloy (control) frameworks. Materials and Methods: Altogether, 52 partially edentulous patients were consecutively provided with laser‐welded prostheses (n = 60) in the partially edentulous lower jaw (test group). A control group of 52 randomly selected patients with gold alloy castings (n = 60) was used for comparison. Clinical and radiographic 10‐year data were retrospectively collected and evaluated for both groups. Results: The overall 10‐year implant cumulative survival rate (CSR) was 93.0% (loaded implants, 96.4%), with a 10‐year implant CSR of 91.5 and 94.7% for test and control implants, respectively (p > .05). Out of a total of 22 lost implants, 17 implants (77.3%) were shorter than 10 mm. The overall 10‐year prosthesis CSR was 93.7%, with a corresponding 10‐year CSR of 88.4 and 100% for test and control groups, respectively (p < .05). Average 10‐year bone loss was 0.46 mm (SD 0.47) and 0.69 mm (SD 0.53) for the test and control groups (p < .001), respectively. Only 1% of the implants had >3 mm accumulated bone loss after 10 years. Altogether, 10 of the prostheses in both groups had implant component mechanical problems (8.3%). None of the frameworks or implants fractured, but more fractures of porcelain veneers were observed in the test group (p < .05). Conclusion: The protocol of implant treatment in the partially edentulous jaw functioned well during 10 years, although prosthodontic maintenance was required. However, laser‐welded titanium frameworks presented more problems as compared with gold alloy frameworks. More loaded implants were lost (p < .05), and higher incidence of porcelain chipping was noted in the test group (p < .05). However, bone loss was on an average lower for the test group during the 10 years of follow‐up (p < .001).     

Single Implant Treatment in Healing versus Healed Sites of the Anterior Maxilla: A Clinical and Radiographic Evaluation

Purpose: The aim was to document the Nobelreplace tapered TiUnite® (Nobel Biocare, Göteborg, Sweden) implant system used by experienced clinicians in daily practice for replacing single maxillary anterior teeth and to compare the clinical and radiographic outcome between implants installed in healing sites (early implant placement) and fully healed sites (conventional implant placement) after on average two and a half years of function. Material and Methods: A cross‐sectional study in patients who had been treated by two periodontists and two prosthodontists in 2006 and 2007 was conducted. Surgical treatment involved standard flap elevation without releasing incisions and restorative procedures included cemented crowns in all patients. Only straightforward single implant treatments in healing sites (6–8 weeks following tooth extraction) and fully‐healed sites (≥6 months following tooth extraction) were considered with both neighboring teeth present and without the need for hard and/or soft tissue grafting. Clinical and radiographic analyses of all implants were performed by a blinded clinician who had not been involved in the treatment. Results: Forty‐nine of the 53 eligible single implants (22 early and 27 conventionally placed implants) in 44/48 patients were available for scrutiny. There was no significant difference in implant survival between early (95%) and conventionally (93%) installed implants (p = 1.000). Mean bone level to the implant‐abutment interface was 1.25 and 1.02 mm for early and conventional implant placement, respectively (p = .220). In spite of fairly low plaque levels (26%), overall peri‐implant bleeding was quite prevalent (36%). Mean peri‐implant probing depth was 3.3 mm. Five restorations had experienced technical complications. Conclusions: Single Nobelreplace tapered TiUnite® implants installed in healing as well as in healed sites of the anterior maxilla are predictable. Both strategies seem equally successful in terms of implant survival, bone remodeling, clinical response, and risk for complications.     

Zirconia for teeth and implants: a case series

This case series reports on the use of nonsilica-based high-strength full ceramics for different prosthetic indications. Fifty-two consecutive patients received tooth- or implant-supported zirconia reconstructions during a 2-year period. The observation period for reexamination was 12 to 30 months. The most frequent indications were single crowns and short-span fixed partial dentures. A few implant superstructures were screw-retained, whereas all remaining restorations were cemented on natural teeth or zirconia implant abutments. Clinical examination included biologic (probing depths, bleeding on probing) and esthetic (Papilla Index) parameters, as well as technical complications. No implant was lost or caused any problems, but two teeth were lost after horizontal fracture. Overall, the periodontal parameters were favorable. Fractures of frameworks or implant abutments were not observed. Abutment-screw loosening occurred once for one premolar single crown. Furthermore, five implant crowns in the posterior region exhibited chipping of the porcelain veneering material. With regard to esthetics, no reconstructions were considered unacceptable, but three crowns were remade shortly after delivery. In this short-term study, it was observed that biologic, esthetic, and mechanical properties of zirconia were favorable, and the material could be used in various prosthetic indications on teeth or implants.     

