Kerstin Gröndahl’s research while affiliated with Odontologiska Institutionen i Jönköping and other places

Background: Data on risk factors and complications after long-term implant treatment is limited. The aims were to evaluate the role of various fixation modes and to analyze complications and risks that affect long-term use of implant-supported partial fixed dental prostheses. Materials and methods: Fifty partially edentulous subjects received three Brånemark TiUnite™ implants. Superstructures were attached directly at implant level (IL) or via abutments: machined surface (AM) and an oxidized surface (AOX, TiUnite™). Implants were immediately loaded (test) or unloaded for 3 months (control). Examinations occurred over a 5-year period. Results: Forty-four subjects were re-examined after 5 years. Cumulative survival rates in test and control groups were 93.9% and 97.0%, respectively. Marginal bone loss (MBL; Mean [SEM]) was significantly lower at superstructures connected to AM (1.61 [0.25] mm) than at sites with no abutment IL (2.14 [0.17] mm). Peri-implantitis occurred in 9.1% of subjects and in 4.0% of implants. Multiple linear regression indicated that increased probing pocket depth (PPD), periodontal disease experience, deteriorating health, and light smoking (≤10 cigarettes/day) predict greater MBL, whereas increased buccal soft tissue thickness and higher ISQ predict lower MBL. Conclusions: The results show that MBL was influenced by the connection type. A machined abutment, instead of connecting the superstructure directly at the implant level, was beneficial. The following factors influenced MBL: PPD, periodontal disease experience, deteriorating health, light smoking, buccal soft tissue thickness, and ISQ. The results on peri-implantitis underscore the need for long-term maintenance care. Further, the abutment material surface properties constitute additional target for strategies to minimize MBL.

Background: Diverging opinions exist regarding rough surface abutment usage, and abutment exclusion effects are unstudied. Purpose: The study aims to: (1) assess tissue response to oxidized or machined abutments or no abutment; and (2) evaluate immediate implant-loading effects. Materials and methods: In a 2005-2008 parallel-group randomized, clinical trial, 50 partially edentulous subjects received three Brånemark TiUnite™ (Nobel Biocare®, Gothenburg, Sweden) implants. Superstructures were attached via abutments (one with a TiUnite surface - AOX, and one with a machine-milled surface - AM) or directly at implant level (IL). Implants were immediately loaded (test) or unloaded for 3 months (control). Postoperative examinations were done up to 3 years. Results: Forty-seven subjects were reexamined after 3 years. Four and two implants were lost in test and control groups, respectively, during the first year. Thereafter, no implant loss occurred (95.7% survival). After 1 year, mean (SEM) peri-implant marginal bone loss (MBL) was 1.33 (0.08) mm (test) and 1.25 (0.08) mm (control). Between 1 and 3 years, a nonsignificant MBL occurred: 0.36 (0.08) mm (test) and 0.33 (0.06) mm (control). Similar MBL was found at IL (1.81 [0.93] mm) and AOX (1.77 [0.14] mm) after 3 years and was significantly lower at AM (1.42 [0.17] mm) than at IL (groups merged); 42% of the implants displayed mucosal bleeding at 3 years and probing pocket depths varied between 2.13 (0.12) mm and 3.62 (0.15) mm, significantly lower buccally. Bleeding on probing (BoP) in minute amounts was found in 30-45% of the sites and abundant BoP at about 20% of the sites. Soft tissue retracted mostly during year 1 and was more pronounced buccally. Regression analyses revealed significant effects from smoking, periodontal disease, abundant BoP, and a low initial implant stability quotient on MBL. Conclusions: No further significant MBL was found between 1 and 3 years, irrespective of loading protocol. Use of machined abutments may benefit marginal bone stability over time.

Patients have in many studies been identified with progressive bone loss and peri-implantitis problems, but few studies are available where these groups of patients have been followed up. The purpose of this paper is to study further progression of bone loss in a cohort of 182 patients that have been reported to suffer from "progressive" bone loss and peri-implantitis. Altogether, 182 patients that have earlier been identified to suffer from "progressive" bone loss formed the present study group. Data from patients' files have been retrieved, and intraoral radiographs have been analyzed for further bone level changes. Bone loss has been measured from time of inclusion into the present group to last available radiographs. Within each patient, one or several implants were diagnosed to suffer from "progressive" bone loss (affected), whereas others are not (unaffected). Altogether, 145 patients (80%) were radiographically followed up on an average of 9.1 years (SD 3.77) after inclusion. Twenty-four implants (3.1%) were lost in 16 patients (11%). Marginal bone loss was on an average 0.3 mm (SD 0.75) at stable implants with only small differences between "affected" and "unaffected" implants. In total, 67 implants (8.6%) presented an annual bone loss of >0.2 mm. Oral hygienist treatment and/or peri-implantitis surgery did not neither reduce implant failure rate nor marginal bone loss in 88 treated patients as compared with untreated patients. Less than one-third of the patients identified with "progressive bone loss" showed one or more implants as failures or with high annual bone loss (>0.2 mm) during follow-up (11.6% of implants). Treated patients (oral hygienist and/or surgery) did not perform better than untreated patients with regard to bone loss or implant failure.

