Tooth Ankylosis Research Articles

Management of Ankylosed Teeth with Fixed Space Regainer: Case Reports

Ankylosis, the abnormal fusion of root cementum and surrounding bone, commonly affects primary molars, leading to space loss and infraocclusion. This often results in mesial tipping of the adjacent permanent molar, necessitating orthodontic intervention to regain space, upright the molar, and establish proper occlusion. In mixed dentitions, patient compliance and proper appliance design are critical, as inappropriate appliances can cause root resorption and undesirable tooth movements. This case report presents a three-step treatment approach for managing ankylosis using a novel fixed appliance that uses the ankylosed tooth as skeletal anchorage. The process includes 1) space regaining, 2) extraction of the ankylosed tooth, and 3) space maintenance for the successor tooth’s eruption. The fixed appliance, comprising a minitube, double-helical spring, free arm, and resin ball, was used to regain space and facilitate the eruption of the permanent successor by correcting the inclination of the adjacent first permanent molar. Two patients with mixed dentitions were treated successfully, achieving space regaining and molar uprighting without anchorage loss. This three-step treatment is simple, effective, and produces desirable outcomes in a short time, making it a promising alternative for pediatric patients with ankylosis, space loss, and mesial inclination of adjacent teeth. The novel appliance emphasizes the importance of stable and biocompatible anchorage in pediatric dentistry.

Replantation After Dental Avulsion: A Scoping Review and Proposal of a Flow Chart.

Dental avulsion, the complete displacement of a tooth from its socket, is a severe dental trauma with a prevalence of 0.5% to 16% of all dental injuries. Replantation of avulsed teeth is common, yet recent studies show high failure rates and unpredictable long-term outcomes. This review examines clinical variables influencing intentional dental replantation decisions and proposes a treatment flow chart. A comprehensive literature search was conducted in PubMed-Medline, Scopus, WoS, and Cochrane databases using the keywords "tooth avulsion," "tooth replantation," and "tooth ankylosis." Inclusion criteria encompassed studies from January 2018 to February 2024. From 752 identified articles, 9 systematic reviews including 3 meta-analyses were selected for this scoping review. Immediate replantation is the gold standard for avulsed teeth, yet delayed replantation is more common in practice, impacting survival rates. Adherence to guidelines from the International Association on Dental Traumatology improves outcomes, especially in paediatric patients. Factors such as multiple caries, severe periodontal disease, advanced age, psychological conditions, immunodeficiency, and lack of cooperation are contraindications for replantation. Despite the high failure rate, replantation remains recommended in literature due to its potential advantages over prosthetic implants. This review highlights the complexities in decision-making for dental replantation, emphasising the need for a comprehensive approach considering individual clinical cases. A proposed treatment flow chart aims to support clinicians in predicting prognosis and making informed decisions. The review also underscores the link between dental trauma, poor oral health, and potential neglect in children, highlighting the importance of preventive measures and parental awareness.

FGF signaling modulates mechanotransduction/WNT signaling in progenitors during tooth root development

Stem/progenitor cells differentiate into different cell lineages during organ development and morphogenesis. Signaling pathway networks and mechanotransduction are important factors to guide the lineage commitment of stem/progenitor cells during craniofacial tissue morphogenesis. Here, we used tooth root development as a model to explore the roles of FGF signaling and mechanotransduction as well as their interaction in regulating the progenitor cell fate decision. We show that Fgfr1 is expressed in the mesenchymal progenitor cells and their progeny during tooth root development. Loss of Fgfr1 in Gli1+ progenitors leads to hyperproliferation and differentiation, which causes narrowed periodontal ligament (PDL) space with abnormal cementum/bone formation leading to ankylosis. We further show that aberrant activation of WNT signaling and mechanosensitive channel Piezo2 occurs after loss of FGF signaling in Gli1-CreER;Fgfr1fl/fl mice. Overexpression of Piezo2 leads to increased osteoblastic differentiation and decreased Piezo2 leads to downregulation of WNT signaling. Mechanistically, an FGF/PIEZO2/WNT signaling cascade plays a crucial role in modulating the fate of progenitors during root morphogenesis. Downregulation of WNT signaling rescues tooth ankylosis in Fgfr1 mutant mice. Collectively, our findings uncover the mechanism by which FGF signaling regulates the fate decisions of stem/progenitor cells, and the interactions among signaling pathways and mechanotransduction during tooth root development, providing insights for future tooth root regeneration.

