Volumetric osseous changes in the completely edentulous maxilla after sinus grafting and lateral bone augmentation: a systematic review

The aim of this systematic review was to evaluate the volumetric changes associated with different bone grafting techniques in the completely edentulous atrophic maxilla before dental implant placement. A search was performed according to the PRISMA guidelines. A PICO question was formed, and the PubMed, Scopus, Embase, and Cochrane Library databases were searched, covering the period 2000-2018. Relevant data were extracted from the results regarding study population, surgical details, technical information on volumetric data acquirement, and volumetric outcome after bone augmentation procedures before implant placement. Six articles with a combined population of 84 patients were included. All patients had a completely edentulous maxilla, with a crestal horizontal width of <3-4mm or a crestal vertical height of <6-7mm. The iliac bone and ascending ramus were most frequently used as grafts. Five of the six studies reported volumes of sinus inlay graft (SIG) and four reported volumes of lateral bone augmentation (LBA). Radiographic analyses of the augmented areas differed among the studies. Volume loss after bone augmentation procedures ranged from 5% to 50% for SIG and from 5% to 47% for LBA. All surgical augmentation techniques for the edentulous maxilla are prone to resorption; no procedure seemed to be superior, but some interesting observations were made.

Surgical removal versus retention for the management of asymptomatic disease-free impacted wisdom teeth

BACKGROUND

Prophylactic removal of asymptomatic disease-free impacted wisdom teeth is surgical removal of wisdom teeth in the absence of symptoms and with no evidence of local disease. Impacted wisdom teeth may be associated with pathological changes, such as pericoronitis, root resorption, gum and alveolar bone disease (periodontitis), caries and the development of cysts and tumours. When surgical removal is carried out in older people, the risk of postoperative complications, pain and discomfort is increased. Other reasons to justify prophylactic removal of asymptomatic disease-free impacted third molars have included preventing late lower incisor crowding, preventing damage to adjacent structures such as the second molar or the inferior alveolar nerve, in preparation for orthognathic surgery, in preparation for radiotherapy or during procedures to treat people with trauma to the affected area. Removal of asymptomatic disease-free wisdom teeth is a common procedure, and researchers must determine whether evidence supports this practice. This review is an update of an existing review published in 2012.

OBJECTIVES

To evaluate the effects of removal compared with retention (conservative management) of asymptomatic disease-free impacted wisdom teeth in adolescents and adults.

SEARCH METHODS

We searched the following electronic databases: Cochrane Oral Health's Trials Register (to 24 May 2016), the Cochrane Central Register of Controlled Trials (CENTRAL) (2016, Issue 4), MEDLINE Ovid (1946 to 24 May 2016) and Embase Ovid (1980 to 24 May 2016). We searched ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform for ongoing and unpublished studies to 24 May 2016. We imposed no restrictions on language or date of publication in our search of electronic databases.

SELECTION CRITERIA

Studies comparing removal (or absence) with retention (or presence) of asymptomatic disease-free impacted wisdom teeth in adolescents or adults. We included randomised controlled trials (RCTs) with no restriction on length of follow-up, if available. We considered quasi-RCTs and prospective cohort studies for inclusion if investigators measured outcomes with follow-up of five years or longer.

DATA COLLECTION AND ANALYSIS

Eight review authors screened search results and assessed the eligibility of studies for inclusion according to the review inclusion criteria. Eight review authors independently conducted risk of bias assessments in duplicate. When information was unclear, we contacted study authors for additional information.