An in vivo comparison of internal bacterial colonization in two dental implant systems: Identification of a pathogenic reservoir

Abstract

Objectives. The aim of this study was to compare internal bacterial colonization in two implant systems, one screw root form (SRF) with an external hexagon connection and one plateau root form (PRF) with a Morse taper internal connection. Materials and methods. Thirty-two implants; 12 SRF and 20 PRF, were sampled in 15 patients. All implants had been in function for at least 6 months prior to sampling. The implant restoration was removed and 10 µl of sterile saline was introduced into the implant well via a sterile glass syringe. The saline was drawn back up and transferred to the laboratory for microbiological analysis. The number of aerobic and anaerobic colony forming units per millilitre was determined and the dominant micro-organism in each sample was identified by 16s rRNA gene amplicon sequencing. Results. There was a significant difference between bleeding on probing around the SRF implants (3%) and the PRF implants (28%) (p = 0.0496). Bacterial colonization was identified at 11 SRF and 19 PRF implants. The numbers of anaerobic bacteria recovered from PRF implants was significantly higher than that from SRF implants (p = 0.0002). Streptococcus species and Enterococcus faecalis were found to dominate. Conclusions. This in vivo study demonstrated bacterial colonization in both types of implant systems, irrespective of the type of connection. Significantly greater anaerobic counts were found in the Morse taper internal connection implants.     

Maxillary Overdentures Supported by Anteriorly or Posteriorly Placed Implants Opposed by a Natural Dentition in the Mandible: A 1‐Year Prospective Case Series Study

Background: For maxillary overdenture therapy, treatment guidelines are missing. There is a need for longitudinal studies. Purpose: The purpose of this 1‐year prospective case series study was to assess the treatment outcome of maxillary overdentures supported by six dental implants opposed by natural antagonistic teeth in the mandible. Materials and Methods: Fifty patients were treated with a maxillary overdenture supported by six dental implants, either placed in the anterior region (n = 25 patients) or in the posterior region (n = 25 patients). Items of evaluation were the following: survival of implants, condition of hard and soft peri‐implant tissues, and patients' satisfaction. Results: One‐year implant survival rate was 98% in the anterior group and 99.3% in the posterior group. Mean radiographic bone loss in the anterior and posterior groups after 1 year of loading was 0.22 and 0.50 mm, respectively. Mean scores for plaque, calculus, gingiva, bleeding, and pocket probing depth were low, and patients' satisfaction was high, with no differences between the groups. Conclusion: Six dental implants placed in either the anterior region or the posterior region of the edentulous maxilla, connected with a bar, and opposed by antagonistic teeth in the mandible supply a proper base for the support of an overdenture.     

Associations of alveolar bone loss and interleukin-1β levels in one- and two-stage surgical procedures: a randomized prospective trial

Objective: Dental implants have been widely and successfully used in recent years as an alternative treatment for removable and fixed dental prostheses. The aim of this randomized prospective study was to determine the alveolar bone loss rate (ABLR) and IL-1β levels in one- and two-stage surgical procedures.

Materials and methods: This study included 40 patients with a single missing tooth in the posterior mandible; dental implants were inserted using a one-stage surgical procedure (Group I) or a two-stage surgical procedure (Group II). All clinical periodontal parameters were recorded; peri-implant crevicular fluid (PICF) samples were collected before loading (T0) and during the third (T1) and sixth (T2) months after loading. ABLR values were evaluated at T0 and T2 by using dental tomography. PICF was analysed after T2 samples were collected. The study was registered through clinicaltrials.gov; identifier NCT03045458.

Results: This study found that, the probing pocket depth was found to be significantly higher in Group I than Group II at both T1 and T2 (p?p?>?.05). There was a significant difference between Group I ABLR values at T0 and T2 (p?p?>?.05).

Conclusions: Within the limitations of the short observational period and small sample size of this study, two-stage implant placement shows comparable clinical outcomes to implants placed using a one-stage placement protocol.     