The Influence of a Single Infrapositioned Anterior Ankylosed Tooth or Implant-Supported Restoration on Smile Attractiveness.

To investigate the influence of a single infrapositioned ankylosed tooth or implant-supported restoration on smile esthetics. A series of 48 digitally modified images that simulated varying degrees of infraposition (from 0.25 to 2.0 mm, with a step of 0.25 mm) were created for each maxillary anterior tooth by altering the full-portrait image of a smiling man, adjusted to show medium and high smile lines. For the model with the high smile line, a series of 24 digitally modified images were created that simulated the infraposition of a single anterior tooth with a restored incisal edge. Smile esthetics for each of the images were evaluated by 160 participants (80 dentists and 80 laypersons), and a visual analog scale (VAS) was implemented. For the images with the high smile line, an infraposition of ≥ 0.25 mm in the central incisor region and ≥ 0.5 mm in the region of the lateral incisor or the canine had a negative effect on the perceived smile esthetics for both the dentists and the laypersons. Regarding the medium smile line, an infraposition of ≥ 0.5 mm in the central and lateral incisor region had a negative effect on the perceived smile esthetics for both groups of observers. In the canine area, an infraposition of ≥ 0.5 mm for the dentists and ≥ 0.75 mm for the laypersons also had a negative impact on the smile esthetics. Even a minor infraposition of a single maxillary anterior ankylosed tooth or implant-supported restoration can reduce the perceived attractiveness of the smile. Infraposition in the canine site can be better tolerated in a medium smile line compared to a high smile line. In patients with a high smile line, prosthetic intervention is needed to restore the incisal edge of an infrapositioned tooth without harmonizing the gingival contour; this can be beneficial for the lateral incisor but ineffective for the central incisor and unfavorable for the canine.

Orthodontic Treatment of an Ankylosed Maxillary Incisor Using a Combination of Surgical Luxation and Temporary Anchorage Device: A Case Report

When anterior tooth ankylosis happens before growth is completed, it leads to dentoalveolar vertical discrepancy which causes anterior openbite and aesthetic concerns. This case report presents a minimally aggressive approach for treatment of an ankylosed tooth in an adult patient using surgical luxation along with temporary anchorage device and vertical elastics. At the end of treatment, the anterior openbite was corrected with extrusion of the ankylosed incisor. The smile arc was significantly improved and the patient was satisfied with the results.

OR070 - TOOTH ANKYLOSIS

OR070 - TOOTH ANKYLOSIS

Osteoproductivity in Experimentally Induced Cranial Bone Defects in Rabbits.

Autogenous bone grafts are the gold standard for being used as graft materials in maxillofacial surgery. However, a limited amount of these materials is available from the donor site, and there is also more need for a larger operating area and a second surgery, which frequently leads to unreliable graft incorporation, tooth ankylosis, and root resorption. Therefore, newer bone graft substitutes have been developed as alternatives, among which eggshell powder has been introduced as a bone substitute. This study aimed to evaluate the biocompatibility, resorption kinetics, and osteoproductivity of the unprocessed, CMC-coated, and gelatin-coated ostrich eggshell particles. Four half-thickness calvarial defects were created in each animal. At the end of the 1st and 3rd months, the defected sites were investigated by clinical, histological, radiological and histomorphometrical methods. Coating the eggshell particles with CMC and gelatin facilitated their surgical application and contributed to new bone formation. However, their newly formed bone rate at the 3rd month was lower than those of the unprocessed eggshell particles. The CMC coating was more effective than gelatin coating in the bone modeling process. Ostrich eggshell particles either in native form or coated with CMC could be used as a bone filler for supporting new bone formation and healing in treatment of osseous defects.