MAIN RESULTS

This review includes two studies. The previous review included one RCT with a parallel-group design, which was conducted in a dental hospital setting in the United Kingdom; our new search for this update identified one prospective cohort study conducted in the private sector in the USA. Primary outcome No eligible studies in this review reported the effects of removal compared with retention of asymptomatic disease-free impacted wisdom teeth on health-related quality of life Secondary outcomes We found only low to very low quality evidence of the effects of removal compared with retention of asymptomatic disease-free impacted wisdom teeth for a limited number of secondary outcome measures.One prospective cohort study, reporting data from a subgroup of 416 healthy male participants, aged 24 to 84 years, compared the effect of the absence (previous removal or agenesis) against the presence of asymptomatic disease-free impacted wisdom teeth on periodontitis and caries associated with the distal of the adjacent second molar during a follow-up period of three to over 25 years. Very low quality evidence suggests that the presence of asymptomatic disease-free impacted wisdom teeth may be associated with increased risk of periodontitis affecting the adjacent second molar in the long term. In the same study, which is at serious risk of bias, there is insufficient evidence to demonstrate a difference in caries risk associated with the presence or absence of impacted wisdom teeth.One RCT with 164 randomised and 77 analysed adolescent participants compared the effect of extraction with retention of asymptomatic disease-free impacted wisdom teeth on dimensional changes in the dental arch after five years. Participants (55% female) had previously undergone orthodontic treatment and had 'crowded' wisdom teeth. No evidence from this study, which was at high risk of bias, was found to suggest that removal of asymptomatic disease-free impacted wisdom teeth has a clinically significant effect on dimensional changes in the dental arch.The included studies did not measure our other secondary outcomes: costs, other adverse events associated with retention of asymptomatic disease-free impacted wisdom teeth (pericoronitis, root resorption, cyst formation, tumour formation, inflammation/infection) and adverse effects associated with their removal (alveolar osteitis/postoperative infection, nerve injury, damage to adjacent teeth during surgery, bleeding, osteonecrosis related to medication/radiotherapy, inflammation/infection).

AUTHORS' CONCLUSIONS

Insufficient evidence is available to determine whether or not asymptomatic disease-free impacted wisdom teeth should be removed. Although asymptomatic disease-free impacted wisdom teeth may be associated with increased risk of periodontitis affecting adjacent second molars in the long term, the evidence is of very low quality. Well-designed RCTs investigating long-term and rare effects of retention and removal of asymptomatic disease-free impacted wisdom teeth, in a representative group of individuals, are unlikely to be feasible. In their continuing absence, high quality, long-term prospective cohort studies may provide valuable evidence in the future. Given the lack of available evidence, patient values should be considered and clinical expertise used to guide shared decision making with patients who have asymptomatic disease-free impacted wisdom teeth. If the decision is made to retain asymptomatic disease-free impacted wisdom teeth, clinical assessment at regular intervals to prevent undesirable outcomes is advisable.

A randomized clinical trial of biodegradable and titanium fixation systems in maxillofacial surgery

Biodegradable fixation systems could reduce or delete the problems associated with metallic systems, since removal is not necessary. The aim of this study was to establish the effectiveness and safety of biodegradable plates and screws as potential alternatives to metallic ones. This multi-center randomized controlled trial was conducted from December 2006 to July 2009. Included were patients who underwent mandibular and/or Le Fort I osteotomies and those with fractures of the mandible, maxilla, and zygoma. The patients were assigned to a titanium control group (KLS Martin) or to a biodegradable test group (Inion CPS). The primary outcome measure was 'bone healing 8 weeks post-operatively'. The Intention-To-Treat (ITT) analysis of 113 patients in the titanium group and 117 patients in the biodegradable group yielded a significant difference (p < 0.001), primarily because in 25 patients (21%) who were randomized to the biodegradable group, the surgeon made the decision to switch to titanium intra-operatively. Despite this 'inferior' primary outcome result, biodegradable plates and screws could be safely used when it was possible to apply them. The benefits of using biodegradable systems (fewer plate removal operations) should be confirmed during a follow-up of minimally 5 years (Controlled-trials.com ISRCTN number 44212338).

Stabilisation of sagittal split set-back osteotomies with miniplates: a prospective, multicentre study with 2-year follow-up

The aim of this study was to assess post-operative stability of bilateral sagittal split set-back osteotomies using two miniplates and clinical parameters including nerve function, TMJ function, occlusal relapse and patient satisfaction. The stability was measured on cephalometric radiographs and possible condylar alterations on orthopantomograms. This prospective study implied a 2-year follow-up on a group of 24 patients. The same protocol was used at six participating institutions at which the patients were treated. A stable occlusion without appreciable relapse was seen in 91% after 2-year follow-up. Only two patients in this study had mild occlusal relapse. The mean skeletal horizontal relapse at pogonion of the whole group, after 2 years was 1.1mm and appeared to be directed backwards. At occlusal level, however, the mean relapse was 1.2mm forwards. The function of the inferior alveolar nerve 2 years post-operatively was reported to be normal in approximately 70% of the patients, yet 80% had no complaints about nerve dysaesthesia. In approximately 21% of the patients, signs and symptoms of TMJ dysfunction had disappeared. Another group (10%), however, without pre-operative signs and symptoms of TMJ dysfunction developed these signs or symptoms post-operatively. No condylar remodelling or resorption was seen in this group of patients. The sagittal split set-back osteotomy fixed with miniplates appeared to be a relatively save and reliable procedure giving rise to adequate results and a high degree of patients satisfaction.