Impact of Platform Switching on Peri‐Implant Bone Remodeling around Short Implants in the Posterior Region, 1‐Year Results from a Split‐Mouth Clinical Trial

Aim: To assess the effect of platform switching on peri‐implant bone remodeling around short implants (8.5 mm) placed in the resorbed posterior mandibular and maxillary region of partially edentulous patients. Materials and Methods: Seventeen patients with one or more missing teeth at both sides in the posterior region were, according to a split‐mouth design, randomly assigned to be treated with a platform‐matched (control) implant on the one side and a platform‐switched implant (test) on the other side. A total of 62 short implants (8.5 mm) with a dual‐acid etched surface with nanometer‐sized calcium phosphate particles was placed. Follow‐up visits were conducted one month and one year after placing the implant crown. Outcome measures were interproximal bone level changes, implant survival and clinical parameters. Results: One year after loading, peri‐implant bone remodeling around test implants (0.53 ± 0.54 mm) was significant less than around control implants (0.85 ± 0.65 mm; p = .003). With regard to implant survival and clinical parameters no significant differences were observed between test and control implants. Conclusions: This study suggested that peri‐implant bone remodeling is affected by platform switching. One year after loading, interproximal bone levels were better maintained at implants restored according to the platform switching concept.     

Marginal Bone Level Changes and Prosthetic Maintenance of Mandibular Overdentures Supported by 2 Implants: A 5‐Year Randomized Clinical Trial

Background: Documentation of early loading of mandibular overdentures supported by different implant systems is scarce. Purpose: This study aimed to compare the biologic and prosthetic outcome of mandibular overdentures supported by unsplinted early‐loaded one‐ and two‐stage oral implants after 5 years of function. Materials and Methods: Twenty‐eight consecutive patients were screened following an inclusion and exclusion criteria, and randomly allocated to treatment groups. Ball‐retained mandibular overdentures were fabricated on two unsplinted Straumann® (Institut Straumann AG, Basel, Switzerland) and Brånemark® (Nobel Biocare AB, Göteborg, Sweden) dental implants and subjected to an early‐loading protocol. During the 5‐year period, prosthetic complications were recorded. At 5‐years of function, plaque, peri‐implant inflammation, bleeding, and calculus index scores were recorded, and standard periapical radiographs were obtained from each implant for measurement of marginal bone loss. Results: All implants survived during the observation period. The peri‐implant inflammation, bleeding, and calculus index scores around Straumann and Brånemark implants were similar (p > .05). The marginal bone loss around Brånemark implants (1.21 ± 0.1) was higher than Straumann implants (0.73 ± 0.06) at 5 years of function (p = .002). Kaplan–Meier tests revealed that 1‐ and 5‐year survival of overdentures on Straumann and Brånemark implants were similar (p = .85). Wear of the ball abutment in the Brånemark group was higher than in the Straumann group (p < .05). Complications regarding the retainer and the need for occlusal adjustments were higher in the Straumann group (p < .05). Chi‐square test revealed that the frequency of retightening of the retainer was higher in the Straumann group than in the Brånemark group (p < .05). Conclusions: Mandibular overdentures supported by unsplinted early‐loaded Straumann and Brånemark implants lead to similar peri‐implant soft tissue and prosthetic outcomes, although higher marginal bone loss could be observed around Brånemark implants after 5 years.     

The effect of subcrestal placement of the polished surface of ITI® implants on marginal soft and hard tissues

In order to achieve esthetically more satisfying results, it has been proposed to place ITI implants with their border between the rough and smooth surfaces below the level of the alveolar crest, thereby obtaining a submucosally located implant shoulder following healing. The aim of the present experimental study was to clinically and radiographically evaluate the tissue response to the placement of one-stage transmucosal implants with the border between the rough and the smooth surfaces sunk by 1mm into a subcrestal location. 11 patients underwent comprehensive dental care including the placement of 2 implants of the ITI Dental Implant SystemTM in the same quadrant (test and control). Randomly assigned control implants were placed according to the manufacturer's instructions, i.e. the border between the rough titanium plasma-sprayed and the smooth polished surfaces precisely at the alveolar crest. At the test implants the apical border of the polished surface was placed ?1mm below the alveolar crest. Probing bone levels were assessed at implant placement (baseline), 4 and 12 months later. Modified plaque and modified gingival indices were recorded at 1, 2, 3,4 and 12 months. Clinical probing depth and “attachment” levels were measured at 4 and 12 months. All parameters were assessed at 6 sites around each implant. The mean for each implant was calculated and used for analysis. The Wilcoxon matched pairs signed rank test and the Student r-test were applied to detect differences over time and between the test and control implants. At baseline, a mean difference in probing bone level of ?0.86mm (SD 0.43 mm, p<0.05) was found between test and control implants with the test implants being placed more deeply. Both test and control implants lost a significant amount of clinical bone height during the first 4 months (test 1.16mm, p<0.05: control 0.58 mm. p<0.05). However, only the test implants significantly lost clinical bone height from 4–12 months (test 1.04 mm, p<0.05; control 0.45mm, p=0.08). Overall, the test implants lost 2.26mm and the control implants 1.02mm of bone height during the first year of service. On the average, the test implants demonstrated a bone level 0.38mm lower than the controls at 12 months. Except for the modified gingival index at 4 months (mean difference 0.21, SD 0.19, p<0.05), no clinical parameters yielded significant differences between test and control implants at any time. It is concluded that in addition to the crestal bone resorption occurring at 1 implants placed under standard conditions, the bone adjacent to the polished surface of 1 more deeply placed ITI implants is also lost over time. Form a biological point of view, the placement of the border between the rough and the smooth surfaces into a subcrestal location should not be recommended.     