Idiopathic External Cervical Resorption of the Impacted Second Premolar: A Case Report

The tooth impaction of the lower second premolars is an occasional condition but is still seen in clinical practice with a prevalence of 0.6–2.6%. The present case report describes a rare condition of the lower second premolar impaction. An 11-year-old female patient presented with the anteroposterior dental discrepancy, midline shift, and occlusal cant. Intraoral examination revealed the absence of the lower right second premolar with no space available for the eruption. X-ray examination revealed the impaction of tooth #45 in a vertical position, tilting of the adjacent teeth, and two-thirds root length development. The orthodontic treatment plan included space opening using a fixed appliance with a coil spring. The natural eruption of the tooth was expected according to dental age and root development. When the space was opened, no change in the position of tooth #45 was observed. Surgical exposure and active traction were performed. However, the intrusion and tilting of adjacent teeth were observed during the next appointments with no vertical change of tooth #45. Ankylosis was suspected as no tooth movement was recorded. The surgical luxation and osteotomy of the coronal alveolar bone of the impacted tooth were planned for the imminent forced eruption, which was expected due to the young age of the patient. Consequently, the crown of tooth #45 emerged and the bracket was placed. Further traction was planned to use a micro-screw. Following the traction, no vertical displacement of the tooth was observed in the subsequent appointments. Radiographic examination revealed radiolucency in the coronal third of the root. The patient was referred to the endodontist, and CBCT revealed external cervical root resorption in the late reparative stage. ECR in an impacted tooth, mimicking the manifestation of tooth ankylosis, can cause orthodontic treatment failure.

Contouring Crown Aesthetics of a Traumatized Ankylosed Tooth Using Preformed Transparent Polypropylene Thermoplastic Template

Tooth ankylosis is a disastrous sequela of dental trauma that often leads to unaesthetic tooth appearance, especially in the anterior region. The altered dental aesthetic can significantly impact young adolescents’ quality of life and general well-being. This case describes a clinical method to address the aesthetic concern of a 14-year-old young adolescent with a displaced traumatized ankylosed tooth using a preformed transparent polypropylene thermoplastic template. This template allowed recontouring of the tooth in terms of shape and alignment. This method provides an inexpensive option to correct the contour and alignment of a tooth with minimal material wastage, shortening the clinical working time and pleasing aesthetic outcome. As clinicians, one should explore all options and possibilities to work out a solution for a problem. The preformed transparent polypropylene thermoplastic template is one such option that can be used to address dental aesthetics.

Idiopatická (raná) a sekundární (pozdní) ankylóza zubu v klinické praxi a experimentu

Permanent tooth ankylosis is a multifactorial condition. Its origin on the molecular level is still rather unclear, and due to difficult diagnosis, the prevalence in the population is not known. Ankylosis may be classified into idiopathic (early), where the cause is not definitely known, and secondary (late) resulting either from trauma or inflammation around the tooth root. In general, the diagnosis is based on the patient’s history and clinical picture characterized by the loss of the ankylosed tooth mobility accompanied by a distinct sound on percussion. Radiologically, computed tomography (CT) can be used; it is, however, often substituted by Cone Beam Computed Tomography (CBCT) in order to avoid high radiation load. Extraction of the ankylosed tooth is the most common solution. Other methods include tooth subluxation (potentially with corticotomy) or alveolar distraction with orthodontic treatment. Though more and more advanced imaging methods are used, the early detection of tooth ankylosis is still a challenge and must be considered by dentists and orthodontists when planning therapy.

Feasibility of laser-induced breakdown spectroscopy to elucidate elemental changes in human tooth ankylosis

Tooth ankylosis is a pathological condition associated with the loss of physiological tooth mobility when the firm fusion between the alveolar bone and the tooth root occurs. Causes of dental ankylosis are uncertain, so the analysis of elemental distribution in ankylotic and surrounding tissues could provide additional information about its initiation and progression. Here, we used Laser-Induced Breakdown Spectroscopy (LIBS) to determine differences in the mineral composition among ankylotic tissue, bone, and dental tissue taking advantage of its high throughput and multi-elemental capability. Elemental imaging was performed with a spatial resolution of 30 μm to evaluate the distribution of carbon, calcium, magnesium, phosphorus, and strontium in human tooth. To further verify the difference in the mineral composition of ankylotic tissue, the semi-quantitative content of these elements was compared within the region of interest. We revealed a significant increase in calcium, magnesium, and phosphorus contents in the ankylotic tissues. However, the contents of magnesium and phosphorus were not significantly changed. This finding suggests a mineral disbalance only of just certain elements in the tooth-bone interface area during the spread of ankylosis associated with an intense calcification of connective tissue. This paper brings a feasibility study and shows the way of LIBS data interpretation. We propose that the LIBS analysis on a micro-scale can contribute to the understanding of ankylotic tissue composition and can distinguish even small differences of carbon, calcium, magnesium, phosphorus, and strontium contents on the tooth-bone boundary during the initiation of ankylosis. Therefore, it represents a new useful tool for their future, more extensive analyses.