Background: Little is known about the long-term outcome of oxidized surface oral implants, especially in periodontitis-susceptible smokers. The aim of this study is to determine implant survival and marginal bone loss at turned and oxidized implants in smokers and never-smokers with periodontitis. Methods: Forty smokers and 40 never-smokers with experience of advanced periodontal disease, treated with implants 5 years previously, are included in this study. Groups were matched for sex, oral hygiene, and implant distribution, and patients were subgrouped by implant surface type (turned or oxidized). Results: The overall implant survival rate was 96.9% in never-smokers and 89.6% in smokers. Compared with oxidized implants, turned implants failed more frequently in smokers. In smokers, mean (standard error of the mean) marginal bone loss at 5 years was 1.54 (0.21) mm at turned and 1.16 (0.24) mm at oxidized implants. In never-smokers, significantly greater bone loss was found at oxidized implants, 1.26 (0.15) mm, than at turned implants, 0.84 (0.14) mm. Oxidized implants demonstrated similar bone loss for both groups. Turned implants lost significantly more bone in smokers. Compared with never-smokers, the smokers' likelihood ratio for implant failure was 4.68, 6.40 for turned and 0.00 for oxidized implants. Conclusions: The results of the study underscore the need for prevention and cessation of smoking. Turned implants failed more frequently and lost more marginal bone in smokers. In contrast, oxidized implants showed similar failure rates and bone loss in smokers and never-smokers. Turned implants displayed less bone loss than oxidized implants in never-smokers. Oxidized surface implants are more suitable for patients susceptible to periodontitis who smoke.

Purpose: To evaluate 1-year implant survival and marginal bone loss around implants that support fixed partial dentures loaded immediately or after 3 months, and effects from abutment usage. Materials and methods: In this 2005 to 2009 randomized, parallel-group, clinical trial, 50 partially edentulous patients each received three Brånemark TiUnite™ implants (Nobel Biocare®, Göteborg, Sweden), mostly in the posterior maxilla. Two implants were fitted with abutments: a TiUnite™ surface and a machine-milled surface; the suprastructure was attached directly at implant level for the third implant. After randomized allocation, implants were immediately loaded with a fixed temporary bridge (test group) or left unloaded for 3 months (control group). A permanent fixed suprastructure replaced the temporary bridge after 6 months (test). Hard and soft tissues were examined during pretreatment and surgery plus 2 days, 14 days, 4 weeks, 3 months, and 1 year after surgery. Results: After 1 year, four implants were lost in the test and two in the control groups (1-year survival rates of 94.9% [test] and 97.2% [control], with no significant intergroup difference). Resonance frequency analysis values indicated a similar pattern in both groups, with implant stability quotient (ISQ) reduction between 2 and 4 weeks. The test group had a significantly lower ISQ than the control group at these appointments. After 1 year, marginal bone losses around the implants were, on average, 1.32 mm (test, standard error of the mean [SEM] 0.08) and 1.24 mm (control, SEM 0.08), with no significant intergroup difference. Significantly larger marginal bone loss was observed at implants without abutment compared with implants with abutment. Conclusions: For both groups, this study showed similar implant survival rates and marginal bone loss. Larger bone loss was found at implants loaded without attached abutments.

Aim: To study the long-term outcome of implant survival rate, soft and hard tissue conditions and prosthetic status in a group of individuals treated with either Astra Tech TiOblast or Brånemark turned implants supporting a full-arch bridge. Material and methods: Edentulous patients treated with either Astra Tech TiOblast surface or Brånemark turned implants were recalled for examination after 12-15 years. Out of initially 66 patients 46 were available for examination. Intra-oral radiographs were taken for bone level assessments. Clinical prosthetic conditions, number of surviving implants, implant stability, plaque scores, probing pocket depths, bleeding and pus after probing were recorded. Analyses of bone level changes during the total observation period were performed. Results: Three patients in the Astra Tech group lost totally eight implants and five patients in the Brånemark group lost 10 implants during the total observation period. No statistically significant difference in implant loss or bone level change was found. Sixteen per cent of Astra Tech and 29% of Brånemark patients showed at least one implant with ≥2 mm bone loss after the first year in function. The corresponding prevalence on implant level was 6% and 5% respectively. No significant differences were found between the other examined variables. Two patients showed prosthetic complications of the supra construction in need of repair. Seven bridges had minor ceramic chippings. Conclusion: Treatment with Astra Tech TiOblast implants and Brånemark turned implants supporting full-arch bridges showed generally good clinical results with low numbers of implants with marginal bone loss indicative of peri-implantitis. No significant differences were found between the implant systems after 12-15 years in function.