Clinical and radiographic performance of delayed-immediate single-tooth implant placement associated with peri-implant bone defects. A 2-year prospective, controlled, randomized follow-up report

Objectives: The aim of the present study was to compare the delayed‐immediate (Im) and the delayed (De) protocols for placement of single‐tooth implants. Material and methods: After allocation to the Im and De groups by random, 46 patients were treated with a single‐tooth implant with acid etched surfaces (Osseotite^®) in the anterior or pre‐molar region of the maxilla or the mandible on average 10 days (Im) or 3 months (De) following tooth extraction, respectively. Forty‐one patients attended a follow‐up visit 2 years after implant placement corresponding to 1½ years of loading of the implant restorations. Peri‐implant and prosthetic parameters were evaluated clinically and marginal bone levels measured on radiographs. Results: Three implants were lost, all before mounting of the crown. None of the implant restorations had failed after 1½ years of function. Probing pocket depths were reduced by up to 1.4 mm on average from the time of loading to the 2‐year follow‐up and at that time, no significant difference between the Im and De groups was found (4.2 versus 4.1 mm). A statistically significant radiographic marginal bone loss had occurred in the Im group (mean=0.8 mm) as well as in the De group (mean=0.7 mm) in the follow‐up period. However, a mean marginal bone level of approx. 1.5 mm in both groups measured from the implant–abutment junction was found to be acceptable. It was demonstrated that probing pocket depths and marginal bone levels after 1½ years of loading of the implant‐retained crowns were not influenced by the presence of peri‐implant bone defects immediately after implant placement. Furthermore, no severe prosthodontic complications, such as screw loosening or porcelain fractures, arose in this study material. Conclusion: High success rates of single‐tooth implants after 1½ years of function were achieved using the delayed‐immediate and delayed implant placement techniques.     

Analysis of load transfer and stress distribution by splinted and unsplinted implant‐supported fixed cemented restorations

Summary Controversy remains over the rehabilitation of implant‐supported restorations regarding the need to splint adjacent implant‐supported crowns. This study compared the effects of simulated occlusal loading of three implants restored with cemented crowns, splinted versus unsplinted. Three adjacent screw‐shaped implants were passively inserted into three holes drilled in a photo‐elastic model. Two combinations of cemented restorations were fabricated; three adjacent unsplinted and three adjacent splinted crowns. Strain gauges were connected to the implant necks and to the margins of the overlaying crowns. Fifteen axial static loads of 20‐kg loadings were carried out right after each other via a custom‐built loading apparatus. Strain gauges located on the implant neck supporting splinted restoration demonstrated significantly (P < 0·001) more strain (sum of strains = 3348·54 microstrain) compared with the single crowns (sum of strains = 988·57 microstrain). In contrast, significantly (P < 0·001) more strain was recorded on the strain gauges located on the restoration margins of the single crowns (sum of strains = 756·32 microstrain) when compared with splinted restorations (sum of strains = 186·12 microstrain). The concept of splinting adjacent implants to decrease loading of the supporting structures may require re‐evaluation. The clinical relevance of these findings needs further investigation.     