Camouflage Correction of Skeletal Class III Severe Open Bite with Tooth Ankylosis Treated by Temporary Anchorage Devices: A Case Report

Tooth ankylosis is a disorder characterized by the fusion of tooth and alveolar bone. This case report describes the treatment of a severe open bite due to tooth ankylosis. A 14-year-old female patient with a chief complaint of masticatory dysfunction was diagnosed with skeletal Class III severe anterior open bite and tooth ankylosis. She visited our university hospital with a chief complaint of an anterior open bite. After the surgical luxation of the ankylosed maxillary right central incisor, the tooth was orthodontically retracted using a nickel-titanium wire. The right mandibular lateral incisor and canine were luxated and retracted using intermaxillary elastics from a temporary anchorage device (TAD), which was inserted in the opposite jaw. During the treatment, skeletal Class III malocclusion deteriorated due to anterior growth of the mandible. Therefore, TADs were inserted into the retromolar pad on both sides of the mandible and retracted into the mandibular dental arch. Although the mandibular right canine was luxated several times, it could not be brought to the occlusal line, and was thus extracted; the extraction space was replaced with a prosthesis. Consequently, a normal overjet and overbite with a straight profile were achieved. Extrusion of ankylosed teeth by intermaxillary elastics from a TAD is a valid treatment option for patients with severe open bites.

A novel method of objectively detecting tooth ankylosis using cone-beam computed tomography: A laboratory study.

The aim of this study was to objectively detect simulated tooth ankylosis using a novel method involving cone-beam computed tomography (CBCT). Tooth ankylosis was simulated in single-rooted human permanent teeth, and CBCT scans were acquired at different current levels (5, 6.3, and 8 mA) and voxel sizes (0.08, 0.125, and 0.2). In axial reconstructions, a line of interest was perpendicularly placed over the periodontal ligament space of 21 ankylosed and 21 non-ankylosed regions, and the CBCT grey values of all voxels along the line of interest were plotted against their corresponding X-coordinates through a line graph to generate a profile. The image contrast was increased by 30% and 60% and the profile assessment was repeated. The internal area of the resulting parabolas was obtained from all images and compared between ankylosed and non-ankylosed regions under different contrast enhancement conditions, voxel sizes, and mA levels using multi-way analysis of variance with the Tukey post hoc test (α=0.05). The internal area of the parabolas of all non-ankylosed regions was significantly higher than that of the ankylosed regions (P<0.05). Contrast enhancement led to a significantly greater internal area of the parabolas of non-ankylosed regions (P<0.05). Overall, voxel size and mA did not significantly influence the internal area of the parabolas (P>0.05). The proposed novel method revealed a relevant degree of applicability in the detection of simulated tooth ankylosis; increased image contrast led to greater detectability.

Is the efficacy of cone beam computed tomography in the diagnosis of tooth ankylosis influenced by dose reduction protocols?

To evaluate the diagnostic efficacy of cone beam computed tomography (CBCT) examinations acquired with varying dose protocols in the diagnosis of simulated tooth ankylosis (TA). Tooth ankylosis was simulated in 15 of 30 teeth, and CBCT examinations were acquired at 3 mA levels (8, 6.3, and 5) and 3 voxel sizes (0.08, 0.125, and 0.2 mm). Four radiologists independently assessed the presence of TA using a 5-point scale. Sensitivity, specificity, and area under the curve (AUC) obtained through receiver operating characteristic analysis were compared among mA levels and voxel sizes using two-way analysis of variance (α=0.05). Intra- and interexaminer reliability levels were assessed with the weighted kappa examination. Sensitivity was low (0.32-0.49), and specificity was reasonably high (0.71-0.83). Mean values of AUC were low, ranging between 0.54 and 0.67, which reveals poor overall discrimination between health and disease. The detection of TA was not significantly influenced by mA level or voxel size (P > .05). Intra- and interexaminer agreements ranged from slight to moderate (0.160-0.535) and from fair to substantial (0.236-0.697), respectively. Despite the limited efficacy of CBCT for TA detection, when indicated as a complementary examination, mA reduction should be considered for dose optimization purposes.