Using cone beam computed tomography (CBCT) we investigated the distance between the cemento-enamel junction (CEJ) and the marginal bone crest (MBC) at buccal, lingual, mesial, and distal surfaces of incisors to first molars in adolescents before (baseline) and after extractive orthodontic treatment (study end point). Patients with Class I malocclusion, crowding and an overjet of ≤ 5 mm were examined with a CBCT unit using a 60 × 60-mm field of view and a 0.125-mm voxel size. Large differences in marginal bone height were found at baseline, particularly between tooth surfaces. There was a slight correlation between age and CEJ-MBC distance. From baseline to the study end point, large bone-height changes among teeth and tooth surfaces could be seen. Lingual surfaces, followed by buccal surfaces, showed the largest changes. Eighty-four per cent of lingual surfaces of mandibular central incisors exhibited a bone-height decrease of > 2 mm. The bone-height decrease was larger at lingual surfaces in the mandible than in the maxilla, and larger in girls (mean=1.8 mm) than in boys (mean=1.5 mm). Fewer than 1% of proximal surfaces exhibited changes of > 2 mm. It is unknown whether the changes in marginal bone height are transitory. A high-quality CBCT technique may help to determine this by providing a deeper insight into the long-term side effects of orthodontic treatment.

Diagnostics imaging is an essential component of patient selection and treatment planning in oral rehabilitation by means of osseointegrated implants. In 2002, the EAO produced and published guidelines on the use of diagnostic imaging in implant dentistry. Since that time, there have been significant developments in both the application of cone beam computed tomography as well as in the range of surgical and prosthetic applications that can potentially benefit from its use. However, medical exposure to ionizing radiation must always be justified and result in a net benefit to the patient. The as low a dose as is reasonably achievable principle must also be applied taking into account any alternative techniques that might achieve the same objectives. This paper reports on current EAO recommendations arising from a consensus meeting held at the Medical University of Warsaw (2011) to update these guidelines. Radiological considerations are detailed, including justification and optimization, with a special emphasis on the obligations that arise for those who prescribe or undertake such investigations. The paper pays special attention to clinical indications and radiographic diagnostic considerations as well as to future developments and trends.

Background: Alternative implant designs may reduce the need for complicated and costly bone augmentation procedures in situations with limited bone height. Purpose: Wide dental tube implants have been manufactured and tested in three patients and followed for 5 years to evaluate if such implants are capable to support fixed prosthetic constructions with good prognosis in areas with limited bone height. Materials and Methods: Four machined-tube implants with a height of 6 mm, an outer diameter of 7.4 mm, and an inner diameter of 6.0 mm were placed in three patients. After a healing period of 3 months, ceramometal suprastructures were constructed to supply the implants. Annual clinical and radiographical follow-ups were done up to 5 years. At the 5-year follow-up, all three patients were examined with a cone beam computed tomography technique. Results: All implants and the suprastructures were clinically stable after 5 years. In one patient, vertical bone loss and a 6-mm deep pocket appeared after 1 year. The pocket has remained throughout the observation period and has been regularly debrided and kept it free from clinical signs of inflammation. In the other two patients, the soft tissue surrounding the implants was in good health with no or only slight inflammation throughout all observations. Pocket probing revealed no or slight bleeding and pocket depths amounting to less than 3 mm. Conclusion: It was shown that this new type of implant will function excellent during follow-up times of several years. Further studies should be done to explore in more detail indications for such implants.

To investigate the incidence and severity of root resorption during orthodontic treatment by means of cone beam computed tomography (CBCT) and to explore factors affecting orthodontically induced inflammatory root resorption (OIIRR). CBCT examinations were performed on 152 patients with Class I malocclusion. All roots from incisors to first molars were assessed on two or three occasions. At treatment end, 94% of patients had ≥1 root with shortening >1 mm, and 6.6% had ≥1 tooth where it exceeded 4 mm. Among teeth, 56.3% of upper lateral incisors had root shortening >1 mm. Of upper incisors and the palatal root of upper premolars, 2.6% showed root shortenings >4 mm. Slanted surface resorptions of buccal and palatal surfaces were found in 15.1% of upper central and 11.5% of lateral incisors. Monthly root shortening was greater after 6-month control than before. Upper jaw teeth and anterior teeth were significantly associated with the degree of root shortening. Gender, root length at baseline, and treatment duration were not. Practically all patients and up to 91% of all teeth showed some degree of root shortening, but few patients and teeth had root shortenings >4 mm. Slanted root resorption was found on root surfaces that could be evaluated only by a tomographic technique. A CBCT technique can provide more valid and accurate information about root resorption.