Complications in partially edentulous implant patients: a 5-year retrospective follow-up study of 133 patients supplied with unilateral maxillary prostheses

Background: Numerous studies have reported successful outcomes for restoration of fully endentulous patients with Brånemark implants. However, some studies indicate more mechanical problems in restored partially endentulous situations. Purpose: The objective was to study patients with potential risk for mechanical complications after implant treatment. Materials and Methods: Patients were retrospectively evaluated 5 years after implant treatment in upper jaw Appelgate-Kennedy Class II situations. Altogether 422 implants ad modum Brånemark were installed in 137 consecutively treated patients. One hundred thirty-three prostheses were placed and followed-up for 5 years, according to routine clinical protocols. Results: The overall 5-year implant cumulative survival rate (CSR) was 94.0%. The corresponding CSR for loaded implants and prostheses was 97.7% and 98.4%, respectively, and the overall marginal bone loss was 0.8 mm (0.6 mm) after 5 years. Sixteen abutment screws fractured in seven patients (5%) and 17 prostheses (13%) presented loose abutment or gold screws during the follow-up period. Significantly more problems were reported in association with prostheses that included the canine (p <.05), and significantly more gold screws were working loose when only two implants were supporting the frameworks (p<.01). Conclusions: Upper jaw implant treatment in unilateral free-end situations seems to involve more mechanical problems than other implant treatment groups when only two implants can be installed and when the canine tooth is missing. However, most of these complications are easily adjusted, and the clinical survival of implants and prostheses is the same for these groups compared to other groups of partially edentulous implant patients.     

Immediate loading of mandibular overdentures supported by unsplinted direct laser metal-forming implants: results from a 1-year prospective study

Background: At present, only some studies have dealt with immediate loading of unsplinted implants supporting mandibular overdentures. The aim of this prospective study is to evaluate treatment outcomes of mandibular overdentures supported by four one‐piece, unsplinted, immediately loaded, direct laser metal‐forming (DLMF) implants by assessing implant survival rate, implant success, marginal bone loss, and prosthetic complications. Methods: A total of 96 one‐piece DLMF implants were inserted in the edentulous mandible of 24 patients. Four implants were placed in each edentulous mandible. Immediately after implant placement, a mandibular overdenture was connected to the implants. At 1‐year follow‐up, clinical, radiographic, and prosthetic parameters were assessed. Success criteria included absence of pain, suppuration, and implant mobility; absence of continuous peri‐implant radiolucency; and distance between the implant shoulder and the first visible bone contact <1.5 mm. Results: After a 1‐year loading time, the overall implant survival rate was 98.9%, with only one implant lost. Among the surviving 95 implants, two did not fulfill the success criteria; therefore, the implant success rate was 97.8%. The mean distance between the implant shoulder and the first visible bone contact was 0.28 ± 0.30 mm (95% confidence interval, 0.24 to 0.32). Some prosthetic complications were reported. Conclusion: Based on the present results and within the limits of this study, the immediate loading of four unsplinted DLMF implants by means of ball attachment–supported mandibular overdentures seems to represent a safe and successful procedure.     

One-Year Prospective Evaluation of the Early Loading of Unsplinted Conical Brånemark Fixtures with Mandibular Overdentures Immediately following Surgery

Background: Prospective evaluation of the early loading of unsplinted Branemark implants with mandibular over‐dentures opposing conventional dentures is not evident in the implant‐related literature. Purpose: To clinically evaluate progressive and early loading of 20 unsplinted conical Brånemark implants in edentulous mandibles with overdentures. Materials and Methods: Ten edentulous patients all had two conical Brånemark implants placed in the anterior mandible with mandatory primary stability with bicortical anchorage. Ball abutment connection was performed simultaneously. Previously constructed conventional mandibular dentures were temporarily relined with tissue conditioner postoperatively and worn with moderation for the first 2 weeks to allow progressive loading. Early loading of the implants followed after 2 weeks, with inclusion of the respective matrices in the mandibular dentures, using a definitive reline procedure. Results: All patients successfully functioned with their mandibular implant overdentures from 2 to 52 weeks postoperatively. Mean marginal bone loss was within established criteria for success:0.22 mm (SD = 0.48 mm) mesially and 0.30 mm (SD = 0.39 mm) distally on the conical implants. Mobility tests using the Periotest instrument became more negative, although not at statistically significant levels. Difficulties in the management of the peri‐implant mucosa between surgery and loading at 2 weeks were observed in 40% of the patients. Conclusions: These preliminary 1‐year results show that successful early loading of unsplinted conical Brånemark implants with mandibular overdentures is possible.