Traumatized teeth: clinical practice guideline for the interim management of teeth with various poor prognosis scenarios in growing patients.

Many treatment options accepted for unsalvageable traumatized teeth in adults would seem contraindicated in children and adolescents. Instead, growing patients need interim restorative measures, thus extensively preserving their local bone and soft tissue structures and, ideally, preparing the involved site for later definitive restoration while they transform to skeletal maturity. This narrative topic review addresses the interim management in case of very deep intra-extra-alveolar fractures, extensive infection-related root resorption, tooth ankylosis, and anterior tooth loss in growing patients, and seeks to empower the clinician to select the appropriate treatment approach. The literature up to 2021 was reviewed based on several scoping searches on PubMed and the Cochrane Library using relevant terms. Due to the complexity of the topic (with various poor prognosis scenarios and the differing therapeutic options), a systematic review was deemed inappropriate. Suitable interim treatment options include extrusion of teeth showing deep intra-extra-alveolar fractures, and decoronation of ankylosed teeth as well as resin-bonded fixed dental prostheses, natural tooth pontics, and primary tooth autotransplantations after tooth loss. The interim management options described in this article represent compromises chosen in the absence of better alternatives after a careful risk-benefit analysis. However, if adequately performed, the presented treatment options have the potential to achieve the temporary restoration of function and esthetics in growing patients. Close clinical and (if appropriate) radiologic monitoring of these patients is considered mandatory to ensure early detection of possible complications that might jeopardize or could render impossible subsequent therapeutic measures. (Quintessence Int 2022;53:722-731; doi: 10.3290/j.qi.b3236409; Modified from a previously published article (in German) Quintessenz 2022;73(2):162-169).

Primary failure of eruption (PFE) - a systematic literature review

Introduction and purpose&#x0D; Primary Failure of Eruption (PFE) is a rare disease that occurs more often in women than in men. PFE is extremely important for orthodontists because conventional treatment of patients results in ankylosis of the teeth affected by the disease. The aim of the study is to discuss the epidemiology, etiology, diagnosis and treatment of Primary Failure of Eruption.&#x0D; Description of the state of knowledge&#x0D; PFE is present in 0.05% to 0.6% of the population. The average incidence is at the age of 13.65, more often in women. Most often it affects the lateral teeth, and therefore it results in open lateral bites because the teeth do not reach the occlusal plane. The condition was found to be of genetic origin and inherited autosomal dominantly with a low percentage of incomplete penetration. The gene responsible for the disease is the PTH1R. The diagnosis of the disease consists in excluding other causes of eruption failure, detecting disease in which such symptoms occur, and genetic tests (NGS). Treatment of an open lateral bite cannot be carried out in a conventional manner due to the deterioration of the condition after the application of orthodontic forces. The result of the above actions is ankylosis of teeth covered by PFE. The currently proposed methods of treatment are: single or multi-site osteotomy, selective extractions with subsequent implantations, direct or indirect composite restorations, distraction osteogenesis, removable prosthetic restorations.&#x0D; Summary&#x0D; Properly conducted clinical examination of the patient should take into account PFE. Genetic testing (PTH1R) is important in the diagnosis of people with eruption disorders, which is crucial for achieving partially positive treatment results. Orthodontic treatment is contraindicated and patients with a PTH1R mutation should be monitored long-term until their growth is complete, which is the time when interdisciplinary treatment is initiated.

Frequency and Local Etiological Factors of Impaction of Permanent Teeth among 1400 Patients in a Greek Population.

Background: The purpose of this study is to analyze the frequency of impaction of permanent teeth, beyond the third molars, and to highlight the factors causing this condition. Methods: Panoramic radiographs of 1400 patients that sought orthodontic treatment in private practice were retrieved and examined. All teeth that had not been erupted at the time of the examination while their root formation was completed were considered impacted. Results: In total, 212 out of 1400 patients had at least one impacted tooth (15.14%). The highest incidence of tooth impaction was in the canines of the maxilla, followed by the central incisors of the maxilla, the second molars of the mandible and the second premolars of the mandible. The most common etiological factors responsible for the impaction were the ectopic eruption pathway, loss of space in the arch, the ankylosis of the deciduous teeth and the presence of supernumerary teeth. Conclusions: Tooth impaction is frequently seen in everyday orthodontic practice. The upper canines are the teeth most frequently associated with impaction and failure of eruption. It is important to diagnose cases of impaction early on and identify the etiological factors in order to achieve immediate and effective treatment per patient.

Tooth transplantation and replantation: Biological insights towards therapeutic improvements

Transplantation and replantation of teeth are effective therapeutic approaches for tooth repositioning and avulsion, respectively. Transplantation involves transplanting an extracted tooth from the original site into another site, regenerating tissue including the periodontal ligament (PDL) and alveolar bone, around the transplanted tooth. Replantation places the avulsed tooth back to its original site, regenerating functional periodontal tissue. In clinical settings, transplantation and replantation result in favorable outcomes with regenerated PDL tissue in many cases. However, they often result in poor outcomes with two major complications: tooth ankylosis and root resorption. In tooth ankylosis, the root surface and alveolar bone are fused, reducing the PDL tissue between them. The root is subjected to remodeling processes and is partially replaced by bone. In severe cases, the resorbed root is completely replaced by bone tissue, which is called as "replacement resorption." Resorption is sometimes accompanied by infection-mediated inflammation. The molecular mechanisms of ankylosis and root resorption remain unclear, although some signaling mechanisms have been proposed. In this mini-review, we summarized the biological basis of repair mechanisms of tissues in transplantation and replantation and the pathogenesis of their healing failure. We also discussed possible therapeutic interventions to improve treatment success rates.

Platelet-derived growth factor-BB regenerates functional periodontal ligament in the tooth replantation

Tooth ankylosis is a pathological condition of periodontal ligament (PDL) restoration after tooth replantation. Platelet-derived growth factor-BB (PDGF-BB) has been proposed as a promising factor for preventing tooth ankylosis. Using rat tooth replantation model, we investigated whether PDGF-BB accelerates the repair of PDL after tooth replantation without ankylosis, and its molecular mechanisms. In PDGF-BB pretreated replanted teeth (PDGF-BB group), ankylosis was markedly reduced and functionally organized PDL collagen fibers were restored; the mechanical strength of the healing PDL was restored to an average of 76% of that in non-replanted normal teeth at 21 days. The numbers of PDGF-Rβ- and BrdU-positive cells in the periodontal tissues of the PDGF-BB group were greater than those of atelocollagen pretreated replanted teeth (AC group). Moreover, in the PDGF-BB group, the periodontal tissues had fewer osteocalcin-positive cells and decreased number of nuclear β-catenin-positive cells compared to those in the AC group. In vitro analyses showed that PDGF-BB increased the proliferation and migration of human periodontal fibroblasts. PDGF-BB downregulated mRNA expressions of RUNX2 and ALP, and inhibited upregulatory effects of Wnt3a on β-catenin, AXIN2, RUNX2, COL1A1, and ALP mRNA expressions. These findings indicate that in tooth replantation, topical PDGF-BB treatment enhances cell proliferation and migration, and inhibits canonical Wnt signaling activation in bone-tooth ankylosis, leading to occlusal loading of the PDL tissues and subsequent functional restoration of the healing PDL. This suggests a possible clinical application of PDGF-BB to reduce ankylosis after tooth replantation and promote proper regeneration of PDL.

Decoronation - a treatment option of an ankylosed permanent tooth in children and adolescents

Introduction. In children and growing adolescents, ankylotic resorption (i.e., progressive replacement resorption) of a permanent tooth is a serious complication. An ankylosed tooth root is continuously resorbed and replaced with bone; normal growth of alveolar bone is disturbed and infraposition of the dental crown progresses. This article aims to present decoronation as a very good treatment option for permanent incisors diagnosed with progressive replacement resorption in children and adolescents. Case outline. A 9.5-year-old boy was referred with non-vital both upper central permanent incisors due to dental trauma. In the left one, which had been re-implanted 90 minutes after avulsion, progression of clinical and radiographic pathological signs of ankylotic resorption was observed over the months. To prevent the local arrest of alveolar ridge growth and tilting of adjacent teeth, we decoronated the ankylosed tooth. For aesthetic and functional rehabilitation adhesive bonding of his dental crown was performed. Conclusion. In growing individuals with progressive replacement resorption, a dentist should be aware of decoronation as an effective treatment option with a predictable outcome.