Stabilisation of sagittal split advancement osteotomies with miniplates: a prospective, multicentre study with two-year follow-up. Part II. Radiographic parameters

This prospective study implied a two-year follow-up on a group of patients that underwent a Bilateral Sagittal Split Osteotomy (BSSO) for advancement (n=222) of the mandible that were treated in seven institutions following the same treatment protocol. The aim of Part II of this study was to correlate the clinical findings on stability and relapse as reported in Part I (clinical parameters) of this series of articles with the cephalometric findings. The mean skeletal relapse at pogonion of the whole group after two years was 0.9 mm. The clinically stable group, however, had only 0.4 mm relapse, whereas the clinical relapse group showed a mean relapse of 3.3 mm. The findings underline a relationship between the amount of advancement and relapse. The tendency for both, horizontal and vertical movement is the same, i.e., the larger the surgery effect, the larger the relapse. The angle post plane/mandibular plane showed the highest explained variance 9%. Patients with a high mandibular plane angle may be more prone to relapse. The explained variance of all considered prognostic factors together, however, is small (13%). The findings of this study express that patients with a clinical stable occlusion after a BSSO advancement, stabilised with miniplates, have a minimal to no skeletal relapse as measured on the cephalometric radiograms. The clinically non-stable group, however, appeared to have considerable skeletal relapse.

Stabilisation of sagittal split advancement osteotomies with miniplates: a prospective, multicentre study with two-year follow-up

This prospective study implied a two-year follow-up in a group of patients that underwent a Bilateral Sagittal Split Osteotomy (BSSO) for advancement of the mandible that were treated in seven institutions following the same treatment protocol (using two miniplates). The aim of Part III of this study was to define a Condylar Morphology Scale (CMS) and to analyse radiological changes in the TMJ after BSSO in relation to postoperative relapse and to determine the incidence of morphologic changes and its risk factors. It was concluded that the used 3-point CMS served its purpose well. In eight patients (4%) resorption of the condyle developed postoperatively. The value of preoperative cephalograms to predict condylar alterations appeared to be limited (12% explained variance). Patients treated at a relative low age (< or = 14 years) appeared to be at risk for the occurrence of condylar alterations including resorption. A steep mandibular plane angle and the low facial height ratio (post:ant) were also significantly related to the occurrence of condylar alteration, but the multi variance regression showed that these parameters had only limited value. The occurrence of pain and TMJ sounds in the first few months postoperatively are highly suspicious for condylar changes to occur in the next months.

Stabilisation of sagittal split advancement osteotomies with miniplates: a prospective, multicentre study with two-year follow-up. Part I. Clinical parameters

The principal aim of this study was to assess the postoperative stability of bilateral sagittal split osteotomies (BSSO) using two miniplates. Part I reports on the clinical results including treatment characteristics, nerve functions, TMJ function, occlusional relapse and patient satisfaction. This prospective study evaluated a group of 222 patients who underwent a BSSO for mandibular advancement. The same treatment protocol was used at seven participating institutions at which the patients were treated. A stable occlusion without appreciable relapse was seen in 84% after 2 years of follow-up. A considerable minority (16%) had occlusal relapse. There were no clinical parameters that pointed towards a high risk for relapse except age. The mean operation age of the relapse group was 20.7 years (SD 6.7) and in the stable group 26.1 years (SD 8.2). The function of the inferior alveolar nerve 2 years postoperatively was reported to be normal in approximately 88% of the patients, while 94% had no complaints about nerve dysaesthesia. In approximately 56% of the patients with pre-existing TMJ-dysfunction these signs and symptoms had disappeared. Another group of patients, however, without TMJ-dysfunction preoperatively (22%) developed signs or symptoms of TMJ-dysfunction postoperatively. The sagittal split osteotomy fixed with miniplates appeared to be a relatively safe and reliable procedure giving rise to a high degree of patient satisfaction, despite the fact that some occlusal relapse was